Abstract
A nucleator nozzle (20) for producing ice nuclei is designed as convergent-divergent nozzle. The nozzle channel (25) has a section (27) that is widening. The ratio of the cross-sectional area of the outlet opening (23) to the cross-sectional area of the nozzle channel (25) in the region of the nucleus diameter (26) is at least approximately 4:1. A snow lance (1) having at least one nucleator nozzle (20) and having at least one water nozzle (30; 30) is designed such that water droplets (32) produced by the water nozzle (30; 30) pass through a droplet path (31; 31) of at least 20 cm until they reach ice nuclei (28) from the nucleator nozzle (20) in a germination zone E.
Claims
1. An arrangement for producing ice nuclei, the arrangement comprising: at least two nucleator nozzles; a common mixing chamber; said common mixing chamber having at least one compressed air inlet opening and at least one water inlet opening through which air and water for an air-water mixture are fed into the common mixing chamber; and said at least two nucleator nozzles each having a nozzle channel and a nozzle outlet opening; wherein the mixing chamber is formed by a tubular part, the at least one compressed air inlet opening being arranged on an end of the tubular part and the at least one water inlet opening being arranged on a lateral side on the tubular part, said common mixing chamber is connected to each of the nozzle channels via a channel junction, a cross section of each of the nozzle channels tapers in a first section in a direction of the outlet opening to a core diameter, the cross section of each of the nozzle channels subsequently expands in a second section in the direction of the outlet opening, and a cross sectional area of the outlet opening to a cross sectional area of the nozzle channel, in a region of the core diameter, is at least 4:1.
2. The arrangement as claimed in claim 1, wherein an angle of the nozzle channel, in an expanding second section between the taper and the outlet opening, is less than 30.
3. The arrangement as claimed in claim 1, wherein each nucleator nozzle is a circular jet nozzle.
4. The arrangement as claimed in claim 1, wherein each nucleator nozzle is a flat jet nozzle.
5. The arrangement as claimed in claim 1, wherein the water inlet opening opens laterally into the mixing chamber.
6. The arrangement as claimed in claim 1, wherein the mixing chamber is configured in such a manner that a dispersed droplet flow is produced at least in a region of a mixing section in the mixing chamber, resulting in atomization in a region of said nucleator nozzle.
7. The arrangement as claimed in claim 6, wherein the cross sectional area in the region of the mixing section is less than 9 times greater than an overall cross sectional area of the outlet openings of the at least two nucleator nozzles.
8. The arrangement as claimed in claim 6, wherein a length of the mixing section is at least 3 times greater than a diameter of mixing chamber in the region of the mixing section.
9. The arrangement as claimed in claim 1, wherein the nucleator nozzles are each made as separate parts.
10. An arrangement as claimed in claim 1, wherein a filter is arranged at least in a region of the at least one water inlet opening for filtering the water being supplied to the at least two nucleator nozzles.
11. The arrangement as claimed in claim 10, wherein the filter is a sleeve-shaped filter element which is composed of a wire fabric or wire lattice and is arranged at a distance around the tubular part.
12. The arrangement as claimed in claim 1, wherein, said arrangement has at least one water supply pipe which runs parallel to the tubular part and is provided with at least one passage bore, and the water is feedable into the at least one water inlet opening via the passage bore.
13. The arrangement as claimed in claim 1, wherein the nucleator nozzles are distributed on a circumference about an axis and are each directed radially away from the axis.
14. The arrangement as claimed in claim 1, wherein the nucleator nozzles are fastened or can be fastened to a head part via a screw connection, the head part has a central channel which runs in a direction of an axis and is divided into supply channels which are directed radially away from the axis and are intended for feeding the respective nucleator nozzles.
15. A snow lance for producing artificial snow comprising an arrangement according to claim 1, the snow lance having at least one water nozzle, wherein an ice nuclei jet can be produced with each of the at least two nucleator nozzles and a droplet jet can be produced with the at least one water nozzle, said jets, after passing through an ice nuclei section and after passing through a droplet section, respectively, meeting in a germination zone, wherein the ice nuclei section is at least 10 cm, and/or in that the droplet section is at least 20 cm.
16. The snow lance as claimed in claim 15, wherein the snow lance has a lance body with a substantially cylindrical shape.
17. The snow lance as claimed in claim 16, wherein at least one of the at least two nucleator nozzles is arranged at an angle of 0 to 45 to a plane perpendicular to an axis of the lance body in such a manner that the outlet opening is directed radially or obliquely upwardly away from the lance body.
18. The snow lance as claimed in claim 17, wherein the at least one water nozzle is arranged at an angle to a plane perpendicular to the axis of the lance body and is directed toward the at least one nucleator nozzle.
19. The snow lance as claimed in claim 16, wherein the at least two nucleator nozzles are distributed around the circumference of the lance body.
20. The snow lance as claimed in claim 16, wherein the lance body is provided with at least two groups of water nozzles which are arranged in at least two different axial positions on the lance body, and one of said two groups comprises the at least one water nozzle.
21. The snow lance as claimed in claim 20, wherein all of the water nozzles of the at least two groups of water nozzles are oriented in such a manner that the droplet jets produced by the water nozzles strike against the ice nuclei jet only after passing through a droplet section of at least 20 cm.
22. The snow lance as claimed in claim 20, wherein the at least two groups of water nozzles are charged individually with water.
23. The snow lance as claimed in claim 15, wherein at least one water nozzle is arranged below the at least two nucleator nozzles, with respect to axial positions, and at least one additional water nozzle is arranged above the at least two nucleator nozzles.
24. The snow lance as claimed in claim 23, wherein the at least one water nozzle and the at least one additional water nozzle can be charged individually with water in the different positions.
25. The snow lance as claimed in claim 23, wherein the snow lance contains a hollow cylindrical tubular part for forming the mixing chamber, to which the at least one nucleator nozzle is connected, the tubular part is arranged in the lance body axially parallel to the lance body.
Description
(1) The invention is explained in more detail below in exemplary embodiments and by way of the drawings, in which:
(2) FIG. 1: shows a schematic illustration of a snow-making process;
(3) FIG. 2: shows a cross section through a nucleator nozzle according to the invention;
(4) FIG. 3: shows the course of the water temperature in the nucleator nozzle according to FIG. 2;
(5) FIG. 4: shows a side view of a snow lance according to the invention;
(6) FIG. 5: shows a section through the snow lance according to FIG. 4 along a plane perpendicular to the axis of the snow lance;
(7) FIG. 6: shows the Mach number; homogeneous temperature and homogeneous pressure at the outlet of a nucleator nozzle according to the invention as a function of the area ratio between the core diameter and outlet opening;
(8) FIG. 7: shows a graphical illustration of the ice content as a function of the droplet section in a snow lance according to the invention,
(9) FIG. 8: shows a theoretically optimum droplet section as a function of the water temperature and the wet bulb temperature of the ambient air;
(10) FIG. 9: shows a perspective illustration of an upper part of a snow lance according to a second exemplary embodiment,
(11) FIG. 10: shows a side view of the upper end of the snow lance according to FIG. 9,
(12) FIG. 11: shows a cross section through the snow lance in the region of the nucleator nozzles (section line A-A according to FIG. 10),
(13) FIG. 12: shows a top view of the snow lance according to FIG. 9,
(14) FIG. 13: shows a sectional illustration of the snow lance along the section line F-F according to FIG. 11,
(15) FIG. 13a: shows a sectional illustration of the snow lance along the section line H-H according to FIG. 11,
(16) FIG. 14: shows a further plan view of the snow lance together with the illustration of a further section line,
(17) FIG. 15: shows a sectional illustration of the uppermost end of the snow lance along the section line B-B according to FIG. 14,
(18) FIG. 16: shows a detail C from FIG. 15,
(19) FIG. 17: shows a perspective illustration of a tubular part and three nucleator nozzles for the snow lance according to FIG. 9,
(20) FIG. 18: shows a side view with a partial section of the tubular part in an enlarged illustration,
(21) FIG. 19: shows a cross section through the nucleator nozzle according to FIG. 17 in a greatly enlarged illustration,
(22) FIG. 20: shows a side view of a lance body for the snow lance,
(23) FIG. 21: shows a cross section through the lance body (section line H-H according to FIG. 20), and
(24) FIG. 22: shows a further cross section through the lance body (section line G-G according to FIG. 20).
(25) FIG. 1 shows schematically the production of artificial snow with a snow lance. Ice nuclei 28 are produced in a nucleator nozzle 20 or 50. Water droplets 32 are produced in a water nozzle 30. The water droplets 32 move to a germination zone E via a droplet section 31. The ice nuclei 28 move to the germination zone E via an ice nuclei section 21. In the germination zone E, the water droplets 32 come into contact with the ice nuclei 28 and are seeded. On the route via the droplet section 31, the water droplets 32 which are atomized by the water nozzle 30 are cooled. The water droplets seeded with ice nuclei subsequently solidify in a solidification zone 40 and, after a dropping height H of approximately 10 meters, typically fall to the ground as snow.
(26) FIG. 2 shows in cross section a nucleator nozzle 20 according to the invention. The nucleator nozzle 20 has a lateral water inlet opening 22 and an axial compressed air inlet opening 24. The water inlet opening 22 opens approximately perpendicularly into a nozzle channel 25. The compressed air inlet opening 24 lies on the axis of the nozzle channel 25.
(27) The nucleator nozzle 20 is designed as a convergent-divergent nozzle. That is to say, the nozzle channel 25 tapers in diameter in a first section to a core diameter 26. In a second, expanding region 27, the nozzle channel 25 expands again from the core diameter 26 to an outlet opening 23.
(28) In the exemplary embodiment shown in FIG. 2, the nozzle channel is designed with a round cross section. The diameter DM of the compressed air inlet opening 24 is 2.0 mm. The diameter DLW of the water inlet opening 22 is 0.15 mm. The cross sectional diameter DK of the nozzle channel 25 in the region of the core diameter 26 is 0.85 mm while the cross sectional diameter DA of the nozzle channel 25 in the region of the outlet opening 23 is 2.5 mm. According to the invention, the ratio between the cross sectional area in the region of the outlet opening 23 and in the region of the narrowing 26 is selected to be as high as possible. In the present exemplary embodiment, the ratio is approx. 9:1.
(29) During correct operation of the nucleator nozzle, air is introduced through the compressed air inlet opening 24 at a pressure of 6 to 10 bar (absolute air pressure) in a quantity of up to at maximum 50 standard liters (standard 1) per minute. When typically 6 nucleator nozzles are used per lance, a maximum air consumption of 300 standard liters (standard 1) per minute is produced. Water is introduced through the water inlet opening 22 at a pressure of between 15 and 60 bar (absolute air pressure) into the nozzle channel 25. With the abovementioned pressures, mass flow ratios of the mass flow of air and water of approx. 0.6 to 1.9 are produced in the nucleator nozzle. However, in certain cases, mass flow ratios of the mass flow of air and water of 0.3 to 1.7 are also conceivable.
(30) In the area ratio shown in FIG. 2 between the taper 26 and outlet opening 23 and at a full cone angle of approx. 20 in the expanding region 27, a pressure of approx. 0.2 bar is produced in the expanding region 27 with the abovementioned operating parameters. With the area ratio remaining constant, the angle can be selected as desired within a certain range, but smaller angles are preferred. The associated longer residence time in the nozzle allows the entrained water droplets more time to cool.
(31) FIG. 3 shows schematically the operation of the nucleator nozzle 20 from FIG. 2 for producing ice nuclei. In the example adopted in FIG. 3, the water temperature T.sub.W is originally approximately 2 C. By means of the cross sectional narrowing and subsequent widening, the water is cooled by the compressed air. Cooling takes place to typically 1 C. to 2 C. Said cooling is less than the cooling of 8 C. to 12 C. aimed for with conventional nucleator nozzles. Accordingly, the consumption of compressed air is significantly smaller with the nucleator nozzle 20 according to the invention.
(32) Owing to the specific selection of the geometry in the widening region 27, a relatively large negative pressure is produced up to the outlet opening 23. At the same time, pressure-compensating surges are formed in a specific manner in the region 29, said surges assisting the formation of the ice nuclei and initiating solidification. MS denotes a mixing section for the air-water mixture of the mixing chamber of the nozzle channel 25. In the present exemplary embodiment, the mixing section MS is approximately 3.5 times larger than the diameter DM of the nozzle channel in the region of the mixing section. Relatively long mixing sections lead to an advantageous, finely dispersed droplet flow.
(33) The nucleator nozzle shown in FIG. 2 may in principal be used for producing ice nuclei in snow guns or in snow lances.
(34) FIG. 4 shows a snow lance 1 which is provided with three nucleator nozzles 20 (only one nucleator nozzle 20 is visible in the side view in FIG. 4). The snow lance 1 has a lance body 10. The lance body 10 is substantially formed with a cylinder geometry. At one end of the lance body 10, the nucleator nozzles 20 are arranged such that they are directed radially outward over the circumference of said lance body.
(35) In addition, two groups of water nozzles 30, 30 are arranged on the lance body 10. In the side view in FIG. 4, only one water nozzle of one group is in each case visible. Typically, three water nozzles 30 or 30 per group are arranged uniformly at a distance of 120 over the circumference of the lance body 10.
(36) The water nozzles 30 or 30 are arranged inclined with respect to a plane perpendicular to the axis A of the lance body 10. In this case, the angle of the water nozzles 30 arranged further from the nucleator nozzle 20 is selected to be smaller than the angle of the water nozzles 30 located closer to the nucleator nozzle 20. Typically, the angle of the water nozzles 30 is approximately 30 and the angle of the water nozzles 30 is approximately 50.
(37) After exiting from the nucleator nozzle 20, ice nuclei pass through an ice nuclei section 21. After passing through a droplet section 31 or 31, the water droplets produced with the water nozzles 30 or 30 meet ice nuclei in the germination zone E.
(38) In the exemplary embodiment shown, the droplet section 31 is approximately 70 cm. The droplet section 31 is approximately 50 cm. The ice nuclei section 21 is approx. 25 cm.
(39) Owing to the water nozzles 30 or 30 being arranged relatively far from the nucleator nozzles 20, relatively large droplet sections 31 or 31 are produced. The water droplets formed with the water nozzles 30 or 30 therefore have sufficient time to cool to the necessary temperature. In principle, the droplet section 31, 31 and the ice nuclei section 21 can be selected to be of any length above a lower limit of typically approximately 20 cm. The upper limit is provided by the jets still having to meet in the germination region E. Depending on the field of application, it may therefore be expedient to design the nucleator nozzle 20 as a circular jet nozzle (i.e. with a round cross section in the outlet region) or as a fan jet nozzle (i.e. with an elliptical cross section in the outlet region).
(40) The arrangement of the water nozzles 30 or 30 in two groups at different distances from the nucleator nozzle 20 permits different operating modes depending on the wet bulb temperature of the surroundings. Typically, both groups of water nozzles 30 and 30 are used at lower wet bulb temperatures. At lower temperatures, a shorter droplet section 31 is sufficient. At higher wet bulb temperatures, only the water nozzles 30 which are further away are used. Owing to the longer droplet section 31, sufficient cooling is nevertheless ensured.
(41) At operating pressures of 15 to 60 bar, the water consumption of a nozzle 30 or 30 is customarily between 12 and 24 liters of water per minute. In the exemplary embodiment, at high wet bulb temperatures of the surroundings of typically 4 C. to 1 C., snow can be made with three water nozzles 30 of the groups which are further away and using approx. 36 to 72 liters of water per minute. After the water nozzles 30 of the closer group are switched on below typically 4 C., consumption of approx. 72 to 144 liters of water per minute is produced. For even lower temperatures, at least one further water nozzle group is provided, but is not shown here.
(42) Means of supplying air and water for the individual nozzles are arranged in the lance body 10 in a manner known per se. Such supply means are customary for a person skilled in the art. They are therefore not described in detail here.
(43) The various components described are manufactured from metal. Partially anodized aluminum is typically used for the body of the nucleator nozzle and of the water nozzle and also of the snow lance.
(44) FIG. 5 shows a section through a plane perpendicular to the axis A of the lance body. The lance body 10 is of substantially cylindrical design. Three water nozzles 30 are arranged regularly over the circumference of the lance body 10 at an angular spacing of 120. Various supply lines (not described specifically) for air and water are shown in the interior of the lance body 10.
(45) FIGS. 6 to 8 show various measurement results from which the significantly greater efficiency of the nucleator nozzle and snow lance according to the invention is apparent.
(46) FIG. 6 shows a Mach number, the homogeneous temperature and the homogeneous pressure in the medium in the region of the outlet opening 23 of the nucleator nozzle 20 (see FIG. 2) as theoretical values. Homogeneous here means that the temperatures of air and water in the nozzle have already been fully equalized. In reality, this will never be the case. The temperatures shown here are therefore significantly lower than the anticipated water temperatures. The geometry of the nucleator nozzle 20 is selected in such a manner that the Mach number lies within the range of at least approximately 2 to 2.5. In the region of the outlet opening, the pressure in the emerging medium is approximately 0.2 to 0.6 bar. The specified pressure and temperature values and the Mach number depend on the area ratio A.sub.A/A.sub.K between the cross sectional area in the region of the outlet opening 23 and in the region of the narrowing 26. The area ratio found to be preferred on the basis of tests is approx. 9:1.
(47) In the lowermost illustration in FIG. 6, two different curves are also shown as a function of the air pressure in the nucleator nozzle 20. Comparable results are produced at an air pressure of 6 bar and at 10 bar.
(48) All three illustrations according to FIG. 6 also show the curves for two different mass flow ratios ALR between the air and water. Said mass flow ratios lie within the abovementioned operating range limits which arise from the typically prevailing pressure ranges of water and air and from the geometry.
(49) FIG. 7 shows the average ice content in percent in a region at a horizontal distance of approx. 3.5 m downstream of the nozzle outlet. The ice content increases if the droplet section increases. Given a fixed ice nuclei section 21 of 25 cm and a water temperature of 1.7 Celsius, at a wet bulb temperature of the surroundings of 2 C. an ice content which rises from approx. 4.5% to approx. 6% is produced in a droplet section of 10 or 50 cm. The effect is even more pronounced at a lower wet bulb temperature of 7 C.: in this case, if the droplet section is lengthened from approx. 10 to 50 cm, the ice content increases from approx. 12 to virtually 15%.
(50) FIG. 8 also shows the theoretically optimum droplet sections, which are determined by experimentation, as a function of various water temperatures for various wet bulb temperatures. The theoretically optimum droplet section is understood as meaning the section in which the water droplets from the water nozzles 30 and 30 can be cooled precisely to 0 C. This ensures that no more ice nuclei are melted during the encounter in the germination zone, and therefore the best snow-making results should be expected. As FIG. 8 shows, optimum snow-making can be achieved with a water temperature of 1 Celsius with a droplet section in the region of 50 cm to 1 m and at a wet bulb temperature of the surroundings of up to 2 C.
(51) FIG. 9 shows a further snow lance 1 which differs from the snow lance according to FIG. 4 inter alia in that additional water nozzles 30 are arranged above the nucleator nozzles, which are denoted by 50. The water nozzle and nucleator nozzle geometry is essentially the same. The snow lance therefore differs by comparatively long ice nuclei sections and droplet sections. The ice nuclei section here is also intended to be at least 10 cm, in particular approximately 20 to 30 cm and the respective droplet sections of the water nozzles 30 and/or 30 are intended to be at least 20 cm, in particular approximately 40 to 80 cm. The droplets of the additional water nozzles 30 are seeded in a second germination zone by means of already frozen droplets from the water nozzles 30 and/or 30 and remaining ice nuclei from the nucleator nozzles (20/50). The snow lance 1 has an alternative arrangement, which is described in more detail below, for producing ice nuclei.
(52) As emerges from FIG. 10, the nucleator nozzles 50 are fastened in a head part 41. By way of example, the fastening takes place via a screw connection. To screw in the nozzle 50, two blind holes can be seen next to the outlet opening 23 as workpiece receptacles (cf., for example, FIG. 19 below). Said head part 41 is screwed on to the lance body.
(53) As emerges from FIG. 11, the three nucleator nozzles 50 of the arrangement for producing ice nuclei are fed by a common channel. A water-air mixture can be conducted through said channel, the mixture dividing in the channel division 43 and being supplied to the nucleator nozzles 50. A nozzle inlet opening of the nozzle channel of the nucleator nozzle 50 is denoted by 51. Said nucleator nozzles 50 differ from the nucleator nozzles according to the first exemplary embodiment (cf. FIGS. 2, 3) particularly in that the water is not conducted into the nozzle channel via a lateral, separate input opening. The basic conception of the nozzle channel geometries of the nucleator nozzles 50 remain more or less the same. The nucleator nozzle 50 is therefore likewise configured as a convergent-divergent nozzle in which the ratio of the cross sectional area of the outlet opening to the cross sectional area of the nozzle channel in the region of the core diameter is at least 4:1 and preferably approximately 9:1. The individual nucleator nozzles are each connected in terms of flow to supply channels 56 which are connected to a central channel 55 in the region of the channel division 43. It can furthermore be readily seen in FIG. 11 that the water nozzle 30 is configured as a fan jet nozzle.
(54) It can be seen from the top view according to FIG. 12 (and also from FIG. 14) of the snow lance 1 that the three water nozzles 30 and 30 in each case (and of course also the nucleator nozzles which cannot be seen here) are distributed over the circumference of the lance body 10.
(55) FIG. 13 shows a longitudinal section through the snow lance 1. In order to form a mixing chamber, a tubular part 44 which is of approximately hollow cylindrical design and into which compressed air can be supplied via a compressed air inlet opening 24 is provided. The water is conducted from the side into the mixing chamber of the tubular part 44. The tubular part 44 is surrounded on the surface area side by an outer tube 46 which has two bores 48 for the entry of water. A sleeve-shaped filter element 49 is arranged between the outer tube 46 and the tubular part 44 (cf. FIG. 18 below). As can be seen, water for all of the nucleator nozzles is injected via a common mixing chamber. Furthermore, the arrangement has a common central water filtering means 49 for the three nucleator nozzles. This has the advantage thatin comparison to the arrangement according to the first exemplary embodiment as per FIG. 2a comparatively large water inlet opening can be selected. This has advantages inter alia in terms of production. However, a further advantage consists in the filtration of the supplied water being able to be simplified. The mixing chamber system according to the second exemplary embodiment enables, for example, the coarser and larger filter to be used.
(56) It is apparent with reference to FIGS. 13 and 13a how the water is conducted through the snow lance and the water and nucleator nozzles are fed. It can be seen in FIG. 13a how the water is conducted in 45 (and 45) upward into the head part where it is deflected. In this case, the water feeds the nucleators and at the same time icing up is prevented by the head being heated. The water is then conducted again to the foot of the lance where it can be distributed into three channels by means of valves and can be conducted upward again (see FIGS. 20-22). The direction of the water mass flows is indicated by arrows. The three groups of water nozzles (30, 30, 30) can each be charged individually with water by means of valves (not illustrated). A channel 59 which extends in the axial direction of the lance body and serves to feed the upper water nozzles (30) can be seen in FIG. 13. A cutout in the outer casing of the lance body, via which the water can pass into an annular channel, formed by an annular element 54, is denoted by 57. The annular element 54 has recesses on the circumference, into which the water nozzles can be screwed (cf., for example, FIG. 9 or 10). The nozzles 30 are also fed in the same manner by an annular channel. A compressed air supply pipe is denoted by 58. The compressed air passes from said channel 58 via a candle filter 52 into the tubular part 44.
(57) FIGS. 15 and 16 show the snow lance 1 in a further longitudinal section, the snow lance being depicted true to scale in FIG. 16. The design of the nozzle channel of the arrangement for producing ice nuclei can in particular be readily seen therefrom. The water-air mixture is conducted along a first mixing section MS to the channel division 43. Said mass flow is then deflected and divided until it finally passes through the respective nozzle channels of the nucleator nozzles 50 to the outlet opening 23. In this case, the mixing section MS is approximately 12 times larger than the diameter of the nozzle channel in the region of the mixing section. Particularly advantageous results can be obtained if the entire mixing section MS+MS is at least 12 times larger than the diameter of the nozzle channel in the region of the mixing section. It has been shown that a mixing section which is at least three times larger than the diameter of the nozzle channel in the region of the mixing section MS may be advantageous. The mixing chamber of the tubular part is adjoined by a short channel 55 which is assigned to the head part and has the same channel diameter, said channel being divided into three channels 56. The channels 56 (mixing section MS) and therefore also the nucleator nozzles 50 are oriented at a right angle to the tubular part 44. In the present example, the cross sectional area in the region of the mixing section MS is approximately 7 times larger than the overall cross sectional area of the three nucleator nozzles in the region of the core diameter.
(58) FIG. 17 shows the tubular part 44 and the three nucleator nozzles 50 of the arrangement for producing ice nuclei for the snow lance in a type of exploded illustration.
(59) Details of a tubular part 44 can be gathered from FIG. 18. The water inlet opening 22 is arranged here approximately centrally in the tubular part 44 with respect to the axial direction. The filter element 49 may be composed of a wire mesh. A central filtering means of this type may be configured to be relatively coarse, as a result of which the range of use can be expanded. The mesh width of a wire fabric filter (or hole width in general) may be, for example, approximately 0.1 mm. As can be seen, the filter element 49 is spaced apart from the outer wall of the tubular part 44, as a result of which an annular gap is formed. The water finally passes from the annular gap via the water inlet opening 22 in the tubular part 44 into the mixing chamber and is entrained by the compressed air stream and mixed therewith. The diameters of the bores 48 are many times larger than the diameter of the water inlet opening 22. The diameter, denoted by DLW, of the water inlet opening 22 may be, for example, 0.25 mm or 0.5 mm, depending on the intended use. A candle filter 52 is arranged in the region of the compressed air inlet opening 24 in order to clean the air brought up to this point.
(60) Structural details of a nucleator nozzle 50 can be gathered from FIG. 19. The nozzle 50 is designed as a single-piece component which has an external thread with which the nozzles can be fastened into corresponding receptacles on the head part. The present nozzle has the following characteristic data by way of example: outlet diameter D.sub.A=2.5 mm, core diameter D.sub.K=0.85 mm and inlet diameter D.sub.M=2.1 mm. The diameter of the channel (56) (not shown here) opening into the nozzle is 2.0 mm. The length, denoted by LE, of the narrowest cross section is approx. 5.4 mm. Owing to the relatively long channel section with the narrowest cross section (LE) and because of the comparatively long outlet cone, the water droplets have sufficient time for cooling, as a result of which the production of ice nuclei can be optimized.
(61) FIG. 20 shows a lance body 10. FIGS. 21 and 22 show a section through the lance body in two different axial positions. The lance body 10 is as a hollow profile extending in the axial direction and containing five circular cavities 53, 53, 58, 59, 59 and four non-circular cavities 45, 45, 47, 47. In this case, the central cavity 58 serves as a supply pipe for the compressed air for the nucleator nozzles. In the cavities 45 and 45, water is conducted upward to the lance head (not shown here) where it is deflected. The water is then conducted downward via the cavities 47, 47 to a valve arrangement (not shown). Depending on activation, the water passes to the round channels 59 and/or 59 which feed the water nozzles arranged below the nucleator nozzles. An elongated hole 57 which produces the connection between the cavity or channel 59 and the lower water nozzles (30) (not shown here) in terms of flow can be seen in FIG. 21. The cavity or channel 59 serves for feeding the upper water nozzles (30). The channels 53 and 53 serve to feed the additional water nozzles (30) which are arranged above the nucleators.
(62) It can be seen from FIG. 22 and FIG. 20 how the bore 48 with which water can be supplied to the tubular part 44 for feeding the nucleators, can be produced. Said bores can be produced in a simple manner by a drilling operation from the outside of the lance body. The holes produced in the process on the outer casing of the lance body 10 then merely have to be closed. FIG. 22 indicates a filling of the holes by a shaded area 60.
