FR2859522A1 - Room ventilating method for e.g. school, involves fixing air jet on ceiling surface by Coanda effect, sucking air by aspiration layer fixed to ground surface, and setting average blowing speed lower than average aspiration speed - Google Patents

Abstract

The method involves blowing a previously processed primary air jet (19) into a room. The jet is attached on a surface of ceiling (20) by Coanda effect, according to blowing incidence direction. A foul aspirated air flow (21) is sucked at the level of ground by an aspiration layer attached to a surface of the ground by the effect. Average blowing speed is set to be lower than average aspiration speed. An independent claim is also included for an air-borne decontamination device of a room.

Description

Technical field of the invention

  The present invention relates to methods and devices for ventilating and airborne decontamination to reduce the proportion of airborne contaminating particles of a workpiece, of the operating type: by blending, double-acting Coanda, primary blowing jet attached to the ceiling, and suction flow attached to the floor.

  PRIOR ART Traditionally, air conditioning processes are technically classified according to the way air is distributed in the treated room. Room air conditioning methods can be classified into: unidirectional flow piston air displacement, thermal stratification air displacement ventilation, zone ventilation, mix ventilation, ventilation by localized jet.

  In the vocabulary of ventilation, it is called primary air jet, air previously conditioned (refreshed, reheated, decontaminated, humidified, dehumidified, ....) introduced into a room by a blowing mouth, such as a grid, a perforated panel, a ceiling diffuser ... Called total air, the mixture between the primary air introduced into the room and the air of the room gradually driven by the primary air and mixed with it. In the piston air displacement ventilation strategy, also called unidirectional flow, or laminar flow rooms, the air movement is provided by a unidirectional primary air jet occupying a whole section of the room. The entire surface of a wall of the room, such as the ceiling or sometimes a side wall, is used as the blowing surface of the primary air flow in the room. The air is blown at a speed sufficient to traverse the parallel vein piece towards the opposite wall (usually the floor) which is porous to serve as a suction surface. It is also common to perform air intake by suction wall grids located near the floor, at the bottom of the walls. Laminar flows operate on the piston principle. The primary airflow pushes, like a syringe, the contaminated air that is removed from the room. Laminar flow rooms are used to achieve very low concentrations of contaminants. The exhaust air is taken up in an air handling unit, connected to the building, decontaminated by filtration, mixed with fresh air. Then it is re-bled into the chamber of the room by the blowing surface (usually the ceiling), equipped with high efficiency filters HEPA. The speed of the flow is substantially uniform over an entire section of the workpiece, and reaches between 0.3 m / s and 0.5 m on the entire part to be protected. The blowing and suction surfaces are located: - on opposite walls (perforated ceiling and floor), - on perpendicular walls (ceiling and lower lateral grids), but never on the same wall.

  The flow of air blown by a laminar flow is 10 to 100 times that of a turbulent flow mixing device or a device by displacement of air by stratification with thermal effect. In addition, the entire ceiling must be equipped with a HEPA filter wall. Piston air displacement devices (laminar flow) have: an investment cost of an order of magnitude greater, and an energy cost approximately ten times greater than that of mixing ventilation devices (rooms turbulent flow) or air displacement devices by thermal stratification.

  In addition, their integral wall structure blower (ceiling or wall) makes it impossible to achieve in the form of a mobile system. Piston air displacement devices are used exclusively in decontamination and ultra clean applications and not for air conditioning purposes for which their cost is too high.

  In the thermal stratification air displacement ventilation strategy, one or more low temperature (fresh air) air diffusers are provided on or near the ground. This method works by difference in density of the air inside the room. The level of the new fresh primary air introduced from below, but denser than the ambient air, gradually pushes the ambient air (warmer that floats on the fresh air) upwards. The strategy by stratification is less expensive than that by piston. Its purpose is mainly to ensure a thermal comfort of the occupants of the room. But it is very sensitive to thermal disturbances, and it is not very effective to ensure an aerological decontamination (in particular bacterial or fungal). In addition, the broadcasters it implements are bulky and require significant infrastructure work at ground level. Their realization is impossible in the form of a mobile system. Thermal effect laminating air displacement devices are mainly used in air conditioning applications.

  In the zone ventilation strategy, the principle is to treat certain areas or volumes of the room, while the rest of the room is left without special attention.

  It is generally accepted that the efficiency of zone ventilation is better than that of mixing in ventilated areas. On the other hand, the low overall dilution of the contaminants generally leads to an inefficient global decontamination of the part. In the mixing ventilation strategy, the movement of the air is ensured mainly by the energy supplied by a (or) primary air jet (s) introduced into the room. The theoretical goal of the mixing strategy is to establish uniform conditions for the air inside the room. To do this, the (or) jet (s) of primary air that is (are) injected (s) into the room mix (s) with a large volume of ambient air. This phenomenon is called induction. Mixing ventilation is generally preferable to ensure the best thermal comfort of the occupants. Occupancy zone is the part of the room where occupants are usually located. It is normally defined as the space bounded by a surface 50 cm away from walls with windows, 20 cm away from other walls, and up to 180 cm from the floor. The mixing ventilation strategy aims to mix (as complete and as homogeneous as possible) the primary air with the room air, so that the impurities and contaminants of the room are not only attenuated by dilution but also traditionally evenly distributed. In the same way, it is sought that the room temperature is as homogeneous as possible to avoid the dis-comfort of the occupants. However, the dimensions of the part, the reasonable size and the number of diffusers, generally require that the injection speed of the primary air jet (s) (fresh air) is generally greater than that acceptable for the comfort of the occupants when the jet reaches them. Mixing ventilation methods can be technically divided into two subtypes: - free primary jet blast ventilation; - coanda-attached primary jet blast ventilation.

  According to the free primary jet blast ventilation methods, the primary air jet is injected into the room (usually vertically) through a diffuser generally located in the central part of a wall of the room (usually the ceiling). The primary air jet crosses substantially perpendicularly the envelope of the zone of occupation. The air movements in the room are almost disordered. The air jet reaches the occupants almost directly before being significantly mixed with the air in the room. This often results in a thermal dis-comfort of the occupants. According to the Coanda effect-blown primary blast ventilation methods, the primary air jet is injected into the room through a diffuser located in a lateral region of a wall of the room (generally in the vicinity of the ceiling), and in a direction substantially parallel and tangential to this wall of the room (usually the ceiling). So that the primary jet deploys outside the area of occupancy, between the envelope of the area of occupancy and the attachment wall of the jet. The primary air jet thus travels a long way and is mixed with a large amount of ambient air before reaching the area of occupancy. This arrangement is deemed to be more thermally comfortable for the occupants.

  It has been known since 1910, following experiments made in aeronautics by the Romanian engineer Coanda, that when an air jet is placed sufficiently close to a surface, such as for example a ceiling, the jet of air tends to stick to the surface and continue its movement in contact with it. This phenomenon is called Coanda effect or surface effect. This is due to the fact that an air jet tends to suck the ambient air at its contact to mix with it (diffusion). But in the vicinity of a surface, no ambient air can be sucked. This results in a depression between the airflow and the surface, which tends to stick the air jet against the surface.

  The invention relates to a coanda type ventilation method with a primary jet attached to the ceiling by the Coanda effect and with air intake via a suction mouth in the form of a suction flow attached to the floor, also via Coanda effect. In this type of ventilation, when the dimensions of the room allow it, the jet of air remains effective and reaches the wall opposite the blast wall, before being diluted. The total airflow continues downward along the opposite wall and back toward the suction port near the ground. This gives a kind of enveloping of the occupation zone by the flow of air flowing between the blowing surface and the suction surface.

  The first experimental data on Coanda effect-based primary jet blast ventilation methods date back to 1939 when Baturin and Hanzhonkov demonstrated the reverse flow phenomenon deviated by the ceiling and the opposite wall towards the area of occupancy. Baturin and Hanzhonkov concluded from their analyzes of the shapes of the aeraulic configurations obtained, that the shape of the air movements depended on the location of the blast grid (surface) and was only slightly influenced by the configuration of the grid (surface ) suction and suction conditions. Later theoretical studies published by Nelson, Stewart, Bromleys and Gunes provide information on the distribution of temperatures and velocities in attached primary jet blast ventilation. Other theoretical studies conducted by Linke show that there is a maximum piece length that can be properly ventilated according to this principle. It demonstrates in particular that for linear primary jets attached to the ceiling, having a Reynolds number between 1825 and 12000, the length of the piece must not exceed 3 times its width, to allow establishment of the enveloping flux.

  When the length of the piece is less than this limit (<about 3 times its width), it leads to an enveloping flow to a zone. We can see the description of this phenomenon with regard to Figure 2 described below. It is said that the room is short.

  Beyond this limit, it is said that the piece is long. Aeraulic partitioning of the room is established. A first loop air movement, similar to that obtained in short pieces, consists of a total air jet that follows the ceiling, and descends vertically through the occupying zone in the central part, before join the suction surface horizontally in the vicinity of the ground. Other closed loops of vortex air develop between the first loop and the other end of the room and penetrate inside the zone of occupation. We can see the description of this phenomenon with regard to Figure 3 described below.

  These scientific, theoretical and experimental studies published show that: - if no particular condition is imposed (see below the conditions recommended by the invention concerning the mean speeds of blowing and average suction speed), then, from A certain horizontal distance from the lateral wall of action (including the blowing and suction surfaces) located at about one height of the room, there appears a parasitic inclined flow of shunt.

  This parasitic inclined shunt airflow tends to rise from the ground and cross the occupation zone in an inclined and upward direction towards the blow-out mouth. We can see the description of this phenomenon with reference to Figures 2 and 3 described below.

  Theoretical studies published on airflow patterns and air velocities in a room using an attached primary jet ventilation method, focus only on the thermal applications of ventilation. They aim to ensure that the speeds and temperatures in the area of occupancy are as pleasant as possible for the occupants. The effect generally sought by the prior art, in implementing the attached primary jet mixing ventilation method, is to lengthen the distance that the primary jet travels in the room before entering the occupation zone. . Those skilled in the art [represented by the community of scientists who have published the scientific publications mentioned above] have so far not been interested in the means to be implemented to optimally implement mixing ventilation methods. with primary jet attached for airborne decontamination, and to reduce the proportion of contaminating particles suspended in a room ventilated in this manner. For a person skilled in the art, who is interested, as we have seen above, essentially in the thermal effects of ventilation and the thermal comfort of the occupants, the parasitic inclined air flow of shunt, which tends to climbing from the floor of a room ventilated by primary jet attached to the ceiling by Coanda effect, has rather favorable effects as part of its logic. In the logic of those skilled in the art, this parasitic shunt inclined air flow promotes mixing and therefore the efficiency of thermal ventilation. It is therefore clear that those skilled in the art did not seek to reduce or eliminate this inclined flow of parasitic shunt air, whose effects are however essentially harmful in terms of airborne decontamination. In the ordinary spirit of those skilled in the art, airborne contamination problems are either acute and solved by the unidirectional flow piston air displacement ventilation strategy, the main defect of which is cost, or unimportant and resolved by conventional free-jet mixing, or primary jet blast ventilation, not concerned with the parasitic shunt-induced airflow (which is then neglected), or very low and, in this case, conventional air purifiers by recycling are implemented, resulting in inefficient decontamination, so that parasitic air flows loaded with contaminant particles from the ground and amplified by the presence of parasitic inclined shunt air flow are negligible.

  The main objective sought by the invention is to allow: to benefit from the intrinsic advantages recognized by the attached primary jet ventilation method and notably from its cost of implementation and implementation which is lower than that of ventilation by displacement of air unidirectional flow piston - and comfort for the occupants, while allowing to implement it for applications of advanced decontamination and ultra-cleanliness.

  To do this, the invention aims to reduce (or eliminate) the effects of upward movement of contaminant particles sedimented to the ground that is usually encountered in rooms ventilated by jet blending attached. The main objective of the invention is therefore to propose means for improving the Coanda ceiling-mounted primary jet ventilation method, aimed at reducing or eliminating the presence of the parasitic shunt-induced air flow which tends to to rise from the ground. A secondary object of the invention is to propose a new mobile air decontamination device architecture independent of the building structure, implementing this attached primary jet ventilation method, without parasitic shunt inclined air flow. .

  Mobile air decontamination devices that are independent of the building structure: either operate on a principle of air dilution similar to that of turbulent flow rooms, or implement, such as purifiers, jet type ventilation. located. The distant technological background of the invention comprises mobile air decontamination devices sucking and rejecting air horizontally at almost the same height. Among this class of devices can be mentioned that described in US Patent 6,425,932 Huehn, Deros and Bourque. It is clear that this type of device can implement a primary jet attached to the ceiling and a suction air flow attached to the ground.

  The distant technological background also includes mobile air decontamination devices sucking the air at the top and blowing the air at the bottom.

  U.S. Patent 5,240,478 Messina discloses a HEPA filter scrubber with upper suction and lower blow.

  U.S. Patent 5,612,001 Matschke discloses an upper and lower blow UV lamp purifier.

  US Patent 5,656,242 Morrow and Mc Lean discloses a UV lamp scrubber and upper suction and lower blow electrostatic filter.

  It is easily understood that these purifiers sucking the air at the top and blowing the air at the bottom do not establish a primary air jet attached to the ceiling and that their blowing from the bottom only increases the establishment of Contaminated air streams from the ground

  In the distant prior art, it is also possible to distinguish mobile air decontamination devices that suck in the air at the bottom and reject it at the top but at too great a distance from the ceiling to attach the primary air jet to the ceiling. by Coanda effect.

  U.S. Patent 4,900,344 to Lansing discloses a filter scrubber provided with a bottom-suction sucking nozzle of lower suction type and upper blow at low height without attachment to the ceiling.

  U.S. Patent 5,997,619 Knuth and Carey discloses a filter scrubber and UV lamps with lower side suction and upper blower at low height, without attachment to the ceiling.

  U.S. Patent 6,001,145 Hammes discloses a filter scrubber provided with a bottom-suction sucking nozzle of the low-rise, top-suction type, without attachment of the primary stream to the ceiling.

  U.S. Patent No. 5,453,049, Tillman and Smith discloses a triangular cross-section purifier with a large lower suction through a HEPA filter and vertical top blow through a small, low height opening without attachment of the primary flow to the ceiling.

  U.S. Patent 4,210,429 Golstein discloses a filter filter and UV lamps with lower side suction and upper side low head blowing, without attaching the primary stream to the ceiling.

  These purifiers are of the type by localized jet. None of these documents relate to a device employing a Coanda effect ceiling-mounted primary air jet or a means of reducing or eliminating parasitic shunt airflow between the floor and the ceiling. .

  Finally, we distinguish the mobile air decontamination devices sucking the air at the bottom and rejecting it at the top near the ceiling, which theoretically can be used to attach the primary air jet to the ceiling effect Coanda.

  US Pat. No. 5,290,330 to Tepper, Suchomski and Mex discloses an independent device for air decontamination of horizontal parallelepipedal shape with lower suction and upper blowing, both horizontal. The decontamination of the air is carried out by cylindrical filter cartridges arranged vertically internally to the device. It is stated in this document that the suction and blowing are separated vertically to ensure air movement from the ceiling to the ground. The document does not describe the installation of an air jet attached to the ceiling by Coanda effect or suction flow attached to the ground by Coanda effect. This document does not describe the existence of a parasitic inclined shunt air flow which tends to rise inclinedly from the ground to the ceiling. This document does not describe any way to avoid this phenomenon. Finally, it will be seen that at the sight of the drawings, the suction and blowing grids are similar and of the same dimensions. So that the blowing speed and the suction speed are substantially equal.

  US Patent 5,225,167 Wetzel discloses an independent air decontamination device of substantially parallelepiped shape, to mount the wall of a room and decontaminating the air using HEPA filters and UV lamps. The air is drawn in the vicinity but away from the ground through a grid. The blowing takes place in the vicinity of the ceiling through a quarter-cylinder HEPA filter. The document does not describe the installation of an air jet attached to the ceiling by Coanda effect or suction flow attached to the ground by Coanda effect. The quarter-cylinder shape of the HEPA filter blowhole tends to tilt the primary blast jet towards the floor and is detrimental to its attachment to the ceiling by Coanda effect. The suction mouth placed voluntarily at a distance from the ground is not intended to facilitate the establishment of a suction flow attached to the ground by Coanda effect. This document does not describe the existence of a parasitic inclined air flow shunt that tends to rise from the ground to the ceiling. This document does not describe any way to avoid this phenomenon. Finally, it will be seen that, in view of the drawings, the suction and blowing grids are of substantially the same size. So that the blowing and suction speeds are substantially equal.

  U.S. Patent 5,616,172 Tuckerman, Russel, Knuth and Carey is the closest prior art to the invention. It discloses an independent mobile air decontamination device of substantially parallelepipedal shape elongate, arranged vertically along a wall of the workpiece. The decontamination of the air is carried out by UV lamps and HEPA filters. The air is sucked from the ground by means of a sucking nozzle of the suction type on the ground, formed between the base of the device and the ground. The blower mouth is placed at the top of the device and blows vertically facing the ceiling. The shape of the device is described as deliberately elongated, to increase the distance between the suction grille and the blower grid to avoid short circuits between the two. It is also described the placement of fins on the blower grid to tilt the primary jet blown in the upper part towards the ceiling so that the primary air jet deploys along the ceiling. We can therefore consider, although it is not clearly expressed, that the primary air jet is glued to the ceiling by Coanda effect. However, this document considers that the only way to avoid the shunt effect between the suction and blowing grids is to separate them as much as possible from each other. This provision is certainly necessary. But as the scientific documents mentioned above show and as will be shown by the demonstrations made later, this is not enough. First of all, this document does not take into account the existence of an inclined parasitic shunt air flow which tends to rise from the ground (in the middle of the room), and to cross the zone of occupation in such a way tilted and upwards towards the blowing mouth. It is only interested in the direct shunt between suction and blowing, which is another problem.

  This document therefore recommends no means relating to: the ratio between the suction speed and the blowing speed, or the ratio between the effective suction area and the effective blowing surface, in order to reduce and / or eliminate the flow of parasitic inclined shunt air that tends to rise from the middle of the ground to the ceiling, despite the gap between the grids.

  The relative dimensions of the suction and blast surfaces are unspecified. Now, without these geometrical precautions and particular flow speeds, the scientific studies mentioned above and the demonstrations made below, show that the spacing of the blowing and suction grids is not sufficient to eliminate this phenomenon of flux of flow. inclined parasitic shunt air.

  Those skilled in the art consider, as we have seen above, that the suction mouths are of minor importance in the movement of the air and that they only influence their close neighborhoods. We will not show further that the man of the art is wrong. The prior art is therefore very little interested in the influence of the shape and location of the suction mouths. It seems that no scientific study has so far been conducted on the subject.

  It therefore appears that, although the method of blowing by mixing with primary blowing jet attached to the ceiling and suction flow attached to the ground by double Coanda effect is known and widely used for its thermal qualities in the field of air conditioning, its use is almost non-existent in the field of airborne decontamination because the effect of inclined parasitic shunt air flow it generates has not been solved by the prior art and this degrades its decontamination performance.

  SUMMARY OF THE INVENTION The invention relates first of all to a method of ventilating a workpiece by mixing a primary blowing jet attached to the ceiling and suction flow attached to the ground, by a double Coanda effect. The invention specifically relates to ventilation methods of the type according to which the room is blown into a pre-treated primary air jet (heated, cooled, decontaminated, moistened, dehumidified, etc.) through a blowing surface. , located opposite a lateral wall said treatment, in the vicinity of the ceiling, and in a direction of blowing incidence [average on the blowing surface of the mean directions of the portions of the primary jet] oriented in the direction of the ceiling (or parallel to this one), so as to attach by Coanda effect said primary jet of blowing on the surface of the ceiling. At the same time, a sucked-up sucked-air flow of flow equivalent to the primary jet is sucked through a substantially vertical suction surface situated opposite the same lateral treatment wall, in the vicinity of the floor of the room. In this way, it ensures at the ground level sucking air along a suction line substantially horizontal, parallel and attached to the ground surface by Coanda effect.

  The empirical experiments carried out to date on the primary blowing air blast ventilation system attached to the ceiling and the suction flow attached to the ground and the computer simulations that have been operated by the inventors show that in a closed room, this type In the case of ventilation, a parasitic shunt air flow occurs which tends to rise from the ground and cross the occupancy zone in an inclined and upward direction towards the air intake. This phenomenon is widely described by the prior art and scientific publications described above, with no solution found to eliminate it.

  In its simplest form, the ventilation method according to the invention consists in that, in addition, the average blowing speed (Vs) [average of the speeds of the portions of the primary air jet on the surface of blowing] to be lower than the average suction speed (Va) [average speed of portions of the air flow sucked on the suction surface] [Vs <Va]. The inventors have found, computer modeled and demonstrated by aerodynamic measurements on independent airborne decontamination devices of a part implementing this method, that this parasitic shunt air flow phenomenon is greatly attenuated or eliminated, when the means of the invention are implemented.

  Brief description of drawings and figures

  Figure 1 shows schematically, in side view, the phenomenon of sedimentation of aerosols and resuspension in an unventilated room. FIG. 2 diagrammatically shows, in lateral view, the distribution of the air flows in a short ventilated room (without particular precautions) by mixing with a primary blowing jet attached to the ceiling and a suction flow attached to the floor (reproduced from FIG. Muller).

  FIG. 3 diagrammatically shows, in lateral view, the distribution of the air flows in a long ventilated room (without any particular precautions) by blowing with a primary blowing jet attached to the ceiling and a suction flow attached to the floor (reproduced from FIG. Muller).

  FIG. 4a schematically represents, in lateral view, the distribution of the air flows obtained by computer simulation of a ventilation device (of the type of FIG. 2) operating in a ventilated room by a primary blowing mixture attached ceiling and suction flow attached to the ground, according to the teachings of the invention.

  FIG. 4b schematically represents, in perspective, the distribution of the air flows obtained by computer simulation of a ventilation device (of the type shown in FIG. 4a) operating in a ventilated room according to the teachings of the invention and showing a a detailed view of the effective side suction and blowing surfaces of the ventilation device of Figure 4a to assess their relative sizes and mean velocities suction and blowing.

  FIG. 5a schematically represents a portion of animated air vein allowing the analytical demonstration of the advantages implemented by the invention and of eliminating the parasitic shunt air flow.

  FIG. 5b diagrammatically represents the numerical simulation conditions of the airflow diagrams obtained for a prototype of the independent airborne decontamination device of the invention.

  FIG. 5c represents a table of values of the results resulting from the calculation in numerical simulation as illustrated in FIG. 5b.

  Figure 5d is a graphical illustration of the results obtained as shown in Figure 5c.

  FIG. 6 schematically represents, in lateral view, the air flows obtained by computer simulation of an independent decontamination device operating in a room according to the teachings of the invention.

  Figures 6a and 6b show in section and in perspective, an enlarged view of the independent decontamination device of the invention.

  FIG. 6c shows a view from above of the operation of the device of FIG. 6 and a view of the air streams that it generates horizontally.

  - Figure 6d schematically shows an enlarged side view of the sucking nozzle of the independent decontamination device of Figure 6 and its action on the contaminating particles in suspension and those located at ground level. Figure 6e shows schematically, in perspective, a view of the device of the invention and its suction vein.

  Figure 7 shows schematically, in side view, the principle of operation and action on aerosols of a decontamination device operating in a room according to the teachings of the invention.

  Figures 8a and 8b show in section and in perspective a view of the blowing nozzle of the independent decontamination device of Figure 6 and its position relative to the ceiling.

  - Figures 8c to 8h show, in side view, the influence of the adjustment of the blast angle of incidence of the device of the invention.

  Figures 9a and 9b show, in side view, the importance of a recommended variant of the invention relating to the adjustment of the suction and blowing speeds.

  Figure 10a shows in perspective, a detail of a first preferred embodiment of the invention for producing the blowing nozzle.

  Figure 10b shows in perspective a detail of a second preferred embodiment of the invention for producing the blowing nozzle.

  Figure 11 shows, in perspective, a detail of a preferred embodiment of the invention for producing the sucking nozzle.

  Figure 12 shows, in perspective, a preferred embodiment of the invention for producing the reduced thickness vertical channel means.

  Figures 13a and 13b show, in perspective, a preferred embodiment of the invention for producing the vertical pipe means adjustable height. Figures 14a and 14b show, in perspective, a preferred embodiment of the invention for producing the device of Figure 6 to auxiliary squelching nozzle. Figures 15a and 15b show, in perspective, a preferred embodiment of the invention for producing the device of Figure 6 expandable blow nozzle.

  Detailed description of the invention Figure 1 describes a room (3) unventilated conventional. The ambient air (A) of the part (3) is filled with a multitude of contaminating particles (4) comparable to aerosols which, under the action of their weight and gravity, are due to sedimentation effect (5). ) driven at ground level (6). So that the contaminating particles (4) will, with a low vertical sedimentation rate (5), gradually accumulate in a thin layer of highly contaminated air (Cc) in contact with the ground (6). If the contaminant particles (4) included in the part (3) are taken into account, a small portion of the contaminating particles (4), although extremely dangerous for the occupants (1), is present in suspension in the form of suspended contaminant aerosols (4a) contained within the volume of the workpiece (3). Another very dense portion of the contaminating particles (4) is, under the effect of gravitation, convective thermal movements from the ground (6) and Brownian motions accumulated in the form of accumulated contaminating aerosols (4b) under form of a kind of cloud, inside the thin layer of highly contaminated lower air (Cc). Within this fine layer of highly contaminated lower air (Cc), the concentration of accumulated contaminant aerosols (4b) is asymptotic as it approaches the ground (6). But most of the contaminating particles (4) present in the part (3) are the adhered particles (4c) which, following their long descent under the effect of gravitation, have adhered to the ground (6) by forces of Van der Waals, arising from interactions between the molecules they contain and the soil (6).

  Area of occupancy (2) is the part of the room (3) where the occupants (1) are usually located. It is normally defined as the space delimited by a surface 50 cm away from the walls (50) including windows (51), and 20 cm away from the other walls (140). It rises up to 180 cm from the ground (6).

  The occupants (1), during their movements in the room (3), will generate disturbances and turbulences (7) at ground level (6) and resuspend, by ascension-type disturbance currents (8) , some of the accumulated contaminant aerosols (4b) and adhered particles (4c) located at ground level (6) in the lower part of the area of occupancy (2). A phenomenon similar to that leading in meteorology to the formation of powerful clouds of cumulonimbus type develops on a reduced scale in the room (3). The light rays (53) of the lighting (54) disposed on the ceiling (20) and coming from the window (51) cause an inhomogeneous reheating of the floor (6). On the ground (6), powerful upward convection motions (57) result in high resuspension of some of the accumulated contaminant aerosols (4b) and adhered particles (4c) located on the ground (6). These contaminant aerosols (4b, 4c) rise up in the upper portions of the occupancy zone (2) and reach the mouth and the respiratory areas (9) of the occupants (1). So that these contaminant aerosols (4b, 4c) resuspended by these phenomena, increase the content of suspended contaminant aerosols (4a). They increase the risk of being sucked by occupants (1) of the room (3) and by the same, the probability of biocontamination of these occupants (1) by airborne biological agents likely to develop different types of diseases (Aspergillosis, pneumonia ...). The prior art makes extensive use of the blowing primary blast ventilation method (19) attached to the ceiling (20) and the suction flow (21) also attached to the floor (6), both by Coanda effect (C). . Figures 2 and 3 show the implementation of this ventilation method according to the prior art using a fixed ventilation device (65) related to the building containing the part (3). According to the prior art, a primary air jet (19) previously treated by the fixed ventilation system (65) (heated, cooled, decontaminated, humidified, dehumidified, etc.) is blown into the room (3). through a wall-blowing mouth (10) formed in the first vertical treatment wall (52) and opening into the room (3) by a blast surface (Ss) located opposite the vertical treatment wall ( 52), in the vicinity of the ceiling (20). The primary air (19) is directed in a direction of blast impingement (Is) [average on the blowing surface (Ss) of the average directions of the portions of the primary blast jet (19)] oriented towards the ceiling ( 20) (or, usually as shown in Figures 2 and 3, parallel thereto), so as to Coanda effect (C) said primary blast jet (19) on the surface of the ceiling (20). At the same time, a sucked-up sucked air flow (21) with a flow rate equivalent to the primary jet (19) is drawn through a suction mouth (11) formed in the vertical treatment wall (52) and opening in the room (3) through a suction surface (Sa) substantially vertical, located opposite the same side treatment wall (52), in the vicinity of the floor (6) of the room (3). This ensures at floor level (6) a sucking air (A) in a flared suction vein (55) substantially horizontal, parallel and attached to the ground surface (6) by Coanda effect (C ). The primary air jet (19) extends out of the occupancy zone (2) between the envelope (63) of the occupancy zone (2) and the jet attachment wall ( 19) constituted by the ceiling (20). The primary air jet (19) travels a long way and is mixed with a large amount of ambient air (A) before reaching the occupancy zone (2). It is this mixture that causes dilution between stale air and fresh air, which leads to air conditioning and decontamination, object of ventilation. This arrangement is deemed to be more thermally comfortable for the occupants (1). The fixed ventilation system (65) includes an external air handling unit (73), generally located on the roof of the building. That shown is a combined blow molding and recovery unit commonly used in the field of recycling air treatment. It comprises one or more fans of the centrifugal or other type (67) and (71) allowing the movement of the air (A) and the installation of the ventilation diagram, a heating battery (70), a filter with air (69) and a mixing box (68) between recirculated air and outside fresh air. The air handling unit (73) is connected to a diffusion duct (72) opening on the wall-blowing mouth (10), and thus delivering the previously treated primary jet (19) through the blowing surface (Ss ). The suction duct (66) connects the wall suction outlet (11) to the inlet of the air handling unit (73) to evacuate the sucked and / or contaminated exhaust air flow (21). the room (3).

  FIG. 2 describes the aeraulic diagram (reproduced from Muller) obtained, according to the prior art, inside a so-called short piece (3a), whose length (L) is less than approximately three times its width (1). This results in a wrapping flow at a loop (B 1). It can be seen that according to the prior art (without any particular precaution), there appears a parasitic shunt air flow (Fs) which rises from the ground (6), and passes through the zone of occupation (2) inclined and upwards towards the blowing surface (Ss). It is understood that the parasitic shunt air flow (Fs) that rises from the ground (6) causes a resuspension of the accumulated and ground-level contaminants (4b, 4c) (6) with consequences similar to those described in Figure 1. These contaminants (4b, 4c), during their ascent, will increase the content of aerosols suspended contaminants (4a) in the ambient air (A) of the room (3). ). According to the prior art, the risk of aerial biocontamination is therefore increased in short pieces (3a) ventilated by an attached jet mixture (19), because of the existence of this parasitic inclined shunt air flow ( fs). FIG. 3 describes the aerodynamic diagram (adapted from Muller) obtained according to the prior art within a so-called long part (3b) whose length (L) is greater than approximately 3 times its width (1) . It is noted that aeraulic partitioning of the long piece (3b) is established in several air zones (Z1, Z2, Z3, ...). A first closed air loop (B 1), similar to that obtained in the short parts and visualized in FIG. 2, is established in the first zone (Z1). It consists of a primary blast air jet (19) which follows the ceiling (20), and descends vertically along an inclined branch (77) through the substantially central portion of the occupying zone (2). the long piece (3b), before reaching horizontally near the ground (6) the suction surface (Sa). In addition to the fact that the parasitic shunt air flow effect (Fs) which rises from the ground (6) is also present, other closed air loops (B2, B3,. vortex (12a, 12b) develop between the first loop (B1) and the wall (50) located at the other end of the workpiece (3) in the successive zones (Z2, Z3). These closed loops of air (B2, B3, ...) penetrate inside the zone of occupation (2). This second phenomenon is due to the fact that due to the long length (L) of the part (3), the primary blast jet (19) comes off early in a separation zone (14) of the ceiling (20). The primary blast jet (19) is then no longer attached to the ceiling (20) but qualified free. This also causes a succession of speed induction effects (30a, 30b, ...) and leads to the formation of the secondary vortices (12a, 12b) resulting in the creation of the closed loops of air (B2, B3, ...) in the secondary zones (Z2, Z3, ...). The suspended contaminant aerosols (4a) located in the secondary vortex zones (12a, 12b) of the closed air loops (B2, B3, ...) are trapped and removed from the blow-off surfaces (Ss) and suction (Sa) of the fixed ventilation system (65) and decontamination. The suspended contaminant aerosols (4a) can, however, be transported between the different closed loops of air (B1, B2, B3, ...) via exchange zones (17a, 17b) present in the state steady state of the workpiece (3). The part (3) is therefore not optimally treated throughout its volume since the decontamination treatment is slowed down in the evacuation of the suspended contaminant aerosols (4a). In addition, it is understood that the multiplication of upward movements resulting from air loops (B1, B2, B3, ....) increases the resuspension of the contaminant aerosols (4b, 4c) accumulated and adhered to the ground level ( 6) and therefore the risk of biocontamination of the occupants (1) in the area of occupancy (2). To reduce the risk of biological contamination by air, it is preferable to use the attached jet blowing method in short pieces (3a).

  FIGS. 4a and 4b schematically describe the characteristic means implemented by the method of the invention in a short piece (3a) to considerably reduce or even eliminate the effect of parasitic inclined shunt air flow (Fs) described in FIGS. 2 and 3. The method of the invention implements the general principles described in FIG. 2 of a primary blowing blast ventilation method (19) attached to the ceiling (20) and suction flow (21) attached. on the ground (6) by Coanda effect (C). However, the method of the invention is remarkable in that it imposes on the average blowing speed (Vs) [average speeds of the portions of the primary air jet on the blowing surface (Ss)] to be lower than the average suction speed (Va) [average speed of the portions of the air flow sucked onto the suction surface (Sa)] [Vs <Va].

  A first analytical demonstration of the advantages of this means, certainly simple, implemented by the invention, but leading to the effect [considerable advantages for airborne decontamination (not achieved by the prior art)] to eliminate the flow Shunt parasitic air (Fs) can be made using Bernoulli's theorem next to Figure 5a.

  Figure 5a shows a detail of a moving air vein portion (vf) in permanent motion. It is considered, for the sake of simplification, that air (A) is a perfect incompressible fluid subject to the forces of gravity alone. And we extract from this vein of animated air (vf) an infinitesimal portion of air (da) in motion. -17.-

  The infinitesimal portion of air (da) belonging to the vein (vf) has: a variable section (s), a variable velocity (V), a variable length (dx), a mass (dm), - and a local pressure (P).

  The air has a density (p) considered constant. The acceleration of gravity is constant and equal to (g).

  As a first approximation, the total mechanical energy And of infinitesimal portion of air 10 (da) is the sum of: its kinetic energy Ec = '/ z dm * V2, its potential energy of pressure Epr = P * s * dx = P * dm / p, and its potential gravitational energy Epe = g * z * dm.

  The total mechanical energy and infinitesimal portion of air (da) is first approximated conserved along any animated fluid vein (vf).

  So that per unit mass of air moving along any animated air vein (vf), the expression: V2 / 2 + P / p + g * z = constant. This is an expression of Bernouilli's theorem, valid in the absence of energy expenditure (which we will take into consideration later) along any animated air vein (vf) in a room (3).

  Referring to FIG. 2, we will make a demonstration by the absurd ending in the necessity of the means of the invention, namely that the average blowing speed (Vs) is lower than the average suction speed ( Va)] so that the parasitic shunt air flow effect (Fs) is absent from the part (3) described in FIG. 2.

  Indeed, if there was no parasitic shunt air flow effect (Fs), all the veins from the blowing surface (Ss) would join the suction surface (Sa). If we consider the multitude of animated air veins (vf) that join: the blowing surface (Ss) where the average air blowing speed is (Vs), the blowing pressure is (Ps), and where the height is (h) at the suction surface (Sa) where the average air suction velocity is (Va), the suction pressure is (Pa), and the height (h) is none, they would all be continuous and not broken (in several streams) along their length. We could legitimately apply the Bernouilli theorem in medium form on the blow (Ss) and suction (Sa) surfaces and result in: Vs2 / 2 + Ps / p + g * h = Va2 / 2 + Pa / p (Bernouilli averaged)

  It seems important to highlight that it is the very existence of this non-splitting of the veins (vf) that makes it possible to implement Bernouilli's theorem in average form. Because in this case, it can be considered that any vein (vf) from the blowing surface (Ss) leads to the suction surface (Sa) and vice versa. This would not be the case if there was a parasitic shunt airflow (Fs). However, it is obvious that the fact that the air is blown into the room (3) by the blowing surface (Ss) and sucked by the suction surface (Sa) requires that Ps> Pa.

  Suppose now that Vs> Va. In this case, it appears that the left-hand member of the equality (Bernouilli averenne) considered above is strictly superior to the right-hand member of this same equality. We conclude that the equality imposed by Bernouilli's Theorem would not be verified. This can be expressed by: [Absence of the parasitic shunt (Fs) inclined air flow effect of the workpiece (3)], 10 - And [Vs> Va] => Nonobservance of the Bernouilli theorem averaged over the blow (Ss) and suction (Sa) surfaces.

  The logical mathematical contraposition of the expression above imposes: Respect of the Bernouilli theorem => - [Existence of the effect of inclined parasitic shunt air flow (Fs) in the room (3)], - or [ Vs <Va].

  It has therefore been demonstrated that in a room (3), the means of the invention, namely [Vs <Va], is a necessary condition for the absence of the parasitic inclined airflow effect 20 of shunt (Fs) in the room (3).

  In fact, the imposed condition is more severe. In the permanent flow of the animated air vein (vf), a part of the total mechanical energy is dissipated under the effect of external forces such as: friction at the walls of the room (3) and especially due to the induction effect between the primary air jet (19) and the air (A) of the part (3). Between the two ends of the animated air vein (vf) there is dissipation of a loss of friction load AH. The Bernouilli theorem applied to the animated air vein (vf) and corrected by the influence of the pressure drop then becomes: Vs2 / 2 + Ps / p + g * h = Va2 / 2 + Pa / p + AH (Bernouilli with losses of load).

  It is therefore necessary, in the absence of an inclined parasitic shunt air flow (Fs) in the room (3), that: (Va2 -Vs2) / 2 = (Ps - Pa) / p + g * h - AH Vat = Vs2 + 2 * [(Ps - Pa) / p + g * h - AH] Let Va <(Vs2 + 2 * [(Ps-Pa) / p + g * h]) 1/2 We thus arrive at the following condition: Vs <Va <(Vs2 + 2 * [(PsPa) / p + g * h]) "2 If the average suction speed (Va) is lower than the blowing speed (Vs), it is establishes a parasitic shunt air flow (Fs) and the Bernouilli theorem is no longer applicable in its average form If the average suction velocity (Va) is greater than the blowing velocity (Vs), the parasitic shunt air flow phenomenon (Fs) weakens and then vanishes gradually, and the higher the average suction speed (Va) exceeds the blowing speed (Vs), the more the induction phenomena leading to the mixing of the air with the induced primary jet (19) develop and consume the pressure drop AH. imitate Va> (Vs2 + 2 * [(Ps - Pa) / p + g * h]) 1'2, we can estimate that the Coanda (C) effect flow can not be established and that we are witnessing to a mainly turbulent movement.

  This is of course a demonstration with very simplifying assumptions but which allows to understand the importance of the adjustment of the average suction speed (Va) compared to that of blowing (Vs) and therefore the importance of this mean yet simple [Vs <Va] recommended by the invention.

  Figure 4a shows very schematically the results obtained by the inventors, and from the experimentation and the joint use of computer aeration simulation tools. It describes the aeraulic diagram of the air movements (A) in a room (3) similar to that described in FIG. 2, but in which the means of the invention relating to the ratios between the average blowing speed (Vs) and the average speed of suction (Va) have been implemented. These results, derived from aerodynamic simulation calculations and measurements made on prototype devices using these means, have made it possible to demonstrate that when the means recommended by the invention are implemented in the part (3), that is, that is, when it is imposed that the average blowing speed (Vs) [mean of the speeds of the portions of the primary air jet (19) on the blowing surface (Ss)] is less than the average speed of suction (Va) [average speeds of the portions of the intake airflow (21) on the suction surface (Sa)] [Vs <Va] then strongly attenuates (see is avoided) the flow effect of parasitic shunt air (FS) of the prior art as described with reference to FIG. 2. This parasitic shunt air flow effect (FS) is mainly due to the induction forces generated by the primary jet blowing (19). By favoring the induction forces generated by the suction flow (21), which are directed towards the ground (6), to the detriment of the induction forces generated by the primary blast jet (19), the balance of interactions of these two types of moments makes it possible to keep the air flow sucked (21) glued to the ground (6) by Coanda effect (C). The dilution of the part (3) is closely connected to the air flow used, at the outlet of the blowing surface (Ss) and at the inlet of the suction surface (Sa). It is not a question here of improving the dilution yield (which is approaching 100%), but of improving decontamination in terms of quality. As the parasitic shunt airflow (Fs) is eliminated, the aeraulic lift of the contaminant aerosols (4) in the zone of occupancy (2) does not occur, and therefore the probability of bioburden occupants (1) is reduced, insofar as these biocontaminants (4) remain mainly confined in the thin layer of highly contaminated air (Cc) and are not in contact with the respiratory zones (9) of the occupants (1).

  FIG. 4b shows in perspective the arrangements to be implemented in a part (3) in terms of the effective blow-off area (Sse) and the effective suction area (Sae) for implementing in a fixed ventilation system (65) the means of the invention. The blower (10) and suction (11) wall vents used in the fixed ventilation systems (65) are generally equipped with blower (60) and suction (61) grids which materialize the blowing surfaces (Ss ) and suction (Sa) but partially block the air flow. These grids (60,61) usually consist of a metal plate provided with a multitude of holes, or a metal frame (81) provided with a plurality of directional lamellae (83) and / or any other means partially obstructing the corresponding mouth (10,11), while being porous to the air. The effective area (Sse, Sae) of a grid (60, 61) is the area of the empty virtual grid that would have the same overall mean aeraulic behavior of the torque [velocity of fluid (Vs, Va) passing through it / pressure ( Ps, Pa)]. Grids sold commercially are usually accompanied by specifications indicating their effective surface area. Otherwise it is possible to measure it empirically. In Figure 4b, there is shown the blow grille (Ss) and a representation of its blowing section (Sse). The suction grid (Sa) and a representation of its suction cross section (Sae) are also shown. It is understood that it has been imposed in the part (3) that the effective blowing surface (Sa) is greater than the effective suction surface (Sa). This makes it possible to have [Vs <Va]. It can be seen that the primary blast jet (19) issuing from the blowing surface (Ss) is perfectly bonded to the ceiling (20) by the Coanda effect (C). The suction line (55) of the suction air stream (21) is also perfectly bonded to the ground (6) by the Coanda effect (C). No inclined parasitic shunt (Fs) airflow is present in the room (3).

  FIG. 5b represents the numerical simulation conditions of the airflow diagrams obtained for a prototype of the independent airborne decontamination device PLASMAIRTM (101) operating according to the means of the invention in a room (3), as a function of different effective blowing ratios. (RS). Blowing ratio (RS) is the ratio between the effective blowing surface (Sse) and the effective suction area (Sae). The numerical simulations were carried out under the following conditions: Length of the piece (L) = 4 m Width of the piece (1) = 3m Height of the piece (h) = 2.5 m Air flow: Qv = 500 m3 / hour.

  The axes (X), (Y), (Z) and the list of different points (P = P1, P2, ..., P8) of simulations are arranged at 2 cm from the ground (6) as represented in FIG. 5b. The numerically calculated quantity (Yvelocity) represents the local numerical mean of the vertical component of the air velocity, taken at each of the points (P = P1, P2, ..., P8) distant from (d = dl, d2 , d8) of the end face (165) of the device (101). It is the average of the vertical component of the air velocity, in a cubic volume constituted by the union of 9 elementary cubic simulation meshes arranged contiguous and centered on each simulation point P. The device (101) is placed against and in the central part of the so-called treatment wall (52). The energy model called K-E is used to establish the air movements from the Navier-Stokes equations. Although the regime concerned is turbulent, the studied spatial dimension state of motion is much larger than Kolmogorov scales (molecular type description) of fluid particles so that the Navier-Stokes equations apply. In this numerical simulation, a smoothing of the movements of the air molecules is implemented.

  The reliability of the use of this numerical method does not currently know any known counter-example, for fluid speeds lower than Mach 13. This is of course the case in this study. The type of meshes chosen is hexagonal because of the simple architecture of the piece (3). The number of stitches is 500000 to cover the piece (3). This number is much higher than the theoretical one of 3000, usually considered sufficient for the validation of this type of study. By the definition of Yvelocity (P), it is understood that this parameter, which can be positive or negative, is very significant of the existence of upward or downward movements of the air (A) in the room (3).

  Thus, if Yvelocity (P) is positive, it means that the velocity of the air near the point (P), located two cm above the ground, has an average component inclined upwards. In this case, it is deduced that there are mainly upward currents on the ground near the point (P). It can be concluded that there is a good chance that a parasitic shunt airflow (Fs) starts from this point.

  On the contrary, if Yvelocity (P) is negative, it means that the velocity of the air, in the vicinity of the point (P), has a mean component inclined downwards. It can be concluded that there is little chance that a parasitic shunt airflow (Fs) will start from this point. The table in Figure 5c gives the results obtained by this simulation. In this table, the first column designates the simulation point (P = P1, P2, ..., P8). The second column (grayed) refers to the case where the device (101) has been adjusted so that the blowing ratio (RS = 0.57) [ratio between the Effective Blowing Surface (Sse) and the effective suction area (Sae)] is less than 1. That is to say that one is outside the conditions imposed by the invention. We are in the probable conditions of formation of the parasitic shunt flux (Fs) as predicted by the theoretical analysis developed above.

  The third column (grayed) corresponds to the case where the device (101) has been adjusted so that the blowing ratio (RS) is equal to 1. This is the limit case of presence of the parasitic shunt flow (Fs) such than predicted by the theoretical analysis developed above. The second and third columns are grayed out to better delineate the conditions outside the application of the recommendations of the invention.

  Finally, the fourth column (not greyed) refers to the case where the device (101) has been set so that the blowing ratio (RS = 1.43) is greater than 1. That is, the we are in the context of the conditions imposed by the invention.

  Under the conditions of column 2 where (Va = 0.57 Vs), that is (Va <Vs), it is found that the local digital average of the vertical component of the air velocity is positive. at points (P4) to (P7) remote from the device (101). This means that there is presence of upward movements of the air in the portion of the room (3) furthest from the device (101). It is reasonable to conclude that a parasitic shunt flow (Fs) rises from the extreme part of the part towards the blow-out mouth (110). Under these conditions, the use of the device (101) as airborne decontamination system is very inefficient due to the presence of upward currents at ground level (6).

  In the conditions of column 3 where (Va = Vs), it is also found that the local digital average of the vertical component of the air velocity is positive at the points (P5) to (P7), distant from the device (101). ). This means, as previously, that there is presence of upward movements of the air in the portion of the room (3) most distant from the device (101). It can be concluded that a parasitic shunt flow (Fs) rises from the end of the piece (3) toward the blow-out mouth (110). Under these conditions, the use of the device (101) as an airborne decontamination system is also very inefficient due to the presence of upward currents at ground level (6).

  By cons, under the conditions of column 4 where (Va = 1.43 Vs), that is to say (Va> Vs), it is found on the contrary that the local average of the vertical component of the speed of the air is always negative at all points (P1) to (P8). It can be concluded that no parasitic shunt flow (FS) rises from the room (3). Under these conditions, the use of the device (101) as airborne decontamination system is very inefficient due to the absence of upward currents at ground level (6).

  The capabilities of the method of the invention to eliminate the shunt parasitic inclined air flow phenomenon appear more clearly in the diagram of FIG. 5d. This represents, as a function of each of the 3 blowing ratio conditions (RS) referred to above, the curve of the parameter Yvelocity (P) as a function of the position of the different points (Pl, P2, ..., P8). simulations on the ground (3) in Figure (51)). It is conceivable that, for a given blowing ratio (RS), the existence of a parasitic shunt-induced air flow results in an incursion of the Yvelocity curve into the hatched area (Yvelocity> 0). This numerical demonstration makes it possible to conclude from the effectiveness of the conditions recommended by the invention, namely: - (Va> Vs), - or, what is equivalent, Effective Blowing Surface (Sse) greater than Effective suction area (Sae), to eliminate the parasitic shunt flow (Fs), which was nevertheless considered inevitable by those skilled in the art.

  The principles of the method of the invention, to meet the defects of the prior art, can be advantageously implemented within the independent airborne decontamination device PLASMAIRTM (101). An independent mobile device for airborne decontamination (101) according to the invention is shown in FIG. 6, installed in a short part (3a), to implement the blowing process by mixing with a primary blowing jet (19) and a flow of Aspiration (21) attached to Coanda double effect (C). The device (101) has a vertical channeling means (103) placed vertically. It is intended to be disposed substantially parallel and close to a first vertical treatment wall (52) of the short piece (3a) to be treated. The channeling means (103) has a first lower suction end (104) located in the lower part in the vicinity and at a distance from the ground (6) of the short piece (3a). The channeling means (103) has a second upper blow end (105), located higher. It is intended to be located in the upper part in the vicinity and at a distance from the ceiling (20) of the short piece (3a). The device (101) is equipped with means for moving (106) the air (A). This is disposed within the riser means (103). It creates an overpressure (AP = Ps - Pa) between the upper blowing end (105) and the lower suction end (104), to allow the movement of air (A) to the outside. It also ensures the movement of air (Ac, Ad) inside the channeling means (103). A ground surface suturing nozzle (118) (6) extends the channeling means (103) at its lower suction end (104). It is located facing the ground (6) of the short piece (3a). The sucking nozzle (118) provides in the vicinity of the ground (6) a suction mouth (111) having a suction surface (Sa). The suction surface (Sa) has a substantially vertical inlet section (109). This suction surface (Sa) is an empty annular space, but for a better visualization it is represented in a gray manner. It is represented in flattened expanded form in the lower right corner of FIG. 6. It ensures at floor level (6) air sucking (A) along a substantially horizontal, parallel suction duct (55). and glued to the ground (6) by Coanda effect (C). The suction vein (55) appears in more detail in FIG. 6e. A ceiling surface-blowing nozzle (129) (20) extends the channel means (103) at its upper blowing end (105). It is intended to be located near the ceiling (20). It provides at the top part of a blower (110). The blowing mouth (110) has a porous blast surface (Ss), arranged substantially frontally, bearing laterally on the extreme lateral edges (119a, 119b, 119c, 119d) of the blower mouth (110). This is shown enlarged in the upper right-hand corner of FIG. 6. The blowing mouth (110) provides, through its entire blowing surface (Ss), the production of a primary jet (19) of air (A). ), oriented upwards [or horizontally] so as to reach the ceiling (20) [or be parallel to it], to allow the attachment of the primary blast jet (19) to the ceiling (20) by Coanda effect (C). A decontamination means (127) (operating by filtration and / or destruction) of the contaminating particles (4a, 4b, 4c) of the air (A) is located inside the riser means (103), between the sucking nozzle (118) and the blowing nozzle (129). It partitions internally, on its section (S), the vertical channeling means (103), to force the contaminated air (Ac) to cross, between a contaminated upstream zone (113) and a downstream zone (114) where the air (Ad) is at least partially decontaminated. The decontamination device (101) is characterized in that in addition the effective section (Sae) (shown in the lower right corner) of the suction surface (Sa) of its sucking nozzle (118) is less than. the effective section (Sse) (shown in the upper right corner) of the blowing surface (Ss) of the blower mouth (110). In this way, the average blowing speed (Vs) [average of the air jet velocities on the blowing surface (Ss)] is lower than the average suction speed (Va) [average of the flow velocities of air sucked on the suction surface (Sa)] [Vs <Va].

  It can be seen with reference to FIG. (6) that the device (101) makes it possible to attach the previously treated primary blowing jet (19) to the surface of the ceiling (20). Then, the primary blast stream (19) undergoes at the opposite end of the short piece (3a) a detachment (14) thereby allowing said primary jet (19) to flow on the opposite wall (50). Finally, the primary blast jet (19) undergoes a return to the ground (6) to be attached by Coanda effect (C) and be taken in the continuity of the suction flow (21) attached to the ground (6).

  Referring to Figures 6a and 6b, appear in more detail the inner and outer elements of the independent airborne decontamination device (101). The riser means (103) is included within the outer casing (126) of the device (101). When the device (101) is in operation, the contaminated air (Ac) from the workpiece (3) passes through the ground effect sucking nozzle (118) on the ground (6), extending the channeling means ( 103) at its lower suction end (104) facing the ground (6). There is a suction pressure (Pa). Then the contaminated air (Ac) then passes through a coarse prefilter (120) to be removed from its too large airborne elements (131) can alter the proper operation of the device (101). Contaminated air (Ac) passes inside an acoustic attenuation system (122) to prevent the propagation of airborne and solid noise. It consists of a plurality of parallel baffles (107, 108) located in two groups on either side of the air movement means (106), to prevent the propagation of airborne noise. and solidiens. The means for moving the air (106) is preferably a centrifugal fan type. Then the contaminated air (Ac) is forced through the decontamination means (127) where it is at least partially decontaminated. The decontaminated air (Ad) reaches the upper blowing end (105) and is then released through the blower mouth (110). This decontaminated air (Ad) comes out of the device (101) through the blower (110) where there is a blowing pressure (Ps). The active means of the device (101) can be activated or stopped by means of an on / off system (124). The device (101) is equipped with four wheels (125) attached to its lower part. So that the device (101) is mobile. It can be easily moved from one room (3) to another through the door. A system for controlling the volume flow rate of the device (123) makes it possible to adapt the flow rate as a function of the decontamination needs and the size of the part (3).

  With reference to FIG. 6c, it can be seen that the combined action of the pre-treated primary blowing jet (19) attached by the Coanda effect (C) and the suction flow attached to the ground (21) itself is attached by Coanda effect (C), allows to encompass the entire occupancy zone (2) of the short piece (3a). With reference to FIG. 3, it can be seen that the mobile independent device for airborne decontamination (101) installed in a short piece (3a) and adjusted according to the means fixed by the invention makes it possible to implement in the piece (3a) a primary blow-blown blast (19) and Coanda (C) dual-effect suction flow (21) and further, as demonstrated above, to avoid inclined airflow phenomenon parasite shunt (Fs).

  With reference to FIG. 6d, it can be seen that the device (101) according to the invention allows the vicinity of the ground (6) to suck up as and when they are sedimented (according to the phenomenon described in FIG. suspended contaminant aerosols (4a) and accumulated contaminant aerosols (4b, 4c) located in close proximity to the ground (6) in the thin, highly contaminated upper layer of air (Cc). This is done by means of the suction flow (21) attached to the floor (6).

  The contaminant aerosols (4a, 4b) located near the suction flow (21) and embedded in the suction vein (55) are by suction induction effect (Ias) continuously directed to the suction flow (21) attached to the floor (6) to be evacuated through the suction mouth (111) and undergo the decontamination process.

  The device (101) according to the invention leads to a reduction in the quantity of sedimented contaminating particles (4b, 4c) by continuous evacuation of the latter.

  A consequence is that the soil (6) dirty much less quickly and therefore the room (3) requires less frequent cleaning.

  It also leads to a very significant reduction in the effects of upward movement of the sedimented contaminant particles (4b, 4c) (resulting from convective effects, or turbulence, ... of these particles).

  In addition, there is a virtual elimination of the rising effect of sedimented sedimented particles in suspension or accumulated (4b, 4c) usually due to the existence of the parasitic inclined shunt air flow phenomenon (Fs).

  With reference to FIG. 7, the overall action of decontamination of an independent mobile device for airborne decontamination (101) installed in a short part (3a) and set according to the means fixed by the invention is schematised. It can be seen that this decontamination action takes place differently on the contaminating particles (4): in the upper portion (Cs) of the piece, in the lower portion (Ci) of the piece, in the middle portion (Cm) of the room.

  The coanda (C) double-acting blown primary jet (19) and suction flow (21) encompass the entire area of occupancy (2) of the short piece (3a). All the contaminating particles (4) present in the air (A) of the short piece (3a) undergo the decontamination process.

  In the upper part of the room (Cs), the contaminating particles (4), in the form of suspended contaminating aerosols (4a), are continuously sucked upwards by the induction-inducing effect (Iss) towards the ceiling (20) within the primary blast jet (19). Then they are channeled vertically along the opposite wall (50) before being driven into the intake air stream (21). In the middle portion (Cm), the contaminating particles (4) are essentially those that originate from an occupant-related emission in the area of occupancy (2). Their concentration is very low. In addition, they are continuously driven towards the lower portion of the piece (Ci) by sedimentation effect (5) of gravity. Finally, in the lower portion of the piece (Ci), the contaminating particles (4), in the form of suspended contaminating aerosols (4a), are continuously sucked downwards by suction induction effect (Ias). direction of the soil (6) within the intake air stream (21).

  The absence of parasitic shunt (Fs) inclined air flow, as well as the lower suction induction effect (Ias) caused by the primary suction jet (21), prevents the rise of contaminating aerosols. accumulated (4b) and adhered particles (4c) from the thin, highly contaminated upper layer of air (Cc) in the workpiece portions (Cs, Cm).

  So that the contaminating particles (4) of each portion of the part (Cs, Cm, Ci) are rapidly discharged into the intake air stream (21) before entering the device (101) under the conditions described in FIG. 6d. to be eliminated. The actual decontamination tests performed on an independent airborne decontamination device PLASMAIRTM (101) demonstrate its effectiveness in decontaminating a part (3) with performances close to those of a laminar flow at a cost at least ten times lower.

  A first advantageous embodiment, recommended by the invention, of the independent airborne decontamination device (101) is shown with reference to Figures 6d, 6e and 8b. According to this variant, the sucking nozzle (118) is of the ground suction type (6). That is to say that the suction mouth (111) has a first so-called lower suction wall (132), either in quasi-contact with the ground (6), or formed by the ground (6) him same as described in Figure 6d. The suction mouth (111) has a second so-called upper suction wall (133), substantially horizontal lip-shaped, formed by a portion (134) of the base (137) of the sucking nozzle (118). So that the vertical suction surface (Sav) is free and consists of the annular open vertical surface (136) formed between the base (137) of the sucking nozzle (118) and the ground (6). It ensures at floor level (6) sucking air in a vein (55) glued to the ground, coming from a planar sector flared end suction (138) from the other three walls (50, 140, 144) of the short piece (3a) opposite the vertical treatment wall (52). In addition, the vertical suction surface (Sav) of the sucking nozzle (118) with suction (6) is unobstructed. So that it has a developed area equal to its effective suction area (Sae) as shown in the lower right corner of Figure (8b). It can be seen that the effective suction area (Sae) is smaller than the blow-off cross-section (Sse) of the blow-off area (Ss) of the blow-out mouth (110) (as shown in the upper right-hand corner of FIG. Figure 8b).

  The characteristic arrangement of this first variant makes it possible at the same time to improve the soil effect at the suction level and thus the decontamination action in the thin layer of highly contaminated air (Cc), while allowing limit the effect of inclined parasitic shunt air flow (FS).

  A second advantageous embodiment, recommended by the invention, of the independent airborne decontamination device (101) is shown with reference to FIGS. 8a to 8d. In Figures 8a and 8b we see that the upper blower edge (130) is located at a distance from the ground (Ds) of more than 170cm. It is adapted to a standard height piece of about 250 cm. The respect of this height (Ds) ensures a good progress of the air flow diagram as described in FIG. 6. In FIGS. 8c and 8d, it can be seen that the porous blast surface (Ss) of the blower mouth (110) is provided with a means (163) for directing the blast air streams (164) constituting the primary blast jet (19) mechanically controlled by means of a lever (167). The orientation means (163) makes it possible to adjust the blast angle of incidence (as) of the blower mouth (110) [average on the blast surface (Ss) of the angle of the air ducts blowing (164) the blown primary jet (19) with the horizontal plane (H)] so that it is substantially between an angle of 20 and 70. Figures 8e and 8f show the importance of this second provision recommended by the invention. There is shown in side view, on each of them a device (101) placed in a short part (3a) having the characteristics of those described with reference to Figure (5b). The influence of the adjustment of the blast angle of incidence (as) of its blowing nozzle (110) has been studied by numerical simulation. Figure 8e corresponds to the case where (as = 20). Figure 8f corresponds to the case where (as = 70). It is found that in the recommended setting range (20 <as <70), when the other provisions of the invention are established, then the parasitic shunt air flow phenomenon (Fs) is avoided. Figure 8g corresponds to the case where (as <20). Figure 8h corresponds to the case where (as> 70). It is found that outside the recommended setting range (20 <as <70), when the other provisions of the invention are established, then the parasitic shunt air flow phenomenon (Fs) appears. When (as> 70) we see both a phenomenon of mufti zoning (Z1, Z2) and the appearance of several air loops (B1, B2) as described in the long pieces 3, as well as as the appearance of a parasitic inclined air flow of shunt (Fs). When (a <20) we see the appearance of an inclined parasitic shunt air flow (Fs) alone.

  A third advantageous embodiment, recommended by the invention, of the independent airborne decontamination device (101) is shown with reference to Figure 9b. The blowing section (Sse) of the blower mouth (110) is at least 20% greater than the effective section of the suction surface (Sae) of the sucking nozzle (118). In addition, the flow rate (Qv) of the air moving means (106) is adjusted so that the average blowing speed (Vs) [average of the jet velocities at the outlet of the porous surface of blowing (Ss)] is greater than 0.79 m / s [Vs> 0.79 m / s]. According to these provisions, the average suction velocity (Va) [average of the velocities of the air flow sucked on the inlet suction surface of the porous suction surface] is at least 20% greater than the velocity average blowing (Vs), (Va> 1.2 * Vs). When these particular provisions of the invention are established, then the phenomenon of parasitic inclined shunt air flow (Fs) is avoided.

  On the contrary, FIG. 9a schematically corresponds to the results obtained by numerical simulation when Vs <0.79 m / s and Va <1.2 * Vs. It can be seen in the numerical simulations that, outside the values of thresholds recommended above, we see establishing both a phenomenon of multi zoning (Z1, Z2) and several air loops (B1, B2) as described in long pieces Figure 3 and the appearance of an inclined parasitic shunt air flow (Fs). The characteristic arrangement of this third variant also makes it possible to limit the effect of inclined parasitic shunt air flow (Fs).

  A second preferred embodiment, recommended by the invention, of the independent airborne decontamination device (101) is shown with reference to FIG. 10a. According to this second embodiment, the blowing nozzle (129), on which the porous blast surface (Ss) bears, is widened with respect to the average width of the riser means (103). This widening is measured perpendicular to the vertical plane of symmetry (PV) of the device (101), perpendicular to its front portion (165). It is measured parallel to the first vertical treatment wall (52). Thus, the porous blast surface (Ss) being enlarged, the blowing ratio (RS) increases for an effective suction surface (Sae) remained constant. The blowing speed (Vs) is greatly reduced compared to the suction speed (Va). The attenuation of the effect of inclined parasitic shunt air flow is increased.

  A particular embodiment of this second preferred embodiment is described with reference to FIGS. 15a and 15b. The blowing nozzle (129) has means for enlarging its lateral dimensions (157). This is constituted by at least one [and preferably two, as described in FIGS. 15a and 15b] portion (s) cylindrical (s) flexible (s) porous (s) blowing (159) arranged (s) laterally by means of pipe (103) and in its upper part. They are placed perpendicularly to the vertical plane (PV) of symmetry of the device (101). The porous flexible cylindrical blow portions (159) are sunk vertically when the air moving means (106) is inactive, as depicted in FIG. 15a. But they deploy horizontally under the effect of the pressure (Ps) when the means for moving air (106) is active as described in Figure 15b. Thus they provide a movable blowing surface (Ss) substantially horizontal in the extended position (161).

  Flexible porous blowing cylindrical portions (159) can be manufactured as a glove finger of a reinforced, woven fabric material. The textile material of the thimble is covered with a protective adhesive tape on a generator.

  Then externally applied to the thimble a sealing coating (oilcloth type). Then, remove the protective tape. Thus, most of this glove finger is covered with an airtight sealant material. But a longitudinal range of each porous flexible cylindrical blowing portion (159) is left free of sealing material on a generator so as to let air. In this way, a porous surface (Spa) is cleaned on a fraction of the surface of the thermowell placed on a generator. The remaining surface (SE) is tight on the other fraction. Thus, a blowing surface (Ss) is provided that allows the emission of a primary blast jet (19) along this generator, that is to say parallel to the ceiling (20) when the porous flexible cylindrical portions blowing (159) are deployed. It is advantageous to use a telescopic stiffening means (170), one end of which is placed inside the porous flexible cylindrical blowing portion (159) and the other end of which is integral with the riser means (103). The telescopic stiffening means (170) increases the range of each porous flexible cylindrical blow portion (159) in expanded mode (161). Preferably, the deployment of this telescopic stiffening means (170) is provided by the internal pressure of the device (101). Its folding can be ensured by a spring.

  This leads to a device (101) whose side space is low in the inactive position. He can easily cross a door. On the other hand in active position, the blowing surface (Ss) can be deployed over a width substantially equal to that of the workpiece (3). In this way, an enveloping flow of blowing is provided over the entire width of the piece (3). This leads to much more effective decontamination.

  A third preferred embodiment, recommended by the invention, of the independent airborne decontamination device (101) is shown with reference to FIG. 10b. The porous blast surface (Ss) has a front blast surface (Ssf) extended laterally by two lateral blast surfaces (Sslg and Ssld) formed on the lateral faces of the blast nozzle (135) intended to be placed opposite side walls (140,144) of the room (3). This arrangement increases the effective blowing surface (Sse) and better treat the lateral areas of the room (3) located along the side walls (140, 144). This also contributes to better elimination of the parasitic shunt (Fs) inclined airflow effect.

  A fourth preferred embodiment, recommended by the invention, of the independent airborne decontamination device (101) is shown with reference to FIG. 11. The sucking nozzle (118) of the ground suction type is enlarged at its level. upper wall (139) relative to the average width of the vertical channel means (103) that it extends below. This enlargement is measured perpendicular to the vertical plane of symmetry (PV) of the device (101) perpendicular to its front portion (165). The side walls (141) of the sucking nozzle (118) are therefore further apart.

  A fifth preferred embodiment, recommended by the invention, of the independent airborne decontamination device (101) is shown with reference to Figures 10a, 10b, 12 and 13a, 13b. The sucking nozzle (118) has a tulip flared lower portion (143), placed facing the floor (6). It has also been found by numerical simulation that this arrangement contributes to a better elimination of the effect of inclined parasitic shunt air flow (Fs).

  A sixth preferred embodiment, recommended by the invention, of the independent airborne decontamination device (101) is shown with reference to FIG. 12. The average section of the vertical channeling means (103) at a longitudinal deployment (DL) ( congestion), taken according to the plane of symmetry (PV) of the device (101), less than the longitudinal deployment (DLS) of the sucking nozzle (118). The two dimensions are measured parallel to the vertical plane of symmetry of the device (PV) perpendicular to its front portion (165).

  A seventh preferred embodiment, recommended by the invention, of the independent airborne decontamination device (101) is shown with reference to FIGS. 13a and 13b. The riser means (103) has a lengthwise adjustable pipe portion (147). This portion of adjustable pipe (147) may in particular be constituted by a bellows (149). Such an arrangement makes it possible to adapt the height of the porous blast surface (Ss) as a function of the height (h) of the piece (3). It follows that the device (101) can respond to the architectural variety of parts (3) and thus attach the primary jet (19) to the ceiling (20) by elongated coanda effect (153) as shown in Figure 13b. The narrowing of the height adjustable pipe portion (147) allows the passage of the device (101) through a door of the part (3) in retracted mode (151), as shown in Figure 13a.

  An eighth preferred embodiment, recommended by the invention, of the independent airborne decontamination device (101) is shown with reference to FIGS. 14a and 14b. The device (101) comprises an auxiliary suction nozzle (155) formed in the front part of the channeling means (103). The auxiliary suction nozzle (155) is located about halfway up (about 1 meter from the ground). The auxiliary suction nozzle (155) opens into the channeling means (103) upstream of the contaminating particle removal means (127) in said upstream contaminated zone (Ac). This arrangement allows the decontamination action of the air (A) in the vicinity of the suction auxiliary nozzle (155). An occupant (2) carrying contaminating particles (4) releases suspended contaminating aerosols (4a). This occupant during hospitalization, is positioned in a bed substantially horizontally, its airways are thus located approximately 1m in height. The use of this preferred mode makes it possible, by means of the auxiliary suction nozzle (155), to directly treat the suspended contaminant aerosol emissions (4a) emitted by the occupant in the zone (Cm) such as described in Figure 7.

  Goals and advantages of the invention The object and main advantage of the invention is to attenuate or even eliminate the phenomenon of parasitic shunt air flow, considered by the prior art as necessarily associated with the use of a blowing process by mixing primary blowing jet attached to the ceiling and suction flow attached to the ground, by Coanda effect.

  A second advantage of the invention is to reduce the effects of upward movement of contaminated particles sedimented in a room.

  A third advantage of the invention is to suck as and when their sedimentation aerosols in suspension, and aerosols accumulated in the thin layer of highly contaminated air located close to the ground.

  A fourth advantage of the invention is to reduce the amount of contaminating particles adhered to the floor and consequently the cleaning needs of the room.

  A fifth advantage of the invention is to reduce the concentration of airborne contaminant aerosols in the occupant occupancy zone of a room.

  A sixth advantage of the invention is to reduce the occurrence of diseases by airborne biological contamination in a room.

  A seventh advantage of the invention is to provide an attached jet blast ventilation system, with performances close to those of a laminar flow in terms of decontamination of a workpiece at a reduced cost of one order of magnitude. magnitude.

  An eighth advantage of the invention is to provide a high-cleanliness and mobile airborne decontamination system.

  A ninth advantage of the invention is to be able to quickly bring to places not equipped, the means to fight against occurrences of biological contamination.

  This concerns home medicine as well as the fight against epidemics, civil protection, pharmaceutical and / or food production ...

  A tenth advantage of the invention is to provide a mobile device very suitable for capturing and evacuating airborne contaminant particles close to the ground and to prevent their resuspension. This particularly concerns hypersensitive subjects (allergies).

  An eleventh advantage of the invention is to increase the kinetics of decontamination of a ventilated room by mixing.

  INDUSTRIAL APPLICATIONS OF THE INVENTION The invention makes it possible to optimize at a lower cost the process of decontamination of a part and the evacuation of its contaminating airborne particles. The invention therefore has industrial applications in any type of closed structure requiring decontamination of the air. This concerns in a non-exhaustive way: health, agribusiness, research, transport, breeding, pharmacy, schools ... A particularly adapted application concerns airborne decontamination of health premises, for the protection of patients and hospital staff against the risk of cross-contamination. This concerns in-hospital protection against the risk of contagion of the SARS (Severe Acute Respiratory Syndrome) type ...

  Another application concerns the punctual fight against certain consequences of conventional ventilation in professional, public and domestic premises leading to risks of infections by airborne contaminants transmitted by the air conditioning device. This concerns the local protection, in a room of a ventilated building, against the problems of allergies and / or cross contamination (sick building syndrom) coming from the air conditioning of the building.

  An application can be made in the context of sea or air passenger transport.

  An application can also be made for industries presenting a local biological risk related to the production of a contaminating agent. This may be the case in the pharmaceutical and agri-food industries. This also applies to microbiological research laboratories.

  Another application concerns the protection of high-density farms (chicken, pork, etc.) with a view to ensuring high health status, especially in farms where inputs are limited (breeding farms).

  Another application concerns civil protection in the context of bio-terrorist attacks. A more public application concerns the limitation of the risks of transmission between customers and / or staff of cafeterias and restaurants.

  Another application concerns the prevention of epidemic risks in nurseries, schools and places of small size but of great occupation.

  Finally an application concerns the protection of staff and visitors of dental offices and veterinary clinics ...

  The scope of the invention should be considered in relation to the claims below and their legal equivalents, more than by the examples given above.

Claims (17)

claims   1) A process for ventilating a workpiece (3) by blending, with a primary blast jet (19) attached to the ceiling (20) and a suction flow (21) attached to the floor (6), by a double coanda effect (C ), of the type according to which, a) a primary jet of air (19) previously treated (heated, cooled, decontaminated, moistened, dehumidified, ...) is blown into the piece (3), i) this, through a blowing surface (Ss) located opposite a lateral wall (52), said treatment, in the vicinity of the ceiling (20), ii) in a direction of blowing incidence (Is) [average on the blowing surface (Ss) of the average directions of the portions of the primary jet (19)] oriented towards the ceiling (20) (or parallel thereto), so as to attach by Coanda effect (C) said primary blast jet (19) on the surface of the ceiling (20), b) a sucked sucked air flow (21) with a flow equivalent to the primary jet (19) is drawn through a suction surface (i). (Sa) sensibl vertically located next to the same lateral treatment wall (52), in the vicinity of the floor (6) of the room (3), ii) ensuring at floor level (6) a sucking of the air (A) in a suction line (55) which is substantially horizontal, E parallel and attached to the ground surface (6) by the Coanda effect (C). This ventilation method is characterized in that in addition: the average blowing speed (Vs) [average speed of the portions of the primary air jet (19) on the blowing surface (Ss)] to be lower than the average suction speed (Va) [average speed portions of the sucked airflow (21) on the suction surface (Sa)] [Vs <Va].   A method for ventilating a mixing part, with a primary blast jet (19) and suction flow (21) with a double coanda effect (C), according to claim 1, characterized in that in addition, a) imposes that the effective blowing surface (Sse) is greater than the effective suction surface (Sae).   3) device (101) independent of airborne decontamination of a room (3), for implementing the method according to claim 1 blowing primary blast mixing (19) and suction flow (21) attached to Coanda double-acting device (C), this device (101) being of the type consisting of: a) a vertically disposed vertical channeling means (103) [intended to be disposed substantially parallel and in proximity to a first vertical treatment wall (52); ) of the piece (3) to be treated], this channeling means (103) comprising: i) a first lower suction end (104), located in the lower part in the vicinity and at a distance from the ground (6) of the piece (3), ii) and a second upper discharge end (105), located higher, and intended to be located in the upper part in the vicinity and at a distance from the ceiling (20) of the part (3), b ) means for moving (106) the air (A), disposed in the interior of the riser means (103), and creating an overpressure (AP) between the upper blow end (105) and the lower suction end (104), to allow movement of the air to the and (c) a ground surface-effect nipple (118), extending the channeling means (103) at its lower suction end (104). ) located facing the floor (6) of the room (3), and providing in the vicinity of the floor (6) a suction mouth (111), i) having a suction surface (Sa) inlet section substantially vertical, ii) and ensuring at floor level (6) sucking air (A) in a suction line (55) E substantially horizontal, E parallel and glued to the ground (6) by Coanda effect (C ), d) a ceiling surface effect blowing nozzle (129) (20), extending the channeling means (103) at its upper blowing end (105) [fate e to be located close to the ceiling (20)] and at the top providing a blow-off mouth (110), i) having a porous blow-off surface (Ss), arranged substantially frontally, bearing laterally on the extreme lateral edges (119a 119b, 119c, 119d) of the blow-off mouth (110), ii) and providing through its entire blow-off surface (Ss) the production of a primary jet (19) of air, directed upwards or horizontally [so as to reach the ceiling (20) or be parallel thereto], to allow the attachment of the primary blast jet (19) to the ceiling (20) by Coanda effect (C), e) a means of decontaminating (127) (filtering and / or destroying) air contaminating particles (A), i) located within the riser means (103), between the sucking nozzle (118) and the nozzle blowing (129), ii) internally partitioning, on its section (S), the riser means (103), for ig the contaminated air (Ac) to cross, between a contaminated upstream zone (113) and a downstream zone (114) or air (Ad) is at least partially decontaminated, the decontamination device (101) being characterized in in addition that: f) the effective section (Sae) of the suction surface (Sa) of its sucking nozzle (118) is smaller than the effective section (Sse) of the blowing surface (Ss) of the blow-out mouth (110), so that the average blowing speed (Vs) [average of the air jet speeds (19) on the blowing surface (Ss)] is lower than the average suction speed (Va) [average of the speeds of the intake airflow (21) on the suction surface (Sa)] [Vs <Va].   4) independent device for airborne decontamination (101) of a part (3) according to claim 3, for carrying out the method according to claim 1, for blowing by mixing with primary blowing jet (19) and suction flow fasteners (21) with a double Coanda effect (C), this device (101) being characterized in that in addition, in combination: a) on the one hand, its sucking nozzle (118) is of the suction type on the ground (3), that is to say, whose suction mouth (111): i) has a first so-called lower suction wall (132) E is almost in contact with the ground (3), E is formed by the floor (3) itself, ii) and has a second so-called upper suction wall (133), formed by a portion (134) of the base (137) of the sucking nozzle (118), iii) so that its vertical suction surface (Sa) is free and constituted by the annular open vertical surface (136) formed between the base (137) of the sucking nozzle (118) and the e soil (3), iv) and ensures at ground level (3) sucking air in a vein (55) glued to the ground (6), from a planar sector flared end suction (138). ) from the other three walls (50, 144, 140) of the workpiece (3) opposite the treatment wall (52), b) on the other hand, the vertical suction surface (Sav) of the sucking nozzle ( 118) to the ground (3) is less than the blow-off cross-section (Sse) of the blow-off area (Ss) of the blow-off mouth (110).   5) independent device for airborne decontamination (101) of a part (3) according to claim 3, for carrying out the method according to claim 1 of ventilation by mixing with primary blowing jet (19) and suction flow ( 21) attached by Coanda double effect (C), this device (101) being characterized in that in addition, in combination: a) the upper edge (142) of the porous blast surface (Ss) is located at a distance soil (Ds) greater than 170cm [adapted to a piece (3) of standard height (h) of approximately 250 cm], b) and the porous blast surface (Ss) of the blast nozzle (110) is provided with means (163) for orienting the blast air streams (164) constituting the mechanically adjustable primary blast jet (19) so that the blast angle of incidence (as) of its nozzle of blowing (129) [average on the blowing surface (Ss) of the angle of the blast air streams of the primary jet with the plane hor izontal] is between an angle of 20 and 70 with respect to the horizontal plane (H).   6) independent device for airborne decontamination (101) of a part (3) according to claim 3, for implementing the method according to claim 1 for blowing with primary blowing jet (19) and suction flow ( 21) attached by Coanda double effect (C), characterized in that in addition, in combination: a) on the one hand, the effective section of the blowing surface (Sse) of its blowing nozzle (129) as well as its air-moving means (106) are dimensioned in such a way that the average blowing speed (Vs) of the blowing nozzle (129) [average of the jet speeds at the outlet of the porous blowing surface (Ss )] greater than 0.79 m / s [Vs> 0.79 m / s]; b) and on the other hand, the effective cross-section of the blowing surface (Sse) of its blower mouth (110) is at least 20% greater than the effective cross section of the suction surface (Sae) of its sucking nozzle (118), so that the average suction velocity (Va) [average of the velocities of the intake air flow (21) at the inlet of the porous suction surface (Sa)] is greater than minus 20% at the average blowing speed (Vs)] (Va> 1.2 * Vs).   7) independent device for airborne decontamination (101) of a part (3) according to claim 3, for carrying out the method according to claim 1 for blowing with a primary blowing jet (19) and suction flow ( 21) attached by Coanda double effect (C), characterized in that further said blowing nozzle (129), on which bears said porous blowing surface (Ss), is enlarged relative to. the average width of the vertical channeling means (103) that it extends higher, [measured perpendicularly to the vertical plane of symmetry (PV) of the device (101) perpendicular to its front portion (165)].   8) independent device for airborne decontamination (101) of a part (3) according to claim 3, for implementing the method according to claim 1 for blowing with primary blowing jet (19) and suction flow ( 21) attached by Coanda double effect (C), characterized in that in addition the porous blow-off surface (Ss) has a front blast surface (Ssf) extended laterally by side blowing surfaces (Sslg and Ssld) arranged on the side faces (135) of the blowing nozzle (129) placed opposite the side walls (140, 144) of the part (3).   9) independent device for airborne decontamination (101) of a part (3) according to claim 3, for carrying out the method according to claim 1 for blowing with primary blowing jet (19) and suction flow ( 21) attached by Coanda double effect (C), characterized in that in addition the sucking nozzle (118) is enlarged at its upper wall (139), relative to the average width of the vertical channeling means (103). ) it extends inferiorly [measured perpendicular to the vertical plane of symmetry (PV) of the device (101) perpendicular to its front portion (165)].   10) independent device for airborne decontamination (101) of a part (3) according to claim 4, for implementing the method according to claim 1 for blowing with primary blowing jet (19) and suction flow ( 21) attached by double effect coanda (C), characterized in that in addition the sucking nozzle (118) comprises a lower portion flared tulip (143), placed facing the floor (6).   11) independent device for airborne decontamination (101) of a workpiece (3) according to claim 3, for implementing the method according to claim 1 for blowing with primary blowing jet (19) and suction flow ( 21) attached by Coanda double effect (C), characterized in that in addition the middle section of its vertical channel means (103) to a longitudinal deployment (DL) (bulk), according to the plane of symmetry (PV) of the device (101), less than the longitudinal deployment (DLS) of the sucking nozzle (118) [both measured parallel to the vertical plane of symmetry (PV) of the device (101) perpendicular to its front portion (165)].   12) independent device for airborne decontamination (101) of a part (3) according to claim 3, for implementing the method according to claim 1 for blowing with primary blowing jet (19) and suction flow ( 21) attached by double Coanda effect (C), characterized in that it further comprises an auxiliary suction nozzle (155): a) formed in the front part of the channeling means (103), b) about half height, (of the order of 1 meter from the ground (6)), c) opening in the channeling means (103), upstream of the contaminating particle removal means (127), in said upstream contaminated zone ( ac).   13) An independent device for airborne decontamination (101) of a part (3) according to claim 3, for implementing the method according to claim 1 for blowing with primary blowing jet (19) and suction flow ( 21) attached by Coanda double effect (C), characterized in that furthermore its vertical channeling means (103) comprises an adjustable lengthwise pipe portion (147) (in particular with bellows (149)) to allow adaptation the height of the porous blast surface (Ss) as a function of the height (h) of the workpiece (3) and the attachment of the primary jet (19) to the ceiling (20) by the Coanda effect (C), while allowing the device (101) to pass through a door of the part (3).   14) independent device for airborne decontamination (101) of a part (3) according to claim 3, for carrying out the method according to claim 1 for ventilation by mixing with primary blowing jet (19) and suction flow ( 21) attached by Coanda double effect (C), characterized in that in addition its blowing nozzle (129) comprises means for enlarging its lateral dimensions (157) ensuring a lateral deployment of its blowing surface (Ss) .   15) independent device for airborne decontamination (101) of a part (3) according to claim 14, for carrying out the method according to claim 1 for blowing with a primary blowing jet (19) and suction flow ( 21) attached by Coanda double effect (C), characterized in that in addition its blowing nozzle (129) comprises means for enlarging its lateral dimensions (157) constituted by at least one [preferably two] portion ( s) cylindrical (s) flexible (s) blowing porous (159), a) arranged (s) laterally by means of duct (103) and in its upper part (105), perpendicular to the vertical plane of symmetry (PV) of the device (101), b) and deploying under the effect of the pressure (Ps) by providing a substantially horizontal moving blowing surface (Ss) in the extended position (161).   16) An independent device for airborne decontamination (101) of a part (3) according to claim 15, for implementing the method according to claim 1 for mixing by primary blowing jet (19) and suction flow ( 21) attached by Coanda double effect (C), characterized in that further said porous flexible cylindrical blow portion (159) comprises a) a porous surface (Spa), on a fraction of its surface, to provide a surface of blowing (Ss) and allow the emission of a primary blowing jet (21), b) and a sealed surface (SE) on another fraction.   17) independent device for airborne decontamination (101) of a part (3) according to claim 15, for implementing the method according to claim 1 for blowing with primary blowing jet (19) and suction flow ( 21) attached by Coanda double effect (C), characterized in that it further comprises at least one telescopic stiffening means (170) whose one end is placed inside the porous flexible cylindrical blow portion (159) and the other end is integral with the riser means (103).   18) independent device for airborne decontamination (101) of a part (3) according to claim 17, for implementing the method according to claim 1 for blowing with primary blowing jet (19) and suction flow ( 21) attached by double Coanda effect (C), characterized in that in addition the deployment of this telescopic stiffening means (170) is provided by the pressure inside the device (101).