[0001] The invention relates to a snow making apparatus, comprising an open-ended shroud,
a fan for directing a flow of air through said shroud, a plurality of water spraying
nozzles arranged circumferentially about said shroud and adapted to spray water forwardly
along with said flow of air.
[0002] The manufacture of man-made snow at commercial ski areas is widely practiced, as
a means for not only extending the useful season of the ski area, but also improving
the quality and uniformity of the surface during the primary season. Typically, in
the production of made-made snow, the snow making areas are furnished with supplies
of compressed air and water under pressure. Usually, these are in the form of permanent
distributional installations, with provisions being made for connection of the snow
making equipment at appropriate locations. US-A-2 676 471 is representative of such
an installation.
[0003] One of the common techniques for the production of man-made snow is the mixture and
discharge of water and compressed air through a simple discharge gun as, for example,
the type shown in US-A-3 716 190. The water is partially atomized within the gun,
when it is mixed with the high pressure compressed air, and the high velocity discharge
of the water/compressed air mixture serves to complete the atomization and to convey
the atomized water particles then an appropriate distance from the discharge nozzle.
Snow making guns of this type are simple and reliable, but suffer a disadvantage in
requiring a substantial consumption of compressed air, which is an expensive component
of the snow making process.
[0004] Another common form of snow making apparatus incorporates an engine drive fan, which
directs a stream of air at relatively high velocity through a confining shroud and
outcover the snow making area. A plurality of atomizing water nozzles are distributed
around the periphery of the shroud, discharging streams of atomized water at an angle,
forwardly and into the fan-driven air stream. Typically, small amounts of compressed
air are injected into the water streams immediately prior to discharge from the atomizing
nozzles, to facilitate the atomizing process. This technique either eliminates or
greatly minimizes the requirement for a compressed air distribution system over the
ski area, but in turn suffers the disadvantage that the equipment is both very expensive,
and inconvenient to operate. Typically, such equipment incorporates a self-contained
internal combustion engine. Thus, each snow making unit requires a substantial capital
investment. Moreover, the equipment is large, heavy and difficult to move easily around
the snow making site. There is an additional inconvenience of having to provide constant
maintenance for the internal combustion engines, as well as constant delivery of fuel,
etc. Thus, although snow making equipment provided with engine-driven fans has certain
significant advantages, it also has important compensating disadvantages. Illustrative
of snow making equipment utilizing self-contained engine-driven fan is US-A-4 083
492.
[0005] In an effort to avoid the inconvenience and investment cost of providing internal
combustion engines with each snow making unit, some of the commercially available
fan-type snow making units have employed electric motors for powering the fan. While
this has certain conveniences in comparison to the use of self-contained internal
combustion engines, it requires the installation and maintenance of heavy-duty electrical
service throughout the ski area, and also presents certain maintenance and safety
problems. Accordingly, notwithstanding the apparent advantages, the use of electrically
driven fans has not proven to be particularly successful commercially. Illustrative
of snow making equipment utilizing electrically driven fans are US-A-3 760 598, US-A-4
004 732, and US-A-4 105 161.
[0006] A further known snow making apparatus of the kind specified in the first paragraph
hereof (US-A-3 945 567) utilizes compressed air from the primary compressed air supply
source to supply motive power to a fan-type snow maker which imposes limitations on
the operation of the system. In this respect, the relationship of air to water in
the atomizing process, for optimum results, is a variable function of temperature
and humidity, particularly temperature. Thus, the utilization of compressed air as
a motive source for the fan tends to impose limitations upon the flow of compressed
air to the system, requiring that the pressurized water serves as the primary variable
on the control of the snow making process. This leads to significant inefficiencies
in the overall operation and importantly limits the capacity of the apparatus to make
snow under marginal conditions.
[0007] It is the object of the present invention to provide a snow making apparatus which
avoids these disadvantages and which operates more efficient and with no important
capacity limitations.
[0008] This object is solved by a snow making apparatus comprising the features of claim
1. A preferred improvement of the invention is subject of claim 2.
[0009] It is one of the significant aspects of the present invention that a novel and improved
high efficiency, fan-type snow making apparatus is provided, which derives motive
power for driving a fan from the high pressure water supply, prior to discharging
of the water through snow making nozzles. This utilization of a turbine powered by
the high pressure water source produces unique and advantageous results in reducing
or eliminating the difficulties associated with the prior snow making equipment listed
above, since a natural water source can be utilized which is available at the locations
where the apparatus is operated.
[0010] The snow making nozzles are of the compressed air-water type, similar in principle
to the conventional snow making guns that do not use fans. In this respect, the compressed
air is introduced into the water supply upstream of the nozzle discharge, enabling
mixing and partial atomization to occur prior to discharge from the nozzle extremity.
The atomized mixture can be discharged directly into the fan-driven stream of distributional
air.
[0011] The use of motive power from the high pressure water supply, advantageously when
combined with the nozzle arrangement, provides for the making and effective widespread
distribution of a high quality snow with outstanding efficiencies in terms of the
consumption of high pressure compressed air from the primary source. Of course, there
is energy utilization from the water supply, but this is more than offset by significant
reductions in the consumption requirements for compressed air, the most expensive
component of the snow making process.
[0012] All of the compressed air-water atomizing nozzles can be placed directly in the fan-induced
air stream, and in particular within the confines of a shroud which surrounds the
fan.
[0013] Thus, the atomized air/water mixture is discharged directly into the distributional
air stream for atomization and snow particle formation. Due to this feature, the constant
bathing of the atomizing nozzles in the distributional air stream serves to keep the
nozzles clean and free of ice accumulation, which can otherwise have a deleterious
effect on the atomizing efficiency and effectiveness of the nozzles.
[0014] For a more complete understanding of the above and other features and advantages
of the invention, reference should be made to the following detailed description of
a preferred embodiment of the invention and to the accompanying drawing.
Fig. 1 is a simplified, side elevational view of a snow making apparatus of the type
incorporating principles of the invention.
Fig. 2 is a front elevational view of the atomizing and discharging unit of the apparatus
of Fig.1.
Fig. 3 is a longitudinal sectional view as taken generally on line 3-3 of Fig. 2.
Fig. 4 is a simplified top plan view of the apparatus of Fig. 1.
Fig. 5 is a simplified schematic flow diagram of the apparatus of the invention.
[0015] Referring now to the drawing, the reference numeral 10 designates generally a support
structure for the snow making equipment, which typically may be a skid suitable for
being towed into position for use, either manually or by the usual snow cat equipment
normally available at commercial ski areas. The support structure 10 advantageously
may include a swivel arrangement 11, for accommodating rotational movement of the
snow generator, generally designated by the numeral 12. A support frame 13 is mounted
on the swivel unit 11 and is adapted for adjustable angular positioning by a pivoted
support 14, enabling the snow generator to be disposed at a desirable angle to the
ground surface.
[0016] Mounted on the frame 13 is a generally cylindrical metal shroud 15 having a downstream
or discharge end 16 and an upstream or intake end 17. Desirably, the intake end is
provided with an outwardly flared collar 18 to accommodate a relatively efficient
flow of air through the shroud.
[0017] Internally the shroud is a support tube 19, which is positioned concentrically within
the shroud by means of a plurality of radial fins 20. The support tube 19 has a bearing
platform 21 mounted rigidly within, to which are bolted a pair of spaced bearing blocks
22, 23. The bearing blocks journal a shaft 24 which carries, positioned just within
the upstream end of the shroud 15 and axial fan 25. In the illustrated structure,
the shaft 24 carries at its upstream extremity a pulley 26, which is driven from a
turbine motor 27 via the output shaft 28 of the latter, a drive pulley 29 and a flexible
belt 30.
[0018] In a practical embodiment of the invention, an axial fan may be a 30,5 cm Vaneaxial
fan, as manufactured by Hartzell Propeller Fan Co., Pi- qua, Ohio, designed to move
approximately 68 m
3/min of air at approximately 3500 rpm, with a power input of approximately one horsepower.
[0019] This level of power is easily derived from a multistage turbine 27 having a water
flow- through approximately 125 I per minute at a pressure drop of approximately 10
kg/cm
2. In a prototype unit the turbine 27 was a Gould multistage pump, modified slightly
for operation as a turbine motor. Desirably, all of the water flow to the snow generator
is supplied through a line 31 leading to the intake of the turbine 27. The use of
the water turbine 27 has proven most advantageous in the efficient production of man-made
_snow. The discharge outlet 32 of the turbine is connected to a circular manifold
33, mounted at the back of the shroud 15 and connected, in a manner to be described,
to a plurality of water atomizing nozzles.
[0020] In the illustrated form of the snow generator, there are shown a series of nine (for
example) atomizing nozzles 34, arranged in a generally circular array, at the forward
end of the shroud 15, and, in this illustratedform of the invention, slightly inside
the inner wall of the shroud. To this end, discharge lines 35 for the outgoing air/water
mixture may pass through the wall of the shroud, near the discharge end thereof. In
this particular form of the invention, the discharge nozzles may be located totally
within the confines of the shroud, or slightly in front of the end thereof, as shown
in Fig. 3, for example.
[0021] To advantage, the water atomizing arrangements comprise an elongated mixing tube
36 for each discharge nozzle, which may be mounted along the outside of the shroud
15, extending axially forward from the water manifold 33. Each mixing tube is of relatively
large diameter (e.g., 38 mm or 1.5 inches) than the discharge line leading therefrom
and is connected at its upstream end to the water manifold 33 through a short delivery
tube 37 provided with a restricted orifice. Also entering the upstream end of the
mixing tube 36 is an air nozzle 38 carrying compressed air and discharging through
a nozzle or orifice 39. Within the mixing tube, there is highly turbulent mixing of
the water and compressed air which then exits the mixing tube through the outlet tube
35 leading to the discharge nozzle 34. Typically and desirably, the discharge nozzle
34 is provided with a plurality (e.g., seven) of discharge orifices, from which issue
a plurality of streams of air mixed with highly atomized water particles, expelled
at relatively high velocity by the compressed air.
[0022] In a typical ski area installation with snow making facilities, valved water and
air supplies 40, 41 (Fig. 5) are provided adjacent the snow making areas, arranged
with quick detachable couplings 42, 43 for connection to the snow making apparatus.
In a typical operational system, the water inlet system of the snow maker may include
an inlet pressure gauge 44, a flow meter 45, a throttling valve 46, turbine inlet
pressure gauge 47 and outlet pressure gauge 48. Downstream of the turbine 27, the
water supply divides and enters the manifold 33 from opposite ends, for maximum uniformity
of water distribution to the several nozzles. As reflected in the schematic of Fig.
5, all of the incoming water supply is, in the illustrated apparatus, directed through
the turbine 27.
[0023] The compressed air system of the snow making apparatus includes an incoming pressure
gauge 49, flow meter 50, throttling valve 51 and manifold pressure gauge 52 on the
downstream side of the throttling valve. The air manifold 53, which may be a circular
manifold similar to the water manifold 33, is arranged to distribute the incoming
compressed air uniformly to the several air injector nozzles 38.
[0024] In typical operation of the illustrated embodiment of the novel system, approximately
125 I per minute of water was delivered to the inlet of the turbine 27 at a pressure
on the order of 17,5 kg/ cm
2. In this prototype unit, approximately 10 kg/ cm
2 was dropped through the turbine to drive the fan at around 3200 rpm. The discharge
water, at a pressure on the order of 7 kg/cm
2, was then directed to the water manifold and discharged into the mixing chambers
36, from which the air/ atomized water mixture is discharged from the nozzles 34.
In the illustrated form of the invention, the mixture is discharged directly into
the distributional stream of ambient air.
[0025] As is well known and recognized, the percentage of compressed air required to be
mixed with water in the snow making process is highly variable, as a function of both
the temperature and humidity. The higher the temperature and/or relative humidity,
the greater proportions of air are required to form ice crystals from the water particles.
In all cases, however, the amounts of compressed air per unit of water required with
the apparatus of the invention are significantly lower than with conventional air/water
atomizing guns under corresponding conditions. For example, under relatively favorable
snow making conditions, it is possible, with the illustrated embodiment of the apparatus
of the invention, to produce large quantities of quality snow utilizing as little
as 2,5 m
3/min of air to approximately 125 I per minute of water, an extremely favorable ratio.
Under extremely unfavorable snow making conditions, approximately 5 m
3/min of air is used with approximately 125 per minute of water. Compressed air is
supplied to the generator at pressures in the range of 6 to 7,7 kg/cm
2.
[0026] Desirably, some of the output of the turbine unit 27 may be utilized for other functions,
such as driving a small alternator 55. The output of the alternator may be utilized
to provide for electrical control functions and/orto effect oscillation of the snow
generator for wider distribution of the snow over the area to be covered. In this
respect, it is anticipated that a high efficiency turbine unit may readily derive
approximately one horsepower via a pressure drop of less than 7 kg/cm
2 at 125 1 per minute, such that the system can easily accommodate the extraction of
minor amounts of energy to service an alternator 55.
[0027] One of the advantageous aspects of the system of the invention is that it enables
the production of snow to be maximized under all conditions. In this respect, one
feature of the illustrated embodiment of the present invention is that the flow of
water to, and its discharge from, the snow generator may be maximized at a constant
value, and the primary variable in the process is the amount of air supplied. This,
of course, is adjusted to a level as low as the ambient conditions will permit. This
feature, which exists in the particular illustrated embodiment, is most advantageous
when these particular ambient conditions exist. In general, the volumes of compressed
air required to be supplied are significantly less than would have to be supplied
to a conventional air/water gun of similar capacity.
[0028] In the illustrated embodiment, the arrangement of the atomizing nozzles directly
within the distributional air stream issuing from the fan 25 also serves to increase
the overall efficient operation of the system. Because the nozzles are continuously
bathed in a relatively high velocity flow of air through the shroud, the nozzles remain
clean and free of ice build up, which can significantly substantially degrade performance
of the nozzles.
[0029] A rather surprising characteristic of the snow generator of the invention is the
fact that it is extremely quiet in operation. Typically, the operation of air/water
snow making guns is accompanied by a great deal of penetrating, annoying noise. In
the operation of the snow generator of the invention, possibly because of the reduced
requirements for compressed air usage, the noise level of the equipment in operation
was sufficiently low as to not be disagreeable and annoying even at locations immediately
adjacent to the discharge nozzles.
1. Maschine zum Erzeugen von Schnee enthaltend eine offene Ummantelung (15), einen
Ventilator (25), um einen Luftstrom durch die Ummantelung (15) zu leiten, sowie eine
Vielzahl von Wassersprühdüsen (34), die am Umfang der Ummantelung (15) angeordnet
und so ausgelegt sind, daß sie das Wasser in den Luftstrom nach vorne sprühen können,
dadurch gekennzeichnet, daß die Düsen (34) Zerstäuberdüsen für Luft und Wasser sind,
die zerstäubtes Wasser und Druckluft abgeben und daß eine mit Wasser betriebene Turbine
(27) den Ventilator (25) antreibt, und der Einlaß der Turbine (27) an eine externe
Druckwasserquelle angeschlossen ist, und daß Abgabemittel (36) vorgesehen sind, um
die Zerstäuberdüsen (34) mit Wasser zu speisen, mit denen die Turbine (27) in Serie
geschaltet ist, sowie Abgabemittel (38) für Druckluft, die oberhalb der Zerstäuberdüsen
(34) an die Wasserabgabe (36) angeschlossen sind, sowie Mittel (50, 51), um die Druckluftflußrate
aus der Abgabevorrichtung im Vergleich zur abgegebenen Wassermenge zu steuern.
2. Maschine nach Anspruch 1, dadurch gekennzeichnet, daß Mittel vorgesehen sind, um
die gesamte Wassermenge, die von den Zerstäuberdüsen (34) für Wasser und Luft ausgestoßen
wird, durch die Antriebsturbine (27) zu leiten.