WO2008024032A1

WO2008024032A1 - Liquid sprayer

Info

Publication number: WO2008024032A1
Application number: PCT/RU2007/000447
Authority: WO
Inventors: Andrey Leonidovich Dushkin; Alexander Vladimirovich Karpyshev; Nikolai Nikolaevich Ryazanczev
Original assignee: Andrey Leonidovich Dushkin; Karpyshev Alexander Vladimirov; Nikolai Nikolaevich Ryazanczev
Priority date: 2006-08-24
Filing date: 2007-08-16
Publication date: 2008-02-28
Also published as: RU2006130489A; RU2329873C2

Abstract

A liquid sprayer comprises a casing (1), a discharge nozzle (2) and a liquid feeding branch pipe (3). A circular passage formed between the inner surface of the casing (1) and the branch pipe (3) is connected to the discharge nozzle (2) through guiding passageways (7). The end part of the liquid feeding branch pipe (3) and the part of the discharge nozzle (2) facing said end part of the branch pipe are formed as conical surfaces. The profiled channel of the discharge nozzle (2) comprises sequentially arranged an inlet circular portion converging in the course of flow and an outlet cylindrical portion joined to the latter. The inlet portion is defined between the conical surface of the end part of the liquid feeding branch pipe (3) and the conical surface of the discharge nozzle (2). The sprayer provides for effective generation of a finely dispersed gas-and-droplet flow with uniform distribution of monodispersion liquid droplets within the flow.

Description

LIQUID SPRAYER

Field of the invention

The invention relates to the equipment for spraying of liquid media, more specifically, to ejection-type sprayers with fine dispersion spraying of liquid droplets, and may be used in firefighting systems, various processes, sanitary ware, liquid fuel combustion apparatuses, air humidification and conditioning equipment, etc.

Background of the invention Various designs of ejection-type liquid sprayers are known nowadays. The main advantage of such sprayers is that they are free from a system for forced feeding of a liquid under high pressure. A working fluid is supplied into ejection-type sprayers from reservoirs or main pipelines under a minimum pressure sufficient for filling a liquid feeding branch pipe.

For example, it is known from the author's certificate SU 1228918 (IPC-4: B05B 7/06, published 07.05.1986) a liquid sprayer comprising a casing and a liquid feeding branch pipe axially located within the casing. A circular passage is defined between the inner surface of the casing and the outer surface of the liquid feeding branch pipe, said circular passage communicating with a gas feeding branch pipe. There are nozzles with converging conical ports on outlet parts of the casing and the liquid feeding branch pipe. Outlet sections of the nozzles . are coplanar with respect to one another. There is an aperture in the liquid feeding branch pipe for communicating the circular cavity with the branch pipe.

During operation of the sprayer, the liquid and the gas are fed under an excessive pressure. The major part of the gas flow is directed through the circular passage while the remaining part of the flow is delivered into the liquid feeding branch pipe cavity through an aperture provided in inlet part of the liquid feeding branch pipe. The gas is preliminarily mixed with the liquid within the branch pipe cavity, the major gas flow is then mixed in the zone adjoining the outlet sections of the nozzles with the gas-and-liquid stream generated in the branch pipe. Thus, the liquid is completely dispersed at the outlet section of the nozzles.

During operation of the given apparatus, a finely dispersed cone of atomized liquid flow is generated at the outlet ends of the nozzles. However, in case of an increased flow rate of one of the components under mixing process, the structure of the generated flow and the uniformity of the liquid spray cone are disturbed. Moreover, the prior art sprayer does not allow an angle of taper of the liquid spray cone to be adjusted. It is known from the description to the author's certificate SU 1470345 (IPC-4: B05B 7/00, published 07.04.1989) an ejection-type sprayer intended for the generation of an aerosol. The sprayer comprises a casing, an outlet converging tube nozzle, a liquid feeding branch pipe axially located within the casing. There is also a circular gas feeding passage within the apparatus. At the outlet end part of the liquid feeding branch pipe there is a conical bushing. Longitudinal grooves are provided on the outer and inner surfaces of the bushing, the depth of the longitudinal grooves increasing towards the end.

The liquid flow is fed by means of a pump into the branch pipe and, while flowing through the grooves provided on the inner surface of the bushing, said flow loses its consistency with the result that vortex formation is created. The gas flow runs through the circular passage towards the discharge nozzle. On flowing of the liquid and gas along the grooves on the inner and outer surfaces of the bushing, the structure of the flows is deformed and their homogeneity is disturbed. As a consequence, an area of contacting of the media under mixing process is increased and the surface energy of the flows is augmented to cause an increase in the spray dispersion ability.

Clogging of the bushing grooves with impurities contained in the gas and liquid flows results in disturbing the symmetry of an opening angle of the atomized liquid flow and also in reducing the dispersion ability and homogeneity of the atomized flow.

In another prior art sprayer described in the patent description SU 677636 (IPC-2: B05B 7/00, issued 30.07.1979), a liquid feeding branch pipe is coaxially located within a casing cavity so as to define a circular gas feeding passage between the casing and the gas feeding branch pipe. The outlet ends of the liquid feeding branch pipe and the casing are formed beveled. The outlet end of the liquid feeding branch pipe and the casing inner part facing said outlet end of the liquid feeding branch pipe define a circular cone-shaped passage converging lengthwise of the sprayer axis. The outlet portion of the gas feeding circular passage has a smaller cross-sectional area in comparison with a cross-sectional area of its inlet portion.

An inlet circular portion of a profiled channel of a nozzle, defined by conical surfaces of the passage and the end part of the liquid feeding branch pipe, is formed converging in the course of flow, the active gas flow being oriented at a right angle to the ejected liquid flow. As a consequence, the generated finely dispersed gas-and-droplet flow is turbulized at an inlet into a cylindrical portion of the discharge nozzle of the apparatus.

As a result of the given phenomenon, the final gas-and-droplet flow generated at the nozzle outlet section has non-homogeneous structure and non-uniform droplets distribution in the flow with regard to their average sizes and concentration by volume. The given phenomenon is associated with the fact that the outlet section of the liquid feeding branch pipe aperture is arranged in front of the inlet into the cylindrical portion of the profiled channel of the discharge nozzle, i.e., within the section wherein the gas flow rate is insufficient for effective ejection and atomization of the liquid, and the gas flow speed vector is essentially oriented at a right angle to the course of flow of the liquid.

During operation of the prior art ejection-type liquid sprayer, the liquid is fed through the branch pipe, and the gas is fed through an elongated feeding channel as a non-turbulized or low-turbulized flow which, while flowing through the circular cone-shaped passage surrounding the liquid flow, atomizes the liquid issued from the branch pipe. It should be pointed out that the sprayer under consideration does not provide for the demanded extent of uniformity in the distribution of the liquid droplets within the atomized flow, as well as the needed structure homogeneity of the atomized flow and monodispersion ability of the finely dispersed fraction of the atomized flow. Moreover, the prior art apparatus does not allow the parameters of the flow generated to be adjusted on changing of the outside conditions, said parameters including a flow rate, a spray cone opening angle and a dispersion ability.

In the utility model certificate RU 40217 (IPC-7: B05B 7/04, published 10.09.2004), a high-dispersion liquid sprayer is disclosed, wherein a gas feeding passage is formed as a pipe with sequentially arranged converging and diverging walls in accordance with the shape of the traditional Laval nozzle. A liquid feeding branch pipe is coaxially located within the gas feeding pipe. The outlet portion of the branch pipe for feeding of the liquid to be ejected is formed as a conical converging tube and is positioned within maximally converged (critical) section of the Laval nozzle.

During operation of the given sprayer, the liquid to be ejected is fed immediately into the profiled channel of the nozzle wherein a sonic speed is reached in the direction similar to that of the gas flow. However, the gas-and-droplet flow is intensively turbulized in the critical section of the Laval nozzle. Turbulization of the generated flow is then enhanced upon expanding thereof in the converging tube portion of the Laval nozzle. Thus, a finely dispersed gas-and-droplet flow is generated at the nozzle outlet section, said flow being characterized by non-homogeneous spatial distribution of liquid droplets and essential droplet size dispersion (from 50 to 500 micron).

It is known from the patent description JP 2005103366 (IPC-7: B05B 7/06, published 21.04.2005) a sprayer comprising a casing and an axial liquid feeding branch pipe with a circular passage defined between the casing and the branch pipe and designed for feeding of air under high pressure. The outlet part of the sprayer casing equipped with the air feeding passage for feeding of air under pressure is formed as a conical converging tube with a cylindrical aperture. The liquid feeding branch pipe has an ultrasonic transducer. The outlet part of the liquid feeding branch pipe is defined by a conical converging portion and a cylindrical portion joined to the latter. The outlet apertures of the air feeding passage and the passage for feeding of the liquid to be ejected are coplanar with respect to one another.

In the liquid filling the feeding branch pipe, low-pressure regions are created by means of the ultrasonic transducer. As a consequence, a cavitational process occurs in the liquid flow and gaseous inclusions are formed. The generated gas-and-liquid mixture is ejected from the outlet aperture of the branch pipe by a high-speed flow of air pumped through the circular passage in the sprayer casing with the help of a compressor. On issuing of the flow into the atmosphere, the bubbles created are expanded and collapsed to generate a finely dispersed atomized liquid flow.

The high-speed gas flow is mixed with droplets of the atomized liquid with the result that the liquid is effectively atomized into fine droplets. However, on mixing of the gas-and- droplet flow with the air flow, a flow is generated at the nozzle outlet section, said flow having non-homogeneous structure owing to a substantial difference in the liquid droplets speed and air flow speed. Non-uniform size distribution of droplets is observed in the generated flow owing to a non-homogeneous distribution of gaseous inclusions in the gas-and-liquid mixture formed in the liquid feeding branch pipe.

The closest prior art to the claimed invention is a liquid sprayer described in the patent description. JP 2000254554 (IPC-6: B05B 1/10, published 19.09.2000). The sprayer comprises a casing with a discharge nozzle, a liquid feeding branch pipe axially located within the casing cavity so as to define a circular passage between the inner surface of the casing and the branch pipe, said circular passage communicating with a gas feeding aperture. The circular passage is communicating with the discharge nozzle through guiding passageways provided on the surface of a circular insert disposed between the liquid feeding branch pipe and the inner surface of casing. The given insert is used in the sprayer design as a gas flow swirler. The guiding passageways are formed tangential and arranged symmetrically around an axis of symmetry of the swirler. The discharge nozzle of the sprayer is formed as a conical tube converging in the course of flow. The end part of the liquid feeding branch pipe at the side adjacent to the inlet of the discharge nozzle and the part of the discharge nozzle facing said end part are formed as conical surfaces. During operation of the sprayer, the gas is charged by means of a compressor into the circular cavity and, while passing through the guiding passageways of the swirler, acquires a rotational motion. The working fluid is delivered under a low excessive pressure into the branch pipe for feeding the liquid to be ejected. In the circular passage of the converging discharge nozzle the high-speed rotating gas flow creates a low-pressure region, into which region the liquid is ejected from the branch pipe to be further mixed with the gas flow. The axially ejected liquid flow comes into contact with a high-speed swirled gas flow.

In the surrounding space, behind the outlet section of the discharge nozzle of the apparatus, at the point where the rotating gas flow intersects with the liquid flow, the liquid is effectively atomized into finely dispersed droplets. However, it should be noted that flowing of the generated gas-and-droplet flow is characterized by a distinctly defined turbulent nature with non-homogeneous droplet distribution through the volume of the spray cone and nonuniform droplet sizes.

The generated gas-and-droplet flow has a circular laminar structure which is due to the joint action of the tangential and axial droplet speed components and variations in the speed component ratio depending on a radial distance from an axis of symmetry of the flow. Moreover, during operation of the sprayer the efficiency in generating a finely dispersed gas- and-droplet flow is reduced owing to additional gas flow energy losses in tangential passageways of the swirler. Among the general limitations of the above prior art apparatuses are insufficient effectiveness in the liquid atomization owing to inefficient consumption of energy for atomization of the liquid flow, complicated design due to the employment of additional systems and units for intensifying the liquid atomization process, and non-uniform liquid droplets distribution in the generated flow as to their sizes and concentration by volume. Furthermore, the prior art apparatuses are characterized by non-homogeneous structure of the gas-and-droplet flow, resulted from the occurrence of large-sized gaseous or liquid inclusions. The gas-and-droplet flow generated using such apparatuses has geometrical size limitations, primarily, with regard to an angle of taper of a spray cone. The prior art liquid sprayers are also characterized by a substantial dependence of parameters of a gas-and-droplet flow on pressure fluctuations and flow rates of gaseous and liquid components, and also on environmental conditions. Disclosure of the invention

The invention is targeted at creation of a sprayer enabling an effective high-dispersion atomization at low liquid flow rates (beginning from 1 g/s) and a low gas working pressure (up to 0.4 MPa). Also, the gas-and-droplet flow generated should be characterized by high spatial homogeneity, monodispersion distribution of droplets sized within a range of from 10 to 40 micron and uniform volume concentration of droplet sizes within the flow. The design of the sprayer should provide for adjustment by mechanical means of geometrical and physical parameters of the generated gas-and-droplet flow including adjustment of the flow rate of the ejected liquid through changing of a gas flow rate. Apart from the above requirements, the sprayer should be simple in design and readily producible.

The technical result to be achieved upon application of the claimed invention includes an increase in the efficiency of generating a finely dispersed spatially homogeneous gas-and- droplet flow, the provision for uniform distribution of monodispersion liquid droplets in the flow and the possibility of adjusting parameters of the gas-and-droplet flow at reduced expenses for the manufacture and operation of the apparatus.

The given technical result is enabled by utilizing a sprayer comprising a casing, a discharge nozzle, a liquid feeding branch pipe axially located within the casing cavity so as to define a circular passage between the inner surface of the casing and the liquid feeding branch pipe, said circular passage being communicated with a gas feeding aperture. The circular passage is connected with the discharge nozzle through guiding passageways, the end part of the liquid feeding branch pipe at the side of an inlet into the discharge nozzle and the part of the discharge nozzle facing said end part of the liquid feeding branch pipe are formed as conical surfaces.

According to the present invention, a profiled channel of the discharge nozzle comprises sequentially arranged an inlet circular portion converging in the course of flow and an outlet cylindrical portion joined to the latter. The inlet portion of the profiled channel is formed between the conical surface of the end part of the liquid feeding branch pipe and the conical surface of the discharge nozzle. The outlet section of the liquid feeding branch pipe aperture is arranged between the outlet section of the inlet conical portion and the outlet section of the outlet cylindrical portion of the profiled channel of the nozzle. The guiding passageways are oriented in parallel with an axis of symmetry of the profiled channel of the discharge nozzle.

A combination of the above essential features provides formation at the inlet of a circular supersonic nozzle of a high-speed non-turbulent flow uniformly distributed over the circular passage. The given nozzle is defined by a passage comprising sequentially arranged an inlet conical portion converging in the course of flow and an outlet cylindrical portion joined to the latter, and a central body, the part of the liquid feeding branch pipe having an outer conical surface serving as said central body.

The gas flow is accelerated in a converging tube part of the circular nozzle to acquire a sonic speed in the nozzle section having a minimum cross-sectional area owing to supercritical pressure fluctuations (for air ΔP_cr~ 0.2 MPa). The critical section of the circular nozzle is located in the region where the inlet conical portion of the nozzle passage is joined with its outlet cylindrical portion. The critical section is restricted at the inner side with the conical surface of the liquid feeding branch pipe. The gas flow is then expanded in the circular diffusion channel between the cylindrical wall of the outlet portion of the nozzle and the conical surface of the liquid feeding branch pipe. As a result of expansion, the gas flow acquires a supersonic speed in the order of MH2-4 (M is Mach number). An abrupt increase in the dynamic component of the gas flow pressure causes reduction in the static component of the pressure to the level below an atmospheric pressure (P_st ~ 0.03...0.08 MPa). Because the outlet section of the liquid feeding branch pipe aperture is located between the outlet section of the inlet conical portion and the outlet section of the outlet cylindrical portion .of the profiled channel of the nozzle, the gas flow energy is utilized with maximum effectiveness for ejecting the liquid from the branch pipe into the cylindrical portion of the profiled channel of the nozzle. The liquid feeding pressure for feeding the liquid into the branch pipe channel may be minimum and is selected on the condition that the branch pipe channel should be filled.

It should be noted that the design of the sprayer allows the liquid to be effectively ejected into the cylindrical channel of the nozzle, just into an unperturbed vortex-free region of the gas flow. Further, on contacting of the liquid flow with the supersonic gas flow having speed vector coinciding with the course of flow of the liquid, there occurs an intensive gas and liquid mixing and dispersion of the liquid flow into individual fine droplets. As a result of the internal nature of liquid dispersion process within the discharge nozzle channel, a spatially uniform finely dispersed gas-and-droplet flow is generated at the nozzle outlet section, with parameters of the flow (a dispersion ability, a flow rate, an opening angle of a spray cone) being essentially independent on the outside conditions. The gas-and-droplet flow generated has a homogeneous structure free from liquid and gaseous inclusions, and predetermined taper angle of the spray cone.

The internal nature of dispersion of the liquid in the region of the supersonic gas flow free from perturbing factors stipulates the monodispersion ability of a finely dispersed fraction of the gas-and-droplet flow. Also, energy losses caused by feeding of the liquid under the excessive pressure and generation of a high-speed gas flow are reduced. The gas pressure at the inlet into the profiled channel of the discharge nozzle may be reduced to 0.4 MPa. The given advantage enables avoiding the employment of systems and units in the design of the liquid spraying apparatus, which are adapted for feeding into the sprayer of the liquid and gas under high pressure.

The demanded angle of taper of the liquid spray cone, the dispersion ability and the concentration by volume of the liquid droplets in the gas-and-droplet flow may be obtained by changing the position of the outlet section of the liquid feeding branch pipe aperture relative to the outlet section of the cylindrical portion of the profiled channel of the nozzle. In order to regulate geometrical and physical parameters of the gas-and-droplet flow generated, it is reasonable that the liquid feeding branch pipe be positioned for axial displacement along an axis of symmetry of the profiled channel of the discharge nozzle.

The diameter d_b of a base of the conical surface of the end part of the liquid feeding branch pipe is preferably selected on the condition that: d_b— (1.3...2.0)d_c, where d_c is diameter of the outlet cylindrical portion of the profiled channel of the discharge nozzle. On observing the given condition, the maximum efficiency of ejecting the liquid into the gas flow is provided by creating optimum conditions for accelerating the gas flow at the inlet conical portion of the profiled channel of the nozzle. An apex angle α of a cone defining the conical surface of the end part of the liquid feeding branch pipe and an apex angle β of a cone defining the conical surface of the inlet portion of the profiled channel of the discharge nozzle are preferably selected on the following conditions: α = 30°...70°; β = 80° ... 100°. Observation of the given conditions also provides for a maximum efficiency in ejecting the liquid into the gas flow due to an optimized process of accelerating the gas flow within a circular gas-dynamic nozzle and creation of a low- pressure zone at the outlet section of the liquid feeding branch pipe. Selection of the angles α and β within the indicated ranges allows the gas flow energy losses to be reduced and vortex formation within the profiled channel of the discharge nozzle to be avoided.

In the preferred embodiment of the invention the cross-sectional area S₃ of the outlet aperture of the liquid feeding branch pipe is selected on the condition that: S_a ⁼ (0.01...0.02)S_c, where S_c is cross-sectional area of the outlet cylindrical portion of the profiled channel of the discharge nozzle. Observation of the given condition allows the gas flow energy losses to be reduced during liquid ejection and the high dispersion ability of the gas-and-droplet flow to be provided (an average droplet size should not exceed 100 micron).

The guiding passageways enabling the uniform distribution of the gas flow circumferentially of the circular profiled channel and the stable vortex-free gas flow along an axis of symmetry of the profiled channel may be formed as longitudinal grooves provided on the inner surface of the casing or on the outer surface of the liquid feeding branch pipe. It is advisable that the length L of the guiding passageways be selected on the condition that:

L= (4...10)d_max, where d_max is maximum cross section of the guiding passageways. The given range of L values is due to provide the minimum energy losses during generation of a uniformly distributed non-turbulized gas flow.

Brief description of drawings

The present invention is explained using an example of implementation of the invention with references to the exemplifying drawings. As an example of implementing the invention is considered a design of an ejection-type liquid sprayer with a movable liquid feeding branch pipe.

The exemplifying drawings illustrate the following: Fig. l is a longitudinal section of a sprayer in full scale of 1 : 1 ; Fig. 2 is a cross section of a sprayer in A-A plane; Fig. 3 is a local view B (see Fig. 1) in full scale of 2:1.

Preferable example of embodiment of the invention

An ejection-type liquid sprayer illustrated in Figs 1 to 3 comprises a casing 1, a discharge nozzle 2, a liquid feeding branch pipe 3 with a bushing 4 positioned on its end part. The branch pipe 3 is axially located within the cavity of the casing 1 so as to define a circular passage 5 between the inner surface of the casing and the branch pipe 3. The circular passage 5 is communicating with a gas feeding aperture 6 provided through the casing 1 and is connected with the discharge nozzle 2 through arcuate guiding passageways 7 formed on the inner surface of the casing 1 (see Fig. 2). According to other versions of embodiment of the invention, the guiding passageways may be formed on the surfaces of the branch pipe 3 and the bushing 4. Eight guiding passageways 7 are arranged symmetrically and oriented in parallel with an axis of symmetry of the discharge nozzle 2. The length L of the guiding passageways 7 is selected on the condition that: L = (4...10)d_max, where d_max^S mm is maximum cross-sectional size of the guiding passageways, and constitutes 4d_max=20 mm. The branch pipe 3 is intended for axial displacement along an axis of symmetry of a profiled channel of the discharge nozzle 2 with the help of a power screw thread provided on the inner surface of the casing 1. The circular passage 5 is sealed by means of a sealing ring 8 located on the branch pipe 3. The discharge nozzle 2 is fixed on the end part of the casing 1 by means of a captive nut 9.

The profiled channel of the discharge nozzle 2 consists of two portions. An inlet circular conical portion 10 is converging in the course of gas flow. The channel of the inlet portion 10 is defined at its one side by a conical surface of the end part of the branch pipe 3, with the bushing 4 serving as said end part, and at its other side by a conical surface of the inlet part of the nozzle 2. In the example under consideration, an apex angle α of a cone defining the conical surface of the bushing 4 is 60°, and an apex angle β of a cone defining the conical surface of the inlet portion of the profiled channel of the nozzle 2 is 84°. The given selection of geometrical characteristics of the inlet portion 10 of the profiled channel of the nozzle determines an optimal shape of the nozzle channel converging in the course of gas flow. An outlet cylindrical portion 11 is joined with the inlet conical portion 10 of the profiled channel. The outlet section of an aperture provided in the bushing 4 of the branch pipe 3 is arranged between the outlet section of the inlet conical portion 10 and the outlet section of the outlet cylindrical portion 11. Diameter d_a of the bushing aperture is 1 mm according to the condition that: S_a=(0.01...0.02)S_c. In the example of embodiment under consideration, S_a-0.8 mm² is cross-sectional area of the outlet aperture of the liquid feeding branch pipe, and S_c=50 mm² is cross-sectional area of the outlet cylindrical portion 11 of the profiled channel of the nozzle 2. The diameter d_c of the cylindrical portion 11 is 8 mm, and the diameter d_b of the conical surface base of the bushing 2 (end part of the branch pipe 3) is 12 mm according to the condition that d_b=(l .3...2.0)d_o. The liquid sprayer operates as follows.

Air is fed under the pressure of 0.4 MPa through an aperture 6 into the circular passage 5 to be further delivered to an inlet of the profiled channel of the nozzle 2 via guiding passageways 7. In the guiding passageways 7, the gas flow is uniformly distributed through the circular passage and the flow is stabilized in the direction parallel to an axis of symmetry of the profiled channel of the nozzle 2. The generated gas flow is then delivered into the inlet circular conical portion 10 of the profiled channel of the nozzle 2. The gas flow is accelerated in the converging inlet portion 10 to a sonic speed in the minimum cross section region of the circular nozzle. Upon passage through the super-critical pressure fluctuation region, the gas flow is then delivered into the cylindrical portion 11 of the profiled channel of the nozzle 2.

Owing to a diverging shape of the cylindrical portion 11 defined by the cylindrical wall of the nozzle 2 and the conical surface of the end part of the bushing 4, the gas flow acquires a supersonic speed of up to the Mach number M=4. An increase in the dynamic component causes reduction in the static pressure within the gas flow at the outlet section of the aperture of the bushing 4 to the value constituting from 0.03 MPa to 0.08 MPa. As a result of the pressure fluctuation created, the liquid filling the branch pipe 3 under a low excessive pressure is ejected in the form of a flow via the outlet aperture of the bushing 4 having the diameter d_a=l mm into the cylindrical portion 11 of the profiled channel of the nozzle 2.

The zone of ejection of the liquid within the supersonic flow passing through the cylindrical channel is free from vortex formation as an effect of perturbing factors. In the cylindrical portion 11 the ejected liquid flow reacts with the stabilized supersonic air flow having a speed vector coinciding with the course of flow of the liquid to cause intensive mixing of the gas and liquid and dispersion of the liquid flow into individual fine droplets.

With internal nature of dispersion of the liquid within the cylindrical channel of the nozzle, the parameters of the generated gas-and-droplet flow do not essentially depend on the outside conditions, therefore a finely dispersed flow is generated at the outlet of the nozzle 2, said flow having a predetermined dispersion ability, a liquid flow rate and an angle of the liquid spray cone.

The parameters of the generated gas-and-droplet flow are adjusted by axial displacement of the branch pipe 3. The displacement of the branch pipe 3 results in changing the passage area of the profiled channel of the nozzle 2 between the conical surface of the bushing 4 and the conical surface of the inlet portion of the profiled channel of the nozzle 2, facing the conical surface of the bushing. The displacement of the bushing 4 results in changing of the gas flow rate through the nozzle 2. Accordingly, the position in the cavity of the cylindrical portion 11 of the outlet aperture of the bushing 4 through which the liquid is ejected is also changed. As a consequence, the flow rate, the dispersion ability and the angle of spray cone of the liquid ejected are changed. On testing of the liquid sprayer having a design corresponding to the example of embodiment of the invention under consideration, a finely dispersed spatially homogeneous atomized liquid flow was produced at the flow rate of 1 g/s, with an average weighted droplet size of 16 micron (within the range of from 4 to 38 micron). The angle of taper of the liquid spray cone dependent on the length of the cylindrical portion of the nozzle constituted from 30° to 60°. The liquid was sprayed at a minimum air inlet pressure of - 0.4 MPa. The gas-and- droplet flow generated had highly uniform distribution of liquid droplets within the flow as to the sizes and the concentration by volume.

Industrial applicability

The ability of the liquid sprayer to generate gas-and-droplet flows having the above properties widens the field of application of said sprayer as part of equipment employed for different purposes, including fire-fighting systems, sanitary wares and also power engineering and processing installations. The sprayer may be used, in particular, in chemical production for spraying of solutions, in gas purification installations, as well as in dust and smoke catching systems, liquid fuel combustion installations, irrigation units, air humidification and conditioning systems, and medical equipment for producing of finely dispersed droplet suspensions.

The sprayer may be also utilized for producing of aerosols from suspended solid particles having diameter from 0.5 to 3 micron by spraying of salt melts and instantaneous evaporation of water from a monodispersion liquid droplet flow.

Claims

1. A liquid sprayer, comprising a casing (1), a discharge nozzle (2), a liquid feeding branch pipe (3) axially located within the casing (1) so as to define a circular passage (5) between the inner surface of the casing and the liquid feeding branch pipe, said circular passage communicating with a gas feeding aperture (6) and being connected to the discharge nozzle (2) through guiding passageways (7), the end part of the liquid feeding branch pipe (3) at the side of the inlet into the discharge nozzle (2) and the part of the discharge nozzle (2) facing thereto being formed as conical surfaces, is characterized in that a profiled channel of the discharge nozzle (2) comprises sequentially arranged an inlet circular portion (10) converging in the course of flow, and an outlet cylindrical portion (11) joined thereto, the inlet portion (10) of the profiled channel of the nozzle is defined between the conical surface of the end part of the liquid feeding branch pipe (3) and the conical surface of the discharge nozzle (2), an outlet section of the aperture of the liquid feeding branch pipe (3) is arranged between an outlet section of the inlet conical portion (10) and an outlet section of the outlet cylindrical portion (11) of the profiled channel of the nozzle, with the guiding passageways (7) being oriented in parallel with an axis of symmetry of the profiled channel of the discharge nozzle (2).

2. The liquid sprayer, according to the claim 1, is characterized in that the liquid feeding branch pipe (3) is designed for axial displacement along the axis of symmetry of the profiled channel of the discharge nozzle (2).

3. The liquid sprayer, according to the claim 1, is characterized in that the diameter d_b of a base of the conical surface of the end part of the liquid feeding branch pipe (3) is selected on the condition that: d_b=(1.3...2.0)d_c, where d_c is diameter of the outlet cylindrical portion (11) of the profiled channel of the discharge nozzle (2).

4. The liquid sprayer, according to the claim 1, is characterized in that an apex angle α of a cone defining the conical surface of the end part of the liquid feeding branch pipe (3) is selected to be within a range of from 30° to 70°.

5. The liquid sprayer, according to the claim 1, is characterized in that an apex angle β of a cone defining the conical surface of the inlet portion of the profiled channel of the discharge nozzle (2) is selected to be within a range of from 80° to 100°.

6. The liquid sprayer, according to the claim 1, is characterized in that the cross- sectional area S_a of the outlet aperture of the liquid feeding branch pipe (3) is selected on the condition that: S_a=(0.01...0.02)S_C5 where S₀ is cross-sectional area of the outlet cylindrical portion (11) of the profiled channel of the discharge nozzle (2).

7. The liquid sprayer, according to the claim 1, is characterized in that the guiding passageways (7) are formed as longitudinal grooves provided on the inner surface of the casing (1) or on the outer surface of the liquid feeding branch pipe (3).

8. The liquid sprayer, according to the claim I₅ is characterized in that the length L of the guiding passageways (7) is selected on the condition that: L=(4...10)d_max, where d_max is maximum cross-sectional size of the guiding passageways.