FR2783310A1 - Snow cannon for ski slopes has mixing chamber with angled water and air inlet injectors - Google Patents

Abstract

The snow cannon has a casing (1) with a mixing chamber (2) having a water inlet (6-10) to inject water under pressure peripherally of the chamber and along its wall. Air inlets (11-16) inject compressed air into the center of the chamber along jets oriented obliquely towards the peripheral wall.

Description

SNOW GUN

  The present invention relates to snow cannons for the production of artificial snow by spraying a mixture

air and water.

  The development of winter sports has given rise in recent years to the need to produce artificial snow to charge or recharge the ski slopes during periods

insufficient snow.

  To date, we have developed three main families

  snow cannons for the production of artificial snow.

  According to the first family, there is at a sufficient height above the ground, at the end of a pole, at least one nozzle of

  air spray and an adjacent water spray nozzle.

  Air and water mix in the atmosphere and form fines

  droplets that turn to snow before reaching the ground.

  According to the second family, water spray nozzles project fine droplets into a flow of air produced by a fan. According to the third family, a two-fluid gun has a mixing chamber in which air and water are sprayed, and the mixture leaves the mixing chamber through an outlet orifice. This third family is for example illustrated by document EP 0 018 280. In such a two-fluid gun, a hollow body comprises a mixing chamber limited by a coaxial peripheral wall and communicating with the outside by an axial outlet orifice. Air intake means inject compressed air into the mixing chamber. Water intake means inject water under pressure into the mixing chamber. The mixing chamber is an elongated tube, with a section significantly smaller than the

  section of the air supply and water supply pipes.

  The devices of the first family, ensuring a spraying at height at the end of a pole, need an inlet air pressure of 8 to 10 X 105 Pa, and a water pressure of at least minus 16 to 20 X 105 Pa. Spraying at height often leads to the snow being dispersed outside the runway surface to be recharged, in the event of wind, even a light one. The support structure necessary to hold the pole leads to a unitary installation

  weighing more than 100 kilograms.

  The second family fan gun devices can deliver 400 to 800 liters of water per minute for a unit installation weight of 400 to 1000 kilograms. These devices also require an inlet water pressure of between 16 and 20 × 10 10 Pa approximately, as well as an electrical connection of 50 kilowatts. It is therefore necessary to provide expensive power cables to bring the energy to the site of

snow production.

  Two-fluid guns of the type of that of document EP 0 018 280 also need a high water pressure, greater than 10 × 10 5 Pa. The inlet air pressure must be

the order of 8 X 105 Pa.

  Thus, all of these known devices require a large infrastructure, most often a pumping station with high pressures at the start to guarantee a pressure of 8 to 16 × 105 Pa at the top of the tracks. The pipes in which the fluids flow must withstand pressures of more than 40 X 105 Pa on average, which makes them heavy and expensive to purchase and set up. The guns themselves are also heavy and bulky, difficult to transport the

  along the rugged ski slopes.

  The devices for producing compressed air capable of reaching the pressures necessary for the guns currently used are relatively expensive, since the pressures are higher than those of the versatile compressors generally used on construction sites for feeding jackhammers. There is therefore a permanent need for a device for producing artificial snow which can operate with reduced air and water pressures, and which is of reduced weight and size to facilitate its transport to the

  snow producing areas along the ski slopes.

  The problem proposed by the present invention is therefore to design a new snow cannon structure making it possible to produce good quality snow from a lower pressure of air and water at the inlet, so as to be satisfy a lighter infrastructure for the production of air and water under pressure, and so as to use transport pipelines

  lighter and less expensive air and water.

  The invention results from the surprising observation that it is possible to produce artificial snow from lower pressures of air and water thanks to a particular form of chamber for mixing air and water under pressure, larger diameter, in which we create a maximum of turbulence while undergoing a reduced pressure drop, and we

  brings the mixture out through an annular orifice.

  To achieve these and other objects, the present invention provides a snow cannon for the production of artificial snow by spraying a mixture of air and water, comprising a hollow body having a mixing chamber oriented along a longitudinal axis. , bounded by a lateral peripheral wall and communicating with the outside via a front outlet orifice, having air intake means for injecting compressed air into the mixing chamber, and having inlet means d water for injecting pressurized water into the mixing chamber; according to the invention: - the mixing chamber has a cross section greater than that of the outlet orifice, and is connected to said outlet orifice by a narrowing, - the water intake means are shaped to inject the pressurized water in one or more jets in the peripheral zone of the mixing chamber along the peripheral wall and in a rotary movement around the longitudinal axis of the mixing chamber, - the air intake means are shaped for injecting the compressed air into the central zone of the mixing chamber in one or more jets directed obliquely towards the peripheral wall, so that the jet (s) of compressed air penetrate the rotary stream (s) of water in the mixture, - the outlet orifice is annular in shape, around a central core. Thanks to such a mixing chamber structure, the two-fluid gun according to the invention can be compact and light, according to a weight of 2 to 3 kilograms, which is easily moved. Such a gun is capable of operating at variable flow rates as a function of the outlet orifice section, and with water inlet pressures of the order of 4 × 105 Pa and an air pressure of order of that produced by the usual site compressors for supplying jackhammers. Under certain conditions, it is possible to snow with an inlet water pressure which can go down to around 3 X 105 Pa. The pressure

  compressed air is slightly higher than that of water.

  Thanks to the annular shape of the outlet orifice, the mixture of air and water exits through the orifice in tubular and rotating form, and it pushes the outside air forward, inducing a central depression which favors the entry of outside air currents towards the center. This probably promotes the fragmentation of the droplets and causes better heat exchange with the outside air and the droplets. The mixture is

  cools faster and freezes quickly before touching the ground.

  Also, as the mixture changes pressure between the mixing chamber and the outside, the air expands rapidly and separates the parts of water which are close to it. This favors

  likely the formation of snowflakes.

  According to one embodiment, the water intake means comprise a plurality of helical channels distributed in

  periphery around the longitudinal axis.

  The helical channels can be connected, upstream, to an annular water distribution chamber communicating with a

peripheral water inlet.

  According to one embodiment, the air intake means can comprise a plurality of air channels. The air channels can for example be divergent to direct the air obliquely

towards the peripheral wall.

  In practice, the air channels can communicate with the mixing chamber by injection orifices distributed along a ring on which abuts an adjustment plate pierced with an annular series of through holes, the adjustment plate possibly being pivoted about the longitudinal axis between a fully open position in which each air channel outlet orifice is opposite a through hole in the adjustment plate, and partial shutter positions in which the plate adjustment is slightly pivoted about the longitudinal axis to at least partially offset the plate holes relative to the outlet openings of the air channels. This creates air turbulence entering the mixing chamber, and also regulates the air flow. Indeed, in certain cases, it is useful to be able to reduce the air flow which arrives in the mixing chamber to reduce the risks of freezing at

leaving the room.

  Preferably, the outlet orifice is limited internally by the central core and is limited externally

  by an internal radial annular lip.

  According to an advantageous embodiment, the central core is elongated longitudinally and is adjustable in longitudinal position along the longitudinal axis, and its cross section is variable longitudinally. It is thus possible to adjust to a certain extent the diameter of the mixing jet a few centimeters from the outlet, to adapt to external humidity and temperature conditions to optimize the quality of the

  to set the shooting distance.

  In this case, according to one possibility, the central core can also comprise several external radial annular ribs,

  of different diameters, separated by a frustoconical section.

  Alternatively, the central core can advantageously be conical, allowing continuous adjustment of the section of the orifice

Release.

  An additional function of the central core can be obtained by providing a central core in the form of a reversible nut engaged by screwing and selectively locked in the axial position on an axial threaded rod of the body. By the same central core, it is thus possible to substantially modify the shape of the outlet orifice. The larger the section of the outlet, the higher the possible flow rate for a given pressure of fluids at the inlet. Depending on the shape of the passage between the mixing chamber and the outlet, it is possible to create an average speed of exit of the air and water masses, of divergent or convergent shape, and thus to adapt the spraying for the formation.

  optimized snow and shooting distance setting.

  For a given outlet port shape, it is naturally possible to modify the flow rate by varying the fluid pressure at the inlet. Also, for a given inlet pressure, one can choose the most suitable outlet orifice shape to produce quality snow according to the

  external humidity and temperature conditions.

  Other objects, characteristics and advantages of the

  present invention will emerge from the following description of modes

  of particular embodiments, made in relation to the appended figures, among which: - Figure 1 is a side view in longitudinal section of a snow cannon structure according to an embodiment of the present invention; - Figure 2 is an end view of the snow cannon of Figure 1; - Figure 3 is a front sectional view along the plane A-A of Figure 1; and - Figure 4 is a top view in partial horizontal section

according to plan B-B of figure 1.

  In the embodiment illustrated in the figures, a snow cannon according to the invention comprises an elongated hollow body 1, for example generally cylindrical, having a mixing chamber 2 limited by a coaxial peripheral wall 3 and communicating

  with the outside through a front outlet 4.

  The hollow body 1 generally develops along a longitudinal axis I-I, the peripheral wall 3 is cylindrical of revolution and coaxial around the longitudinal axis I-I, and the outlet orifice 4 is arranged symmetrically along the axis

longitudinal I-I.

  It will however be possible, without significant loss of efficiency, to provide an outlet orifice 4 offset from the axis I-I, which is not symmetrical, and to provide a mixing chamber 2 which is not

of revolution.

  The mixing chamber 2 has a cross section greater than that of the outlet orifice 4, and is connected to said outlet orifice 4 by a narrowing 5, for example a

  frustoconical narrowing as illustrated in FIG. 1.

  In the mixing chamber 2, the water is introduced by means of water intake comprising a plurality of helical channels such as channels 6, 7, 8, 9 and 10, distributed

  regularly on the periphery around the longitudinal axis I-I.

  Thus, the channels 6-10 constituting the means for admitting pressurized water are shaped to inject the pressurized water into the peripheral zone of the mixing chamber 2 along the peripheral wall 3 and in a rotary movement around the longitudinal axis II of the mixing chamber 2. For example, the channels 6-10 consist of helical peripheral grooves distributed around a central cylindrical piece forming an intermediate transverse wall 21 and engaged in a tube forming

the peripheral wall 3.

  Compressed air is introduced into the mixing chamber 2 by air intake means comprising a plurality of air channels such as channels 11, 12, 13, 14, 15 and 16, distributed in

  the central zone of the hollow body 1 around the longitudinal axis I-I.

  For example, as illustrated in FIG. 1, the air channels 11-16 are divergent and form an angle of about 15 degrees with the longitudinal axis II, gradually moving away from the longitudinal axis II as they approach the room of

mixture 2.

  Thus, the air intake means constituted by the divergent air channels 11-16 are shaped to inject compressed air into the central zone of the mixing chamber 2 according to several jets directed obliquely towards the peripheral wall 3. From so the compressed air jets penetrate the water flow (s)

  rotary in the mixing chamber 2.

  Upstream, the helical water inlet channels 6-10 connect to an annular water distribution chamber 17, externally limited by an external cylindrical wall 18 extending rearward the peripheral wall 3 of the mixing chamber 2, and internally limited by an inner cylindrical wall 19. The inner cylindrical wall 19 is connected to the outer cylindrical wall 18 upstream by a rear crown 20, and downstream by the intermediate transverse wall 21 comprising the helical channels 6- 10 and the divergent channels 11-16. In FIG. 4, the external cylindrical walls 3 and 18 are cut along the plane B-B of FIG. 1, while the intermediate transverse wall 21 is not cut to reveal, according to its periphery, the helical channels such as

the helical channels 6 and 8.

  Upstream, the air channels 11-16 are connected to an axial air supply pipe 22, externally limited by the

inner cylindrical wall 19.

  The axial air intake pipe 22 communicates with a central air inlet 23, while the annular water distribution chamber 17 communicates with a peripheral water inlet 24. As can be seen in particular in FIG. 3 , the air channels 11-16 communicate with the mixing chamber 2 by injection orifices distributed in a coaxial ring on the

  downstream front face of the intermediate transverse wall 21.

  According to an embodiment as illustrated in FIG. 1, an adjustment plate 25, pierced with an annular series of through holes, bears against the coaxial ring of the intermediate transverse wall 21. The adjustment plate 25 can be pivoted about the longitudinal axis II between a fully open position in which each air channel outlet orifice 11-16 faces a through hole of substantially the same section of the adjustment plate 25, and partial shutter positions in which the adjustment plate 25 is slightly pivoted about the longitudinal axis II to at least partially offset the plate holes relative to the outlet orifices of the air channels 11-16. The adjustment plate 25 thus makes it possible both to create turbulence in the air entering the

  mixing chamber 2, and adjust the air flow.

  As seen in Figures 1 and 2, the orifice of

  outlet 4 is of annular shape, around a central core 26.

  In the illustrated embodiment, the central core 26, engaged in the outlet orifice 4, comprises a first external radial annular rib 27, and a second external radial annular rib 28 of diameter greater than that of the first external radial annular rib 27 from which it is separated by a

tapered section 29.

  The central core 26 is preferably adjustable in longitudinal position along the longitudinal axis I-I. For example, as illustrated in FIG. 1, the central core 26 is in the form of a reversible nut engaged by screwing and locked selectively in

  axial position on an axial threaded rod 30 of the body 1.

  For example, the axial rod 30 is screwed into a threaded axial bore 31 of the intermediate transverse wall 21. By more or less significant screwing of the central core 26 on the threaded axial rod 30, the longitudinal position of the central core 26 is adjusted relative to an internal radial annular lip 32 of the

  body 1 which externally limits the outlet orifice 4.

  Thus, the outlet orifice 4 is limited externally by the internal radial annular lip 32 of the body 1, and internally by the central core 26. Depending on the position of the central core 26 along the longitudinal axis II, it is thus possible to modify the shape of the outlet orifice 4. For example, in the position illustrated in FIG. 1, the outlet orifice 4 is substantially limited by the internal radial annular lip 32 and by the first rib

  external radial annular 27 of the central core 26.

  If the central core 26 is turned over, an outlet orifice 4 of smaller cross section can be produced, limited by the internal radial annular lip 32 and by the second annular rib

  external radial 28 of the central core 26.

  In the embodiment illustrated in FIG. 1, the axial rod 30 also serves to hold the adjustment plate 25: the rod 30 passes through a central hole in the adjustment plate 25, and the adjustment plate 25 is held pressed against the transverse wall intermediate 21 by a tightening nut 33 screwed on

the axial rod 30.

  The present invention is not limited to the embodiments which have been explicitly described, but it includes the various variants and generalizations thereof contained in the field.

of the claims below.

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Claims (8)

  1 - Snow cannon for the production of artificial snow by spraying a mixture of air and water, comprising a hollow body (1) having a mixing chamber (2) oriented along a longitudinal axis I- I, limited by a lateral peripheral wall (3) communicating with the outside via a front outlet (4), having air intake means for injecting compressed air into the mixing chamber (2), and having water intake means for injecting pressurized water into the mixing chamber (2), characterized in that: - the mixing chamber (2) has a cross section greater than that of the outlet orifice (4), and is connected to said outlet orifice (4) by a narrowing (5), - the water intake means (6-10) are shaped to inject water under pressure in one or more jets in peripheral zone of the mixing chamber (2) along the peripheral wall (3) and in a rotary movement around the longitudinal axis (II) of the mixing chamber (2), - the air intake means (11-16) are shaped to inject compressed air into the central zone of the mixing chamber (2) according to one or more jets directed obliquely towards the peripheral wall (3), so that the compressed air jet (s) penetrate the rotary water flow (s) in the mixing chamber (2), - the outlet ( 4) is annular in shape, around a nucleus central (26).   2 - Snow cannon according to claim 1, characterized in that the water intake means (6-10) comprise a plurality of helical channels (6-10) distributed around the periphery around the longitudinal axis (I-I).   3 - Snow cannon according to claim 2, characterized in that the helical channels (6-10) are connected, upstream, to an annular water distribution chamber (17) communicating with a peripheral water inlet (24).   4 - Snow cannon according to any one of   Claims 1 to 3, characterized in that the intake means   comprise a plurality of air channels (11-16) distributed in the central region of the hollow body (1) around the axis longitudinal (I-I).   - Snow gun according to claim 4, characterized in that the air channels (11-16) are connected, upstream, to an axial air supply pipe (22) communicating with an inlet central air (23).   6 - Snow cannon according to one of claims 4 or 5,   characterized in that the air channels (11-16) communicate with the mixing chamber (2) by injection orifices distributed along a ring on which abuts an adjustment plate (25) pierced with a series annular through holes, the plate   adjustment (25) which can be pivoted about the longitudinal axis (I-   I) between a fully open position in which each air channel outlet orifice (11-16) faces a through hole in the adjustment plate (25), and partial shutter positions in which the adjustment plate (25) is slightly pivoted about the longitudinal axis (II) to at least partially offset the plate holes relative to the   air channel outlet holes (11-16).   7 - Snow cannon according to any one of   Claims 1 to 6, characterized in that the outlet (4)   is internally limited by the central core (26) and is limited   externally by an internal radial annular lip (32).   8 - Snow gun according to claim 7, characterized in that the central core (26) is elongated longitudinally and is adjustable in longitudinal position along the longitudinal axis   (I-I), and its cross section is variable longitudinally.   9 - snow cannon according to claim 8, characterized in that the central core (26) further comprises several external radial annular ribs (27, 28), of different diameters,   separated by a frustoconical section (29).   - Snow cannon according to one of claims 8 or 9,   characterized in that the central core (26) is a reversible nut engaged by screwing and locked selectively in the axial position on   an axial threaded rod (30) of the body (1).