US3923247A

US3923247A - Snowmaking device

Info

Publication number: US3923247A
Application number: US488642A
Authority: US
Inventors: Jeffery A White
Original assignee: Command Engineering International Ltd
Current assignee: Command Engineering International Ltd
Priority date: 1974-07-15
Filing date: 1974-07-15
Publication date: 1975-12-02
Anticipated expiration: 1992-12-02
Also published as: FR2278407B3; FR2278407A1; CA1000066A

Abstract

The invention relates to a snowmaking device of the type comprising a gun having an outer water conduit, an inner air conduit and a convergent-divergent nozzle connected thereto and wherein the divergent portion of the nozzle includes a circular restricter. Water undergoes pre-atomization at the point of intersection of the convergent and divergent portions of the nozzle and final and more uniform atomization as it issues downstream from the restricter in the divergent section of the nozzle.

Description

United States Patent 1191 White 1 Dec. 2, 1975 1 1 SNOWMAKING DEVICE Jeffery A. White, London, Canada [73] Assignee: Command Engineering (International) Ltd., London, Canada 221 Filed: July15, 1974 1211 Appl. No.: 488,642

[75] Inventor:

[52] US. Cl. 239/14; 239/407; 239/432; I 239/434.5; 239/456 [51] Int. Cl. F25C 3/04; BOSB 7/12; BOSB 1/32 [58] Field of Search 239/25, 14, 407, 416.5, 239/423, 424, 427, 432, 434.5, 456-458, 505,513,514, 592, 417.5

[56] References Cited UNITED STATES PATENTS 1,631,167 6/1927 Tereau 239/456 2,676,471 4/1954 Pierce, Jr... 239/2.5

2,859,728 11/1958 Hobdy 239/514 X 2,969,923 1/1961 Fremion 239/514 X 3,464,625 9/1969 Carlsson 239/25 3,494,559 2 1970 Skinner 239/14 x 3,680,781 8/1972 Lincoln... 239/4345 x 3.829.013 8/1974 Ratnik 239/14 3,831,844 8 1974 Tropeano et a1. 239/14 Primary ExaminerEvon C. Blunk Assistant ExaminerAndres Kashnikow Attorney, Agent, or Firm-Whee1er, Morsell, House & Fuller [57] ABSTRACT The invention relates to a snowmaking device of the type comprising a gun having an outer water conduit, an inner air conduit and a convergent-divergent nozzle connected thereto and wherein the divergent portion of the nozzle includes a circular restricter. Water undergoes pre-atomization at the point of intersection of the convergent and divergent portions of the nozzle and final and more uniform atomization as it issues downstream from the restricter in the divergent section of the nozzle.

6 Claims, 2 Drawing Figures SNOWMAKING DEVICE BACKGROUND OF THE INVENTION This invention relates to a novel snowmaking device and more particularly, to an improved snowmaking nozzle.

DESCRIPTION OF THE PRIOR ART There are two principal types of snowmaking devices currently in use. The first type of snowmaker atomizes water discharged therefrom externally thereof through impinging action brought about by one or more air discharge streams directed towards the water flow. The other type effectively atomizes discharge water within the nozzle of the snowmaker. While the present invention concerns snowmaking devices of the last mentioned variety, both types have undesirable characteristics as discussed below.

Conventional snowmaking equipment requires a relatively high air to water discharge ratio, the amount of air necessary to produce artificial snow being proportionate to the ambient air temperature and the water temperature. For example, while at F, an airwater ratio measured in cubic feet of air per minute over US. gallons of water pre minute of 4:1 may be suitable, at a temperature of approximately 28F, provided the water temperature remains constant, a ratio of :1 is not uncommon. The reason for increased air at increased temperatures is due to the fact that it is the attendant air discharge which is responsible for effecting sufficient heat loss from the atomized water in order to freeze the water particles.

An additional shortcoming inherent in conventional snowmaking equipment is the operational noise produced at the nozzle of the snowmaker. This noise, which is unpleasant to both residents and guests of ski resort communities, increases as the amount of air is increased. Moreover, compared to the cost of producing and maintaining water under pressure throughout a snowmaking system, the cost of producing associated pressurized air is significantly higher.

Due to the unique design of my snowmaking device and more particularly, the nozzle for same, I have found that it is now possible to produce an equivalent amount of artificial snow to that formerly produced using much less air. Surprisingly, l have also found that the operating noise of a snowmaking device using my novel nozzle is materially reduced. Further, my nozzle design has been found to produce atomized water particles which are of a more uniform size than that previously obtainable in snowmaking devices of the internal mixing variety whilst, at the same time, retaining a snow throw capability substantially equal to conventional internally mixing snowmaking nozzles but over a wider pattern. I have also found that my improved nozzle remains operational under increased air and water pressures which were previously considered unacceptable in producing artificial snow.

SUMMARY OF THE INVENTION The novel snowmaking device of my invention is of the type having a gun section which includes an outer water discharge conduit, an inner coaxial air discharge conduit and a coaxial nozzle connected to the downstream end of the gun. However, unlike prior nozzles, my nozzle has an upstream conically converging section or collector and a downstream conically diverging section or horn wherein the horn is provided with a restricter or choke, the prime purpose of which is to function as a mechanical atomizer. The restricter, being circular in cross-section relative to the longitudinal axis of the nozzle, defines an annular gap with the wall of the horn. For reasons which will become apparent hereafter, the area of the annular gap should be less than the area of the circular opening or venturi which is the orifice positioned at the point where the walls of the collector and horn meet.

While the restricter may be supported in position from the wall of the horn, I prefer to support it on a stem which is connected to the gun internally of the water discharge conduit and which extends through the venturi of the nozzle. This facilitates easy removal and replacement of the restricter should such be required or should a restricter of a different size or configuration be desirable for a given operating pressure in the system at a given temperature. Although the restricter may be disc-like in shape, in its preferred form, it has an upstream diverging nose portion which defines with the wall of the horn as it extends towards the radial extent of the restricter an annular passageway which diminishes in size. This constricting effect downstream of the venturi facilitates a generally uniform acceleration of the already once accelerated water which has passed through the venturi and been effectively pre-atomized at that point.

The downstream side of the restricter can also be advantageously provided with a converging tail portion which improves or enhances an intermixing of discharge air and the further and more uniformly atomized water issuing from the annular gap immediately surrounding the restricter.

I have also found that by selectively positioning or adjusting the restricter in the horn section to thereby increase or decrease the annular gaps thereabout, the operating air-water capacity of a particular snowmaker can be controlled so that at a given temperature, maximum snowmaking capability is achieved. Previously it was necessary to vary the size of nozzle to meet the operating capacity.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings which illustrate a preferred embodiment of my invention,

FIG. 1 illustrates, in longitudinal cross-section, a snowmaking device comprising a snowmaking gun and the improved nozzle, and,

FIG. 2 is a cross-section of the snowmaking gun taken along the lines IIII of FIG. 1.

DETAILED DESCRIPTION Reference Number 1 represents the snowmaking gun and 2 the nozzle. The gun itself has a central air conduit 3 with tubular wall 3' about which is located water jacket 4. The water generally indicated at 30 by broken lines within the water jacket functions as an insulator to minimize the likelihood of freezing and clogging of condensate in pressurized air in air conduit 3. Water inlet conduit 5 which communicates with the water jacket is connected to a water supply hose (not shown). Air conduit 3 is similarly connected to an air pressure supply hose. The water jacket conduit 4 terminates forward of water and air discharge ends 6, and 7, respectively, of the gun as illustrated, in order to facilitate coupling of nozzle 2 thereto at threaded connection 8.

An air-water seal is provided between the gun 1 and the nozzle 2 by means of O-ring 9.

As best seen in FIG. 2, webs 11 in the vicinity of water and air discharge ends 6 and 7 extend radially inwardly from jacket 4 so as to support restricter mounting pin or stem 12 centrally of and coaxial with air conduit 3. With reference to FIG. 1, it will be seen that the webs are held in position by extending into a recess in jacket 4 and by abutment with nozzle 2. Nozzle 2 comprises a conically converging upstream collector chamber or section 13 and a downstream conically diverging discharge portion or horn 14. The wall 15 of collector chamber 13 converges in the direction of the stream flow while wall 16 of horn l4 diverges. A circular space or venturi is located at point 17 where the walls 15 and 16 of the collector and horn 13 and 14 meet.

Positioned within the horn 14 is restricter 20. As illustrated, the restricter has an upstream conically divergent nose portion 21- and a downstream conically diverging tail portion 22. Wall 23 of nose portion 21 diverges outwardly so as to define with wall 16 an annular passageway 24 which decreases in area in the direction of the stream flow and terminates at annular gap 25. It will be appreciated that nose portion 21 need not be conical in shape in order to define with the wall of the born a passageway which decreases in cross-sectional area along its length and may, for example, be in the shape of a skirt or hemisphere. The tail portion 22 of restricter is preferably bullet-like in appearance in order to improve internal eddying of the discharge stream for the purpose of effecting heat exchange between the air-water discharge mixture and consequent freezing of the water particles.

While it is necessary for proper operation to provide an annular gap 25 which has an area which is less than the area of venturi 17, with reference to FIG. 1 it will be observed that in fact the area of the venturi is less than its diameter area due to the presence of stem 12 extending therethrough. In a case where the restricter is supported from the wall of the horn (not shown) then the permissible opening of the annular gap would be greater than that allowable using a stem arrangement for supporting the restricter. In operation, it may also prove desirable to vary the opening of the annular gap within the area constraints above described in order to obtain the optimum air-water snowmaking capability for a given pressure of the snowmaking system at a given ambient air and water temperature. This can be achieved by adjusting the restricter or nozzle inwardly or outwardly relative to the other in a conventional manner such as by using a locking thread adjustment connector 26 as shown.

In operation, supply water in the gun and nozzle generally indicated by broken lines and Reference Numeral 30 is caused to move along wall 15 of the collector as it is discharged from point 6. Because the flow of water is constricted inwardly and on its innermost side is subjected to a central core of pressurized air issuing from air discharge 7, the water tends to thin out and accelerate along wall 15 to venturi 17 where, through the impinging action of the pressurized air, it undergoes a shearing or tearing action so as to form air and preatomized water particles generally indicated at 31. As this air and pre-atomized water 31 proceeds along passage 24 it undergoes or experiences further acceleration due to the convergence of the passageway. At annular gap 25 secondary or final and more uniform atomization of the pre-atomized water takes place, the finally atomized water being generally indicated at 32. This two stage atomization effectively reduces the water particles or droplets to a size sufficiently small enough that upon release to the ambient air freezing of same through heat exchange with the pressurized air is better achieved.

While not wishing to be limited to any particular theory as to why my novel snowmaking nozzle functions materially better over other known snowmaking nozzles of the internal mixing type, it is believed that a fair proportion of the energy in the compressed air is used up in atomizing the water. As a consequence, there is less free energy available to effect sufficient heat exchange between the air and water particles to cause freezing of the latter. The introduction of a restricter is believed to facilitate atomization mechanically thereby rendering available more free air energy so as to effect its prime function which is thermal exchange with the atomized water and its projection.

What I claim as my invention is:

1. In a snowmaking device of the type comprising a gun section having an outer water discharge conduit, a coaxial inner air discharge conduit and a nozzle connected to the downstream end of said gun which is coaxial therewith, the improvement comprising a nozzle having an upstream conically converging collector section and a downstream conically diverging horn section, said inner air discharge conduit being larger than the smallest diameter of said conically converging collector section and directed coaxially at said collector section to effect a first acceleration and atomization of water entering said section, a circular restricter positioned internally of said horn section and coaxial therewith whereby the wall of said horn section and the radial extent of said restricter define an annular gap, the area of said annular gap being less than the area of the circular opening defined between the collector section and the horn section to effect a second acceleration and atomization of water particles.

2. The snowmaking device as claimed in claim 1, wherein said circular restricter includes an upstream divergent nose portion whereby the annular passageway defined between the walls of the horn section and said divergent portion diminishes in the direction of water and air flow.

3. The snowmaking device as claimed in claim 2, wherein the divergent portion of said restricter is one of a cone, skirt and hemisphere.

4. The snowmaking device as claimed in claim 3, wherein said restricter is held in position by means of a stem coaxially connected at one end thereto and which extends through said circular opening and is connected to said gun.

5. The snowmaking device as claimed in claim 4, wherein said circular restricter includes a downstream convergent tail portion.

6. The snowmaking device as claimed in claim 5, wherein the restricter is selectively adjustable relative to the nozzle to thereby increase or decrease the annular gap.