Note: Descriptions are shown in the official language in which they were submitted.
2082149
This invention relates to a snowmaking gun, i.e. a
gun for producing artificial snow.
In general, the basic process for producing
artificial snow (involving the formation of ice crystals) is a
heat exchange process involving heat rejection. When
- sufficient heat has been removed under proper temperature
conditions, small droplets of water will freeze. There are
;~ four major factors affecting the removal of heat from water
droplets, namely:
!`, 10 (1) the flight time of the droplets,
(2) the temperature differential between the
ambient air and the water droplets,
~, :
- (3) the relative humidity of the air and the
~; ..
barometric pressure, and
(4) the diameter and surface area of the droplets. -
~ ,
The basic types of snowmaking apparatuses in use
`; today include the so-called compressed air type and the fan
type. In a compressed air apparatus, air and water are
~` supplied to snow guns for atomizing, projection and
j
- 20 distribution of an air/water mixture. A fan type apparatus
! includes a large tubular casing containing a fan for producing
~;~ a large volume of air. Water is atomized hydraulically and
. . .
~- injected into the air stream produced by the fan. Direct
,- nucleation is required with this type of apparatus. All
:~; "
snowmaking apparatuses must achieve the same objectives,
namely the atomizing of water droplets, the projection of the
.
'-,~':
~;
-`` 208?,14~
droplets into air so that they can freeze, and the nucleation
of water droplets to enhance freezing in the minimum time at
the highest possible temperature. Moreover, it is desirable
to achieve the foregoing as economically as possible.
In the vast majority of compressed air type
apparatuses, air and water are mixed prior to being discharged
from a nozzle as a mixture. The compressed air facilitates
internal mixing and nucleation. The high velocity of the
.~ .
; mixture results in freezing of smaller droplets to create
i` 10 nuclei. The compressed air also provides most of the force
necessary to pro]ect the droplets into the air. The secondary
;~ or entrained ambient air provides the largest part of the
cooling required to convert the water droplets into ice
particles.
, .
Both type of apparatus has its advantages and
disadvantages. Compressed air snow guns are lightweight,
,~.
!'':', ~ structurally simple, easy to operate, store and transport,
.. . .
~ relatively problem free on the slopes, more efficient in
i~ marginal temperatures, and better adapted to steep and narrow
.
slopes. However, such guns are noisy, result in high energy
-; consumption and costs, and experience higher water evaporation
-,.
losses. Fan type machines have lower energy consumption and
;~:
` costs, higher snowmaking capabilities, lower noise level and
``~ less water evaporation than compressed air/water guns.
. .
-~ 25 Unfortunately, fan type machines are large and heavy,
difficult to use on steep slopes, and are more complicated to
.;, ~
' ~
,,. : .
~: ~
2~2140
operate, requiring better skills than the compressed air/water
gun.
Comparison of a fan type machine (see U.S. Patent
No. 4,711,395, which issued to the present inventor on
December 8, 1987 with the best compressed air guns resulted in
the conclusion that the fan type machine converts water into
snow while using less than one fifth the energy required by
the best air/water guns operating at peak efficiency.
As a general principle, the quantity of snow
produced is directly proportional to the quantity of water
employed. ~owever, at any given temperature and humidity~ and
for a specific volume of air, only limited quantities of water
may be sprayed into the air and result in high quality, dry
snow. Thus, for any snowmaking machine, there is a trade off
between snow quantity and quality which vary in accordance
with climate conditions. As mentioned above, the production
of artificial snow is a heat exchange process in which the
actual heat exchange occurs at a distance from the apparatus
- or gun. ThuS, a relatively important part of the system is
the plume of air and water interacting with ambient air
outside of the apparatus. In order to ensure efficient
snowmaking, it is important to ensure that (1) proper mixing
of water droplets and air occurs in the plume outside the
i~ machine, (2) the water droplets remain airborne for a
- 25 sufficient period of time to become frozen, and (3) energy -
consumption be kept to a minimum.
''
20821~0
,
Recently, there has been a great deal of activity in
the area of artificia~ snowmaking. In general, the effort
.~
has been concentrated in the area of mixing within the
machine, i.e. of creating a mixture of air and water within
the gun. Very little effort has been addressed to increasing -
the interaction of air and water in the plume itself which is
~,
acknowledged to be most important area in the heat exchange
process.
For a given nozzle, the degree of atomization is a
` 10 function of the supply pressure of the fluids, and the mass
ratio of the air and water. Existing compressed air guns rely
,
; on the production of homogeneous mixture in the guns. With
,.
such guns, the air and water must be introduced at
.~
approximately the same pressure (70 to 150 psi). Once a
`~ 15 discharge orifice size has been chosen, the operating
"~
conditions and characteristics with respect to available
- ~ air/water ratios for given fluid pressures are established.
Moreover, the use of fixed orifices for air and water means
that water can be adjusted only by varying the water pressure.
At marginal temperatures, guns operate with minimum water
flow, i.e. minimum water pressure. In such circumstances,
when it is most needed, the full potential momentum energy of
the pressurized water supply is not utilized.
The object of the present invention is to provide a
~ 25 snowmaking gun of the compressed air/water type which
"-~ maintains the advantages of small size, weight and portability
` 2~821~
- while adding positive features normally associated with fan
: type machines, namely low energy consumption and high
snowmaking capabilities.
Accordingly, the present invention relates to a
snowmaking gun comprising:
(a) casing means including
~:; (i) outer shell means,
` (ii) inner shell means defining an air chamber and
an annular air discharge slot with said outer
; 10 shell means;
(b) tube means extending substantially entirely
through said inner shell means for receiving water
` from a source of water under pressure and for
discharging the water from the gun; and
(c) valve means at the outlet end of said tube
means for controlling the volume of water flowing
through said tube means, and shaping the water into
: an annular stream of small droplets for discharge
. into the center of the annular stream of air
--: 20 exiting said air discharge slot for mixing with said
stream of air downstream of the discharge end of the
i~ gun for producing snow, temperature permitting.
: The invention will be described in greater detail
with reference to the accompanying drawings, which illustrate
25 a preferred embodiment of the invention, and wherein: .
.,` ~
. 5
''~
`,
g ~
- Figure 1 is a side elevational view of a snowmaking gun in accordance with the present invention;
Figure 2 is a longitudinal sectional view of the gun
` ~:
of Fig. 1.
~- 5 Figure 3 is an exploded, partly sectioned, side
elevational view of a coupler, guide rod and a water tube used
in the gun of Figs. 1 and 3;
,. .
f~' Figure 4 is a side view of the coupler of Fig. 3;
6 Figure 5 is an end view of the coupler of Fig. 4 as
;, 10 viewed from the right;
Figure 6 is a perspective view of the guide rod of
Fig. 3 on a larger scale;
Figure 7 is an exploded, partly sectioned side
. .
elevational view of a nozzle body, a pattern control sleeve
` 15 and a turbine used in the gun of Figs. 1 and 2;
;:
- Figure 8 is a perspective view of a control ring -
used on the nozzle body of Fig. 7;
Figure 9 is a perspective view of a cam used in the
nozzle body of Fig. 7;
Figures 10 and 11 are schematic partly sectioned -~
side views of the discharge end oE the pattern control sleeve
! of Fig. 7;
:" ~
'~ Figure 12 is a perspective view of a threaded insert
,
and clip used in the nozzle body and pattern control sleeve of
Fig. 7;
: :
'~' Figure 13 is an end view of the turbine of Fig. 7;
6 ~ -
: ~ ~
~ . ~
~ ~1
2082~4~
- Figure 14 is an exploded side view of inner and
- outer shells used in the gun of Figs. 1 and 2; and
Figure 15, which appears on the second last sheet of
drawings, is a partly sectioned side view of the shells of
Fig. 14 in the assembled condition.
t should be noted that Figs. 3, 7 and 14 placed
end-to-end with their centerlines aligned illustrate the
` complete apparatus in the disassembled condition.
Referring to Figs. 1 and 2 of the drawings, the main
elements of the snowmaking gun include a coupler 1, a water
tube 2, a guide rod 3, a valve body 4, a nozzle body 5, a
water pattern control sleeve 6, a plastic turbine 7, an inner
shell 8 and an outer shell 9.
As best shown in Figs. 2 to 5, the coupler 1 is
defined by a tubular body 10 with an internally threaded
inlet end 11 for receiving an adapter 12 and a pipe 13, which
connects the gun to a source of water under pressure (not
shown). An annular groove 14 in the inlet end 11 of the
coupler 1 receives a rubber seal 15. The coupler 1 is
, .
~ 20 connected to one end of the nozzle body 5 (Fig. 7) by a -
i
plurality of ball bearings 17 (forty in this case) which are
,~ i
- inserted through an opening 18 into complementary, opposed,
. .
annular grooves 19 and 20 in the coupler 1 and the nozzle
.: ~
body, and a set screw 22. If the screw 22 is not tightened
-` 25 against the body 5, the latter can rotate. However, for
normal use, the screw 22 is tightened to lock the two elements
.,
:,
,
,'
: .
~ `:
20~2l~a
together. An O-ring 23 is sandwiched between a shoulder 24 in
the coupler 1 and the bevelled inlet end 25 of the nozzle
- body 5.
A pair of diametrically opposed, concave grooves 27
(Figs. 3 and 5) are provided in the coupler 1 for receiving a
pair of lugs 28 on the inlet end of the guide rod 3 which
prevents rotation of the rod in the gun. Shoulders 30 on one
side of the lugs 28 bear against the inlet end 25 of the
nozzle body 5 when the gun is assembled (Fig. 2). The
elongated body 31 of the rod 3 extends through most of the
length of the tube 2 stopping short of the internally flaring
discharge end 33 thereof. A conical tip 35 on the inlet end
: ,
of the rod smoothly diverts the flow of water along the length
of the rod. The rod 3 is centered in the tube 2 by four vanes ~
36 near the downstream end of the rod in the direction of ; ;
water flow. The vanes 36 are spaced equidistant apart around
the rod 3.
As best shown in Fig. 2, the tube 2 is slidably
sealed in the body 5 and the water pattern control sleeve 6 by
, 20 a pair of O-rings 38 and 39, respectively. It will be noted
.,,
that the tube 2 extends beyond the downstream end of the body
5, the larger diameter discharge end 33 thereof slidably
engaging the discharge end 40 of the sleeve 6. The volume of
` water discharged from the tube 2 is controlled by a valve,
- 25 which includes a valve body defined by a disc 4. The disc 4 ;
(Fig. 3), which may have a bevelled trailing edge 42 tFig. 2)
~` 8
`~ 2~21~0
- is connected to the downstream end 43 (Fig. 6) of the rod 3
by a screw 45. Shims 46 (Fig. 3) are provided in an annular
recess 47 in the end of the 4. By moving the tube 2
longitudinally on the rod 2, the opening between the disc 4
and the tube 2 can be varied to control the volume of water
discharged from the tube.
Longitudinal movement of the tube 2 is effected
using the nozzle body 5, a cam 49 (Figs. 7 and 9) and a
control ring 50 which includes an annular flange 51. A pin 52
extends through one side of the body 5 into a short
- longitudinally extending recess 53 (Fig. 3) in the tube 2,
permitting longitudinal movement of the tube while preventing
rotation thereof in the body 5. The cam 49 is slidably
mounted in a semicircular slot 54 in the body 5.
. :
~ 15 Referring to Fig. 9, the cam 49 includes an arcuate
, body 5~ conforming in curvature to the side wall of the body
5. Flanges 56 extend outwardly from the sides of the body 55
~ for sliding on the body 5 when the body 55 of the cam 49 is
,~ inserted into the slot 54. A generally oval lug 57 on the
. .
: 20 inner surface of the body is inclined or angled with respect
-
to the longitudinal axes of the cam body 55 and the slot 54.
When the gun is assembled, the lug 57 extends into a short
! ,:
:; inclined groove 58 (Figs. 2 and 3) in the side of the tube 2.
Thus, because the tube 2 cannot rotate in the body 5, rotation
of the cam 49, i.e. movement of the cam in the slot 54 causes
;'
:`
20~21~
longitudinal movement of the tube 2 in the body 5 to adjust
the valve opening.
Rotation of the cam 49 is effected using the ring
50, which is best shown in Fig. 8. The annular external
flange 51 cf the ring 50 bears against an annular flange 59
on the noæzle body 5 for maintaining the ring 50 in contact
with the cam 49. A recess 60 in the interior of the ring 50
engages the outer portion of the cam 49 (exterior to the body
5) for moving the cam longitudinally in the slot 55. A rod-
shaped handle 61 is used to rotate the ring 50. The threaded
end 62 of the handle extends into the ring 50 for slidably
receiving the latter on the body 5.
The pattern control sleeve 6 is mounted on the
- nozzle body 5. The position of the sleeve 6 on the body 5 can
.
be adjusted to change the pattern of the water discharged from
the gun. The water pattern can be more or less cylindrical
(Fig. 10) or diverging (Fig. 11) depending upon the location -~
of the sleeve 6 in relation to the tube 2. Teh pattern is ;
adjusted by moving the sleeve 6 relative to the fixed nozzle -~
body 5.
The control pattern sleeve 6 includes a cylindrical,
,, ~ .
, tubular body 63 with a wide, annular flange 64 at the inlet
end thereof and a narrow annular flange 65 near the discharge
end thereof. A semicircular slot 66 is provided in the body
. ~ .
63 immediately downstream of the flange 64 for receiving a
semicircular, internally threaded insert 67. The insert 67
`: :
,':' 10 ';,
. ~
.
..~,.
.
,
20821~
~ includes a section 68 of thread on the interior thereof for
engaging a helical groove 69 in the nozzle body 5. Thus,
the nozzle body 5 is placed in the sleeve 6, and the insert 67
is placed in the slot 66. The insert 67 is held in position
by a retaining band or clip 70, the hooked ends 72 of which
engage notches 73 in the insert 67. When the sleeve 6 and all
external parts attached thereto, including the inner and outer
shells 8 and 9, respectively, are moved as a unit (rotated on
the fixed nozzle body 5) beyond the outlet end of the tube 2,
the water pattern becomes more divergent (Fig. 11) and when
moved in the other direction to a position in which the
discharge end 33 of the tube 2 is inside the sleeve 6 (Figs. 2
and 10), the water pattern becomes more cylindrical. Water
discharged from the tube 2 impinges upon the sleeve 6, and
instead of flaring is discharged in a more or less
cylindrical tube from the sleeve 6. In order to facilitate
understanding, the movement shown in the schematic drawings
(Figs. 10 and 11) is somewhat exaggerated.
The flange 65 includes a concave, annular groove for
receiving an O-ring 75. Shoulders 76 are provided on the
^ trailing end of the sleeve 6 for rotatably supporting the
plastic turbine 7 on the sleeve. The turbine 7 is defined by
a ring 77 with generally L-shaped blades 78 extending
; outwardly therefrom. The outer ends of the blades 78 are
~-~ 25 triangular in cross section with bevelled outer edges. The
- turbine 7 is used to atomize the water discharged from the
11
~,'.
20~2~0
. ~:
tube 2. The water striking the blades 78 causes the turbine
-:
to rotate rapidly, and consequently the blades chop the water ~-
into the fine droplets required to make snow. The turbine 7
is retained in position by the shoulder 79 of a retainer ring ~;
80. Screws 82 pass through diametrically opposed holes 83 in
the ring 80 into the flange 65 of the sleeve 6. An O-ring 84 ~
seals the ring 80 in the inner shell 8. -
The sleeve 6 is surrounded by the inner shell 8,
.
, which is held thereon by radially extending set screws 86
(Fig. 14) which engage the flange 64. An O-ring 87 provides a
.~., ,
seal between the upstream end of the shell 8 and the sleeve 6.
~ An annular flange 89 on the upstream end of the inner shell 8
'~ receives screws 90 and 91 (Figs. 1, 2 and 15~ for retaining -~
the cylindrical outer shell 9 on the inner shell 8, and for
adjusting the position of the outer shell on such inner shell,
respectively. For such purpose, the screws 91 are jack
~ screws. By loosening the screws 90, the screws 91 can be
,, rotated to change the spacing between the flange 8 and the
~ downstream end 93 of the outer shell 9. By again tightening ~ ;
!, 20 the screws 90 the outer shell 9 is fixedly connected to the
;~ inner shell 8.
,........................................................................... .
`~ The cylindrical body 95 of the inner shell 8 and the
~ recessed interior of the body 96 of the outer shell 9 define
x an air chamber 97 (Figs. 2 and 15) for receiving air from a
i 25 source of compressed air (not shown) via a hose 99 and an
"~ inlet coupier 100 (Figs. 1 and 14). Air is discharged from
.
i 12
, .
',`
''-,
20~2~.~0
the chamber 97 via an annular slot 102, which is followed by a
flaring mouth 103, whereby the air is caused to flare
outwardly during discharge from the gun, i.2. to follow the
surface of the flaring mouth 103. An annular groove 105
defining a resonator cavity is provided adjacent the outlet
end 106 of the body 96. As indicated by the broken lines 108
^~ in Fig. 14, the outer shell 9 can end immediately downstream
of the discharge passage 102.
` When using the above described gun, the water and
air are discharged separately from the gun for mixing
downstream of the gun. There are two parameters which have
. been given special consideration, namely the power of the
water jet or stream, and the power of the compressed air jet
or stream. Whereas higher pressures result in better reach
...~.
. 15 (or throw) for water, air is much lighter than water and its
` reach at, e.g. 100 psi is minimal compared to water at the
` same pressure. It occurred to the present inventor that it is
-~ not a good approach to mix air and water internally prior to
discharge as a mixture as is being done with existing guns.
`;; 20 The friction losses are much smaller when the air and water
,"
are discharged separately from the gun. With a fixed orifice
si7e using an internal mix gun, as water flow increases air
~- flow decreases. This characteristic has the undesirable
result of larger droplets of water at higher flow rates.
. ~ .
~ 25 By maintaining the fluids separate until discharge
;',`
the maximum momentum energy of the water is efficiently
v~ 13
~i'..
.
` 2~2140
utilized to achieve better reach and atomization, i.e.
increased snowmaking capacity. Optimum air flow exit velocity
is achieved to improve nucleation due to refrigerating
- properties of the expanding air at higher velocities. A low
constant airflow volume (approximately 200 cfm) compared to
the high variable flow of existing guns results in less noise.
Thile the use of a turbine 7 is preferred, because water
passing through the valve is atomized, the turbine can be
~ : '
omitted. The use of the spinning teeth 7 turbine results in a
wide annular water curtain. The self-carrying properties of
` the water results in reduced energy consumption compared to
the use of a homogeneous mixture, especially when water
!.~ pressures can be higher than air pressure.
The annular air stream expands and its velocity is
reduced to that of the water stream. The air stream acts as a
water droplet carrier for the first droplets exiting the plume
to reduce the dribbling effect. Such first droplets are
finely atomized and carried away by the high peripheral air
., .
~- velocity. The use of a flaring mouth 103 in the gun shapes
the annular air stream and provides a base for an annular
resonator cavity 105. The use of an annular resonator cavity
., .
105 creates a sonic field at the mouth of the gun. Resonant
vibrations developing in the cavity are transmitted through
the air stream into the wide annular water curtain. The
resonant vibrations enhance water atomization already
- occurring downstream of the water discharge valve (disc 4),
~':
14
.
;':
-` 2082~a
but with much less energy than required by direct contact of
compressed air with water (or a mixture of compressed air and
water). The high frequency waves produced by the resonator
-; cavity 105 result in a chopping effect which breaks the liquid
` 5 stream into extremely small droplets.
-; The use of the gun permits the use of a constant air
supply independently of ambient air temperature. The energy
supply is constant as is the case with fan type machines.
Water volume is controlled using a valve in the gun rather
than by making water pressure adjustments (as is done in
existing guns). Thus high water pressure can be maintained at
.-,
marginal temperatures when the pressure is required to produce
good quality snow.
Finally, the energy requirements of the gun of the
` 15 present invention are only slightly higher than those for fan
type machines, and are substantially lower than those for the
~ best performing existing compressed air guns.
.,~
~ ' .
., .
,i:
~ ` ' , I
~, .
~ .
.
, !',
, .
~! 15
.~
..
~; :
~:,
,'
~., .
