GB2248921A

GB2248921A - Snow making

Info

Publication number: GB2248921A
Application number: GB9120572A
Authority: GB
Inventors: Malcolm George Clulow; David Frederick Winnett
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-09-28
Filing date: 1991-09-27
Publication date: 1992-04-22
Anticipated expiration: 2011-09-27
Also published as: GB2248921B; GB9120572D0; GB9021219D0

Abstract

Snow making apparatus comprises a nucleating means (12) supplied with high pressure cold fan air (13, 14) and directed into the inlet end (16) of a venturi (11). Bulk water supply means (18, 19) are provided towards the outlet end (17) of the venturi and low pressure air is entrained from the cold ambient air (15) at the inlet end due to the action of the venturi (11). The nucleating means comprises a relatively warm water jacket (22). Part of this water is atomised at jets (28) by compressed air fed into the nucleating means (12) at inlet (27). Water and air issuing from the supply means (18, 19) freezes onto the frozen nuclei which issue from jets (28) to form snow flakes. <IMAGE>

Description

Title: SNOW MAKING This invention relates to an apparatus and to a method of snow making. It was devised particularly for use indoors for making real snow artificially but it may also be used under certain circumstances in an outdoor environment.

Prior snow making machines have involved the use of high pressure air jets into which bulk water is injected, arrangements being made for nucleation to cause crystallization of the water.

Such apparatus is described in for example European Patent Application 82407535 Tropeano and US Patent No. 4214700 VanderKelan. Tropeano provides a high velocity plume of snow using large volumes of compressed air and high pressure water, the plume entraining surrounding air by induction. However, such an apparatus involving large volume air entrainment tends to form a microclimate within the plume which has psychrometric properties very different from those of the surrounding air.

VanderKelan describes a fan assisted apparatus using a large axial flow fan to produce the velocity for a snow plume derived from separate nucleating and bulk water nozzles. The plume microclimate is to some extent diluted by the fan but, even so, a further volume of air needs to be entrained in the plume in operation.

These and other previously available snow making apparatus have certain disadvantages, including:1. High noise levels, 2. Poor snow quality (ice spheres instead of smaller snow crystals), 3. High energy requirements, 4. Physical size and output too large for practical indoor use, 5. Psychrometrically inefficient due to wide spectrum of particle sizes causing high humidities and the need for large air handler volumes indoors, 6. Poor controllability.

It is an object of the present invention to provide a method and an apparatus for snow making which overcome or reduce some or all of the above disadvantages.

Viewed from a first aspect, the invention provides snow making apparatus comprising nucleating means; bulk water supply means; a venturi having said nucleating means at or adjacent its input end and said bulk water supply means at or adjacent its output end; and primary air supply means arranged to supply low volumes of high pressure, low temperature air, to said venturi at or adjacent said nucleating means additional low temperature air being entrained from the ambient air by the flow of primary air through said venturi.

The nucleating means may be supplied with low pressure air and with water at a temperature above freezing point. The nucleating means may comprise ultrasonic nucleating means.

The bulk water supply means may be supplied with low pressure air and with water at above freezing point. A plurality of bulk water supply means may be provided spaced along said venturi.

Freeze protection for example a circulating water jacket may be provided for the nucleating means and the bulk water supply means.

Preferably, the water supply to the nucleating means and/or the bulk water supply means may be provided by part of the water supplied to the circulating water jacket, the quantity passing into the nucleating means and/or bulk water supply means being controlled by valve means for example a solenoid valve. This may be electronically controlled by a computer.

Viewed from a further aspect, the invention provides a method of snow making comprising the steps of supplying low pressure compressed air and water at a temperature above freezing point to a nucleating means; supplying high pressure primary air at a low temperature to a venturi having said nucleating means at its input end; and supplying low pressure compressed air and water at a temperature above freezing point to bulk water supply means disposed within said venturi at or adjacent its output end, whereby additional low temperature air is entrained from the ambient air by the flow of primary air through said venturi.

An embodiment of the invention will now be described in more detail by way of example only with reference to the accompanying drawings in which Figure 1 is a diagrammatic sectional view through a snow making apparatus, Figure 2 is an end view of the apparatus shown in Figure 1, Figure 3 is a sectional view of a nucleating means, Figure 4 is a front elevational view of the nucleating means of Figure 3, Figure 5 is a rear elevational view of the nucleating means of Figure 3, Figure 6 is a sectional view of a bulk water supply means.

Referring firstly to Figure 1 of the drawings, a snow making apparatus generally indicated at 10 comprises a venturi 11 having, at its inlet end, a nucleating means 12 shown in more detail in Figure 3-5 of the drawings. The nucleating means 12 has a central opening supplied with high pressure fan air through a hose 13 from a fan 14. On passing through the nucleating means, the high pressure fan air 13 entrains further air indicated by the arrows 15 which is entrained from the atmosphere. It will be appreciated that, for snow making to take place, this ambient air must be at a temperature below freezing point. The air supplied by the fan 14 is also at a temperature below freezing point.

Thus, at the inlet end 16 of the venturi, high pressure air from the fan 14 entrains ambient air 15 in relatively larger quantities at a ratio between 1:1 to 1:50, and the air is passed through and around the nucleating assembly 12 to be described.

Towards the outlet end 17 of the venturi, one or more bulk water supply means 18, 19 is or are provided. In the example illustrated, two sets of bulk water supply means are provided, one at a position spaced slightly from the centre of the venturi towards the outlet end 17 and the other, 19, very close to the outlet end 17.

The arrangement is such that very small nucleating ice particles are generated by the nucleating means 12 and injected into the air flow of the inlet of the venturi. Further water and air issuing from the bulk water supply means in relatively larger quantities, freezes onto these ice nuclei to form snow flakes which issue from the outlet end 17 of the venturi.

The entire apparatus is mounted on a traversing means 20 such as a trolley or swing arm so that the plume of snow generally indicated at 21 which issues from the outlet end can be traversed to provide for example an indoor ski slope.

Having described the apparatus in general terms, reference will now be made to Figures 3-5 of the drawings, showing the nucleating means.

The nucleating means generally indicated at 12 comprises a disclike cylindrical body having an outer water jacket 22 which is supplied with low pressure water at a temperature above freezing point. Part of this water is admitted to the nucleating means to form ice nuclei by a solenoid valve 23 which may be electronically controlled for example by a computer. The bulk of the water is merely re-circulated through the water jacket 22 and, since it is supplied at a temperature of between +1 and +20 degrees centigrade, it acts to ensure that the nucleating assembly does not freeze up in use. The water to the nucleating means 12 is supplied in quantities of between 1 and 10 litres per second at a pressure of between 1 and 10 times atmospheric, through the water inlet 24.

If desired, an anti-freeze heater 25 may additionally be provided to ensure that the nucleating assembly does not freeze during the period when the gun is not in use.

Excess water returns to a storage means through the water outlet 26. Compressed air is fed into the nucleating means at 27, this compressed air also being at a temperature above freezing point, typically between +5 and It15" centigrade. A quantity of between 0.1 and 1 cubic metre per second is used, at a relatively low pressure of between 2 and 7 times atmospheric.

The nucleating means 12 is operated ultrasonically and provides a fine mist of water particles which instantly freeze in the low temperature air supplied by the fan 14 and entrained at 15 through the venturi. These frozen particles issue from the atomising jets 28 of the nucleating means.

The arrangement of the bulk water supply means is somewhat similar to that of the nucleating means as can be seen from Figure 6 of the drawings. However, in this case, the water is supplied in relatively larger quantities, typically 0.5 to 10 litres per second at a pressure of between 2.5 and 10 times atmospheric. This water is also supplied at a temperature of between +1 and +20 centigrade and again a water jacket is provided to ensure that the bulk water supply means do not freeze in use. The bulk water is arranged to issue in particles of between 5 and 150 microns in size, compared to the smaller nuclei of 10 to 70 microns formed by the nucleating means 12. These particles build up on the nuclei and agglomerate into snow flakes which appear in the plume 21 issuing from the venturi.Again, the bulk water supply means 18 has a low pressure compressed air inlet, indicated at 29, through which air at between +5 and +15 centigrade is supplied at between 2 and 7 times atmospheric pressure in a quantity of between 0.5 and 1 cubic metres per second. The water jacket 30 is supplied with bulk water as referred to at 31, part of this water being used to make snow by being injected at the suitable particle size of 50 to 150 microns through the jets 32 under the control of a further solenoid valve 33. The remainder of the water 30 forms a circulating water jacket as before.

The apparatus differs from prior proposals for snow making particularly in that the venturi is used to entrain large quantities of ambient air which pass directly over the nucleating means for very efficient formation of nuclei. Further crystal growth is then promoted by the addition of bulk water, also during the course of passage of the air through the venturi, resulting in a more homogeneous snow plume issuing from the end of the venturi.

The present invention does not require the use of large amounts of compressed air whether supplied by fan or otherwise and also does not require the use of high pressure water to achieve atomization of the water. In order to produce a controlled growth of snow flakes, several sets of bulk water supply means may be provided, allowing for different sizes of water droplets to be used to control the flake size and secondary crystal growth. Automatic control of the quantities of air and water may be arranged by programmable means such as a computer. This enables good control of the size and volume of the snow plume to be achieved.

Claims

1. Snow making apparatus comprising nucleating means; bulk water supply means; a venturi having said nucleating means at or adjacent its input end and said bulk water supply means adjacent its output end; and primary air supply means arranged to supply low volumes of high pressure, low temperature air to said venturi at or adjacent said nucleating means, additional low temperature air being entrained from the ambient air by the flow of primary air through said venturi.

2. Apparatus according to claim 1 wherein the nucleating means are supplied with low pressure air and with water at a temperature above freezing point.

3. Apparatus according to claim 2 wherein the nucleating means comprise ultrasonic nucleating means.

4. Apparatus according to any preceding claim wherein the bulk water supply means are supplied with low pressure air and with water at a temperature above freezing point.

5. Apparatus according to any preceding claim wherein a plurality of bulk water supply means are provided spaced along said venturi.

6. Apparatus according to any preceding claim including freeze protection for the nucleating means.

7. Apparatus according to any one of claims 1-5 wherein freeze protection is provided for the bulk water supply means.

8. Apparatus according to claim 6 or claim 7 wherein freeze protection comprises a circulating water jacket.

9. Apparatus according to claim 8 wherein the water supply to the nucleating means and/or the bulk water supply means are provided by part of the water supplied to the circulating water jacket.

10. Apparatus according to claim 9 wherein the quantity of water from the circulating water jacket passing into the nucleating means and/or bulk water supply means is controlled by valve means.

11. Apparatus according to claim 10 wherein said valve means comprises a solenoid valve.

12. Apparatus according to claim 10 or claim 11 wherein said valve means is electronically controlled by a computer.

13. A method of snow making comprising the steps of supplying low pressure compressed air and water at a temperature above freezing point to a nucleating means; supplying high pressure primary air at a low temperature to a venturi having said nucleating means at its input end; and supplying low pressure compressed air and water at a temperature above freezing point to bulk water supply means disposed within said venturi at or adjacent its output end, whereby additional low temperature air is entrained from the ambient air by the flow of primary air through said venturi.

14. Snow making apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

15. A method of snow making substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.