Blizzard generation system and blizzard generation method

Abstract

To provide a snowstorm generation system that enables blowing a snowstorm in a desired height-range of a test piece, using thin ice snowflakes having a snow accretion property in a nearly natural state.SOLUTION: A snowstorm generation system includes: a wind tunnel facility that causes an airflow to flow from a contraction flow tunnel 314 toward a stationary vehicle V; and a thin ice snowflake manufacturing device that is provided between the contraction flow tunnel 314 and the stationary vehicle V. The thin ice snowflake manufacturing device includes: a water sprayer that sprays water toward an inner periphery cooling surface of a fixed hollow cylinder; a blade with a tip thereof separated at a prescribed interval from the inner periphery cooling surface; and rotation driving means that rotates the water sprayer and the blade concentrically with the fixed hollow cylinder. In the water sprayer and the blade, with an interval mutually spaced at a prescribed angle in a circumferential direction of the fixed hollow cylinder, a discharge port is provided in a lower end part that allows the thin ice snowflake to drop naturally, the thin ice snowflake being generated from a thin ice layer formed on the inner periphery surface through peeling by means of the blade. The snowstorm generation system further comprises a booster airflow generation device that carries, on an airflow generated within a wind tunnel 16, and jets the naturally dropping thin ice snowflakes, from a vent of the contraction flow tunnel 314.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a snowstorm generation system and a snowstorm generation method. More specifically, the present invention relates to a snowstorm generation system and a snowstorm generation method capable of spraying a snowstorm using thin ice and snow flakes having a snow deposition property close to a natural state onto a desired height range of a specimen.

Background Art

[0002] Conventionally, environmental tests in a mode simulating a running state have been conducted for various purposes by spraying a jet air flow generated in a wind tunnel toward a specimen. As one of them, there is an environmental test for evaluating the influence of snow on a specimen by placing artificial snow on a jet air flow and causing the artificial snow to fly or snow toward a specimen, for example, a stationary vehicle. It is classified into types according to the artificial snow used.

[0003] For example, Patent Document 1 discloses a snowstorm generation system using artificial snow of crushed ice particles. In this snowstorm generation system, ice pieces made by an ice maker are crushed by a crusher to become ice particles having a predetermined particle size, are pumped by an air flow through a snow supply pipe, are branched into a plurality of branch pipes by a distribution device, and in each branch pipe, are made into wet snow having a predetermined moisture content by a wet snow device and reach a blowing nozzle. The snow blown out from the blowing outlet of the blowing nozzle rides on the air flow and flows as a snowstorm along the traveling direction of the air flow. The snowstorm hits a diffusion surface disposed so as to face the blowing outlet at a predetermined position in front of the traveling direction of the air flow outside the blowing outlet. Since the diffusion surface is formed in a conical shape made of a material having poor adhesion to snow and with a top portion facing closer to the blowing outlet so as to have poor adhesion to snow, the snowstorm is guided along the diffusion surface without adhering to the diffusion surface, diffuses outward in all directions, and can suppress fluctuations in diffusion characteristics over time associated with adhesion to the diffusion surface. According to such a snowstorm generation system, it is possible to some extent to diffuse the snowstorm into a desired diffusion region.

[0004] On the other hand, Patent Document 2 discloses a snowfall system that utilizes crystalline snow. This crystalline snowfall system is located in a space divided vertically by a horizontally extending partition, with a crystalline snow production section in the upper part and a crystalline snowfall section in the lower part. The crystalline snow production section consists of an upper roller and a lower roller, at least one of which is rotatable. The device comprises a rotating ventilation membrane device with an endlessly stretched mesh-like membrane, and a crystalline snow shedding body whose leading edge is spaced apart from the outer surface of the mesh-like membrane near the lower roller. Below freezing point, crystalline snow is generated on the outer surface of the mesh-like membrane by moist air containing water vapor above ice saturation. The crystalline snow falling section includes a wet snow making device that wets the crystalline snow produced by the crystalline snow production section during snowfall, and a temperature and humidity control device that adjusts the temperature and humidity within the space of the crystalline snow falling section. The partition consists of a plurality of rollers arranged at predetermined intervals with their outer surfaces facing each other parallel to one another, and rotatable in a direction toward the narrowest part between adjacent rollers from above. The space above the narrowest part consists of a plurality of rollers arranged to receive the shedding crystalline snow. Each roller constitutes a rotating brush with bristles implanted on its outer surface, and the partition is formed when the brushes of the adjacent rollers overlap at the narrowest part between them.

[0005] In this type of crystalline snowfall system, in the upper part of a space divided vertically by a horizontally extending partition, humid air containing water vapor above ice saturation at below freezing point generates frost-like crystalline snow on the outer surface of a mesh-like membrane during the rotation of the rotating ventilated membrane device. Near the lower roller, the crystalline snow generated on the outer surface of the mesh-like membrane can be removed by a crystalline snow removal device. In this case, depending on the rotation speed of the rotating ventilated membrane device and the distance between the outer surface of the mesh-like membrane and the leading edge of the crystalline snow removal device, the generated crystalline snow may be removed by the crystalline snow removal device in the form of large snow flakes. The large snow flakes are received in the space above the narrowest point between adjacent rollers, and as the adjacent rollers rotate toward the narrowest point between them, the large snow flakes are guided downwards through the narrowest point. At this time, the large snow flakes are flicked away by the tip of the rotating brush, and the large snow flakes are broken down into smaller snow flakes without the crystals themselves being destroyed. In addition, at the narrowest point between adjacent rollers, the brushes overlap, forming a partition. This prevents the rising airflow from reaching the upper part of the space by raising the temperature in the lower space to wet the crystalline snow during snowfall. This prevents the snowfall from being obstructed by the rising airflow and does not hinder the growth of crystals in the snowmaking section. Thus, it is possible to wet the crystalline snow during snowfall while preventing the formation of large snow flakes.

[0006] However, the blizzard generation system and snowfall system described above have the following technical problems due to the artificial snow they use. Firstly, in the blizzard generation system described above, the artificial snow used is considerably different in quality from the dendritic crystalline snow that falls naturally or the natural snow formed by the entanglement of dendritic crystalline snow, making it difficult to conduct tests that simulate natural snow. More specifically, crushed ice particles have higher hardness and different adhesion properties compared to natural snow, making it difficult to accurately evaluate the adhesion of snow to a test specimen. Next, in the above snowfall system, since crystalline snow is used, unlike the thin ice and snowflakes in the blizzard generation system described above, the snow quality, especially its adhesion, is not far removed from natural snow. However, the crystalline snow production equipment is large-scale, and it is technically difficult to continuously supply the amount necessary for environmental tests, such as tests in which blizzards are blown onto stationary vehicles using airflow generated in a wind tunnel, on the spot and at the time.

[0007] In particular, in Patent Document 1, when artificial snow in the form of ice granules is blown towards a test specimen using conveyed air via a snow supply pipe in a wind tunnel, the height level of the artificial snow can be adjusted to some extent. However, in the case of thin ice snow fragments that are closer to natural snow, the bulk density is low, they are soft, and the surface moisture content is high. Therefore, if they are to be transported using conveyed air via a snow supply pipe, the thin ice snow fragments may adhere to the inner surface of the snow supply pipe, causing transport to be hindered, or in some cases, the snow supply pipe to become blocked. In this regard, if one attempts to generate thin ice and snowflakes in a wind tunnel without using transport air via a snow supply pipe, and then use the airflow generated in the wind tunnel to carry them away, the following technical problems will arise. In other words, if the simulated travel speed is set to the airflow velocity at the outlet of the constriction tunnel, the airflow velocity in the upstream straightening tunnel will be reduced to a fraction of that velocity. When thin ice and snow fragments are allowed to fall naturally into the straightening tunnel using a thin ice and snow fragment generating device, they will not be carried by the airflow within the straightening tunnel and will instead accumulate at the bottom of the tunnel. This can hinder the smooth execution of environmental tests in which a blizzard of thin ice and snow fragments is blown onto the test specimen. In this regard, if thin ice and snowflakes are generated outside the wind tunnel and carried away by the airflow generated inside the wind tunnel, such snow accumulation can be avoided to some extent due to the high airflow velocity at the outlet of the wind tunnel. However, it is difficult to adjust the desired height level or range of the snowflake blizzard blown onto the test specimen. Furthermore, while it is possible to some extent to adjust the concentration of blizzard particles blown onto a vehicle in the vertical direction by installing multiple sets of nozzles in the vertical direction within the wind tunnel, arranging the multiple nozzles in each set at predetermined intervals in the horizontal direction, and individually adjusting the amount of ice particles blown from each set of nozzles, installing multiple nozzles in the wind tunnel disrupts the airflow generated within the wind tunnel in the first place, making it difficult to simulate the situation in which blizzards caused by natural snow blow onto a moving vehicle. [Patent Document 1] Japanese Patent Publication No. 2015-143583 [Patent Document 2] Japanese Patent Publication No. 2018-115794 [Disclosure of the Invention] [Problems that the invention aims to solve]

[0008] In view of the above technical problems, the object of the present invention is to provide a blizzard generation system and a blizzard generation method that can blow a blizzard using thin ice and snow fragments having snow accumulation properties close to those of natural conditions onto a test specimen at a desired height range. [Means for solving the problem]

[0009] To achieve the above objectives, the blizzard generation system of the present invention A wind tunnel system that directs the airflow generated inside the wind tunnel towards the test specimen through a straightening tunnel and a constricting tunnel, It has a thin ice and snowflake manufacturing device installed at the top of the flow straightening tunnel, The thin ice and snow flake manufacturing apparatus includes a water spray sprayer that sprays water toward the inner cooling surface of a fixed cylinder, A blade whose tip is separated from the inner cooling surface at a predetermined distance, The device comprises a water spray nozzle and a rotational drive means for rotating the nozzle and the blade concentrically with the fixed cylinder, The water sprayer and the blade are spaced apart from each other at a predetermined angular distance in the circumferential direction of the fixed cylinder. An outlet is provided at the lower end, facing the wind tunnel, to allow the thin ice and snow fragments generated by peeling off the thin ice layer formed on the inner cooling surface with the blade to fall naturally. Furthermore, the system includes a booster airflow generator that carries the thin ice and snow fragments that naturally fall from the thin ice and snow fragment manufacturing apparatus into the wind tunnel, using the airflow generated in the wind tunnel, and blows them out from the outlet of the constricted flow tunnel.

[0010] With the blizzard generation system having the above configuration, it is possible to simulate driving by directing the airflow generated in the wind tunnel through the wind tunnel towards a stationary vehicle. In this system, a thin ice and snowflake manufacturing device is installed at the top of the rectifying tunnel, and a water spray and blades are rotated concentrically with a fixed hollow cylinder by a rotary drive mechanism. By spraying water towards the inner cooling surface of the fixed hollow cylinder with the water spray, a thin ice layer is formed on the inner cooling surface. At the same time, the thin ice layer is peeled off by the blades, which are spaced at a predetermined angular interval from the water spray and the fixed hollow cylinder in the circumferential direction, thereby generating thin ice and snowflakes. The generated thin ice and snowflakes are then allowed to fall naturally from the discharge port at the lower end, making it possible to carry the thin ice and snowflakes towards a stationary vehicle using the airflow generated in the wind tunnel. In contrast to conventional blizzard simulations using artificial snow made from ice particles, which struggle to reproduce natural snow accumulation conditions on simulated vehicles, this invention utilizes the airflow generated by a booster airflow generator to guide thin ice fragments that naturally fall into the wind tunnel from a thin ice fragment manufacturing device to the outlet of a constricted flow tunnel where the airflow velocity increases. The fragments are then carried by the airflow generated in the wind tunnel and blown out from the outlet of the constricted flow tunnel. This allows for smooth testing of blizzard conditions using thin ice fragments, simulating driving with a stationary vehicle while simultaneously blowing a blizzard of thin ice fragments onto the stationary vehicle at a desired level and height range. In this specification, a blizzard refers to snow that is carried by airflow generated in a wind tunnel and blown toward a stationary vehicle. In this sense, it is distinguished from snow that falls naturally due to gravity, and the direction of the blown snow is not usually horizontal.

[0011] Furthermore, it is preferable to have multiple thin ice and snowflake manufacturing devices, each of which can be independently adjusted horizontally on the flow straightening cavity. Furthermore, the wind tunnel preferably has a conveyor that guides the thin ice and snow fragments falling from the thin ice and snow fragment manufacturing apparatus toward the constricted flow tunnel, and the conveyor preferably has a drive roller and a driven roller that are spaced apart from each other in the direction of the airflow in the wind tunnel and whose respective axis of rotation is perpendicular to the direction of the airflow in the wind tunnel, a conveyor belt stretched between the drive roller and the driven roller, and a rotational drive means that rotates the axis of rotation of the drive roller so that the upper side of the conveyor belt is translated in the direction of the airflow in the wind tunnel. Furthermore, the upper surface of the conveyor belt is preferably positioned so as to overlap with the discharge port position of the thin ice and snowflake manufacturing apparatus in the longitudinal direction of the straightening cavity.

[0012] Furthermore, the airflow outlet nozzle of the booster airflow generator is preferably located in the space above the outlet of the constriction cavity within the straightening cavity. In addition, it is preferable that the booster airflow generator be able to adjust the size of the booster opening and / or the booster airflow velocity according to the height of the snow flying at the outlet. In this case, the booster airflow generator is better configured to adjust the airflow rate by changing the size of the booster opening and / or the booster airflow velocity according to the amount of thin ice and snow fragments per hour falling into the wind tunnel from the thin ice and snow fragment manufacturing device and / or the size of the thin ice and snow fragments. Furthermore, the airflow rate from the booster airflow generator should be set according to the airflow velocity generated in the wind tunnel. Furthermore, it is preferable to set the distance of the test specimen from the outlet of the constricted flow tunnel and / or adjust the airflow rate of the booster airflow generator according to the desired range of snowflake heights on the test specimen.

[0013] Furthermore, the thin ice and snow piece manufacturing device is provided above the rectifying cavity, is fitted to a rail along the extending direction of the wind tunnel provided above the rectifying cavity, and is preferably movable between the rectifying cavity and the stationary vehicle together with the gantry. In addition, the booster air flow generating device includes an air flow generating drive source, an air flow blowing nozzle that blows out the air flow generated by the air flow generating drive source, and an air flow supply pipe that communicatively connects the air flow generating drive source and the air flow blowing nozzle. The air flow blowing nozzle is preferably directed toward the direction of the air flow generated in the wind tunnel. Also, the wind tunnel is a return type, and the outlet and the inlet of the constricting cavity are arranged opposite to each other, and a stationary vehicle is preferably arranged between the outlet and the inlet. Furthermore, the thickness of the thin ice and snow pieces is preferably 0.1 mm to 0.2 mm so that they can ride on the wind and be blown as flying snow.

Best Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments of the snow blowing generation system of the present invention will be described in detail below with reference to the drawings. As shown in FIG. 1, the snow blowing generation system 10 uses artificial snow made of thin ice and snow pieces, and is configured to simulate flying snow by placing the artificial snow on the air flow from behind and directing it toward the vehicle V as a test specimen. For this purpose, it has a wind tunnel facility, a thin ice and snow piece manufacturing device 18, a booster air flow generating device 100, and a conveyor 400. In particular, when continuously supplying a required amount of flying snow having a predetermined snow quality, where the size and moisture content of the thin ice and snow pieces are the main influencing factors, to diffuse over the entire height of the vehicle V and possibly achieve a desired flying snow concentration distribution in the height direction of the vehicle V, it is required to manufacture and quickly supply a group of thin ice and snow pieces used as artificial snow immediately before the test under predetermined temperature and humidity control.

[0015] In general terms, the blizzard generation system 10 generates an airflow MF towards the vehicle V inside the wind tunnel 16, produces thin ice and snowflake-shaped artificial snow using a thin ice and snowflake manufacturing device 18 (described later), and uses an airflow J generated horizontally towards the vehicle V by a booster airflow generator 100 (described later) to guide the falling thin ice and snowflakes toward the constriction tunnel 314. Additionally, a conveyor 400 (described later) guides the thin ice and snowflakes that have fallen onto the upper surface of the conveyor belt toward the constriction tunnel 314, where the increased speed of the airflow MF flowing from the wind tunnel 16 toward the constriction tunnel 314 causes the snowflakes to be blown out as a blizzard from the outlet 316 of the constriction tunnel 314.

[0016] The wind tunnel 16 is an open-type recirculating wind tunnel, and is formed in a roughly rectangular shape in plan view, comprising an open-type measurement chamber 300 in which the vehicle V to be measured is placed, and four bent sections 302, 304, 306, and 308 (bent sections). The airflow MF generated by the blower 25 flows through the second diffusion cylinder 310, the third bending cylinder 306, the fourth bending cylinder 308, the straightening cylinder 312, and the constricting cylinder 314, and into the measurement chamber 300 through the outlet 316 that opens into the measurement chamber 300. The outlet 316 and the receiving port 317 are positioned opposite each other in the measurement chamber 300, and the airflow flows in the order of receiving port 317, first bending cylinder 302, and second bending cylinder 304. The airflow MF blown by the blower 25 first reduces the overall airflow velocity (dynamic pressure) and increases the pressure (static pressure) in the intermediate section. Then, by passing it through the retraction cylinder 314, an airflow MF with a sufficient volume (velocity) for measurement can be blown out from the outlet 316 into the measurement chamber 300.

[0017] As a result, as will be explained later, thin ice and snowflakes are supplied as flying snow towards the vehicle V within the measurement chamber 300, carried by the airflow MF from behind it, and by adjusting the wind speed of the airflow MF with the blower 25, it is possible to simulate a moving vehicle V even though the vehicle V is stationary. Furthermore, in the case of the recirculating wind tunnel 16 for snow environment testing, a separate snow repair device 38 is provided downstream of the vehicle V to separate and recover the snow after the test. In any case, a region is deliberately provided downstream of the vehicle V where the airflow MF is not rectified in order to separate the snow through gravity or inertial effect.

[0018] Next, as shown in Figures 2 to 4, the thin ice snowflake manufacturing apparatus 18 includes a water spray spray 24 that sprays water toward the inner circumferential surface 56 of a fixed hollow cylinder 20, a blade 28 whose tip 26 is separated from the inner circumferential surface 56 by a predetermined distance, and a rotational driving means 30 that rotates the water spray spray 24 and the blade 28 concentrically with the fixed hollow cylinder 20. The water spray spray 24 and the blade 28 are separated from each other by a predetermined angular distance θ in the circumferential direction of the fixed hollow cylinder 20, and an outlet 32 ​​is provided at the lower end to allow the thin ice snowflakes S generated by peeling off the thin ice layer L formed on the inner circumferential surface 56 with the blade 28 to fall naturally.

[0019] The thin ice snowflake manufacturing device 18 is installed at the top of the straightening tunnel 312, and the thin ice snowflakes produced by the thin ice snowflake manufacturing device 18 fall into the straightening tunnel 312 through an opening provided on the upper surface of the straightening tunnel 312. The thin ice and snowflake manufacturing device 18 is movable between the straightening tunnel 312 and the stationary vehicle V by airflow corresponding to the simulated travel speed. For example, by fitting the device 18 onto a rail (not shown) located above the straightening tunnel 312 and aligned with the extension direction of the wind tunnel 16, and configuring the entire frame on which the thin ice and snowflake manufacturing device 18 is installed to be movable between the straightening tunnel 312 and the stationary vehicle V, the thin ice and snowflake manufacturing device 18 can be made movable relative to the wind tunnel 16. When spraying snow onto a stationary vehicle V within a desired height range, especially when testing with the stationary vehicle V mounted on top of a dynamo roller and the tires rotating, the vehicle's position is limited, and the snowfall position cannot be adjusted by moving the vehicle itself forward or backward. Therefore, it is effective to make the thin ice snowflake manufacturing device 18 itself movable. Multiple thin ice and snowflake generating devices 18 (two in the drawing) are provided, and the horizontal position of each thin ice and snowflake generating device 18 can be adjusted independently on the flow straightening cavity 312. This makes it possible to adjust the way the numerous thin ice and snowflakes S produced by each thin ice and snowflake generating device 18 and that naturally fall into the flow straightening cavity 312 are blown by the booster airflow generator 100 and the conveyor 400 before they reach the flow constriction cavity 314.

[0020] The fixed hollow cylinder 20 has an inner cylinder 22 on which a thin layer of ice L is formed on its inner surface, and an outer cylinder 23 surrounding the inner cylinder 22. The inner cylinder 22 and the outer cylinder 23 are made of steel, and a hollow section 21 is provided between the inner cylinder 22 and the outer cylinder 23. A refrigerant is supplied to the hollow section 21 from a refrigerator 74 via pipes 76 and 78, so that the inner circumferential surface 56 of the inner cylinder 22 is cooled to a predetermined temperature by the refrigerant. The outer circumferential surface of the fixed hollow cylinder 20 is covered with a cylindrical protective cover (not shown). The fixed hollow cylinder 20 is provided with an outlet 32 ​​at its lower end 42 that allows thin ice and snow fragments S, generated by peeling off the thin ice layer L formed on the inner circumferential surface 56 with a blade 28, to fall naturally.

[0021] The connecting rod 40 is horizontally positioned to traverse the space inside the fixed hollow cylinder 20, passing through the center of the fixed hollow cylinder 20. Each end 42 of the connecting rod is provided with a connecting rod rotation mechanism 44. Near the center of the fixed hollow cylinder 20, each end 42 of the connecting rod rotation mechanism 44 is provided with a pair of blades 28-water spray 24 via a support arm 46. The connecting rod 40 rotates around the center of the fixed hollow cylinder 20 by the connecting rod rotation mechanism 44, thereby enabling each pair of blades 28-water spray 24 to move in the circumferential direction of the fixed hollow cylinder 20. The level of the connecting rod 40 relative to the fixed hollow cylinder 20 can be determined as appropriate, but as will be explained later, the upper part of the fixed hollow cylinder 20 is preferable due to the installation configuration of the connecting rod rotation mechanism 44.

[0022] The connecting rod rotation mechanism 44 provided at each end 42 is common to all, so we will describe one of them. The connecting rod rotation mechanism 44 generally comprises a pair of tires 48I and 48O arranged on either side of the connecting rod 40, a vertical rotating shaft 50 that supports each of the pair of tires 48I and 48O so that they can rotate around the center of the tire 48, a rotating shaft support part 52 that supports the vertical rotating shaft 50, and a rotation drive part 54 that rotates the tire 48. A pair of tires 48I and 48O are provided on the inner circumferential surface 56 and outer circumferential surface 58 sides of the fixed hollow cylinder 20, respectively, and are fitted into circumferential grooves 60 provided on the inner circumferential surface 56 side and circumferential grooves 60 provided on the outer circumferential surface 58 side, and are arranged so as to sandwich the fixed hollow cylinder 20 between the pair of tires 48I and 48O. The distance between the pair of tires 48I and 48O, that is, the length of the rectangular member (explained later), should be determined from the viewpoint that the connecting rod 40, and thus the two sets of blades 28 - water spray 24, can rotate smoothly in the circumferential direction of the fixed hollow cylinder 20 by the connecting rod rotation mechanism 44. The tires 48 are preferably made of ordinary rubber that has elasticity that provides shock absorption and deformation capability. More specifically, the width w of the circumferential groove 60 is set according to the width of the tire 48, preferably slightly wider than the width of the tire 48 so that the tire 48 can rotate freely around the center, and the depth d of the circumferential groove 60 is determined from the viewpoint that the connecting rod 40 and the two sets of blades 28 - water spray 24 can be supported by a total of four tires 48.

[0023] The rotating shaft support portion 52 is, for example, a rectangular member having a central support portion for each tire 48 at each of its four corners, positioned above the fixed hollow cylinder 20 so as to straddle the upper circumferential surface of the fixed hollow cylinder 20 both internally and externally, and connected to the corresponding end 42 of the connecting rod 40 on the inner circumferential surface 56 side. As a result, the connecting rod 40, the rotating shaft support portion 52, and thus each tire 48 supported by the rotating shaft support portion 52 are movable as a single unit. The rotation drive unit 54 may be, for example, a drive motor, and is directly connected to the vertical rotation shaft 50 of one of the four tires 48, making it the rotation drive tire 48, while the other tires 48 are configured as driven tires 48. Alternatively, the rotation drive unit 54 may be provided on one of the tires 48 on one side of the pair of connecting rod rotation mechanisms 44, with the remaining seven tires 48 being driven tires 48. In this case, the driven tires 48 are free to rotate relative to their corresponding vertical rotation shafts 50, while the drive tires 48 are preferably connected to the vertical rotation shafts 50, which are rotationally driven by the rotation drive unit 54, via, for example, a reduction mechanism (not shown).

[0024] With the above configuration, the connecting rod 40 and the rotating shaft support part 52 are supported by the connecting rod rotation mechanism 44, and thus the tire 48 supported by the rotating shaft support part 52 is supported. The rotation drive unit 54 causes the connecting rod 40 and thus the two sets of blades 28-water spray 24 to rotate in the circumferential direction of the fixed hollow cylinder 20. As will be explained later, the water spray 24 sprays water onto the inner circumferential surface 56 of the fixed hollow cylinder 20, and the blades 28 peel off the thin ice layer L formed on the inner circumferential surface 56 as thin ice and snow fragments.

[0025] Each support arm 46, like the connecting rod 40, is preferably made of metal, is positioned perpendicular to the connecting rod 40, and both ends are bent toward the inner circumferential surface 56. The bending angle α of the tip of the support arm 46 is set to approximately 110°. The connection position and bending angle of the support arm 46 relative to the connecting rod 40 can be set as appropriate. The water spray 24 and blade 28 are positioned at a predetermined angular distance θ from each other in the circumferential direction of the fixed hollow cylinder 20. The predetermined angular distance θ can be set appropriately so that the thin ice layer L formed on the cooling surface by the water sprayed by the water spray 24 is not peeled off by the blade 28 until it reaches a certain thickness.

[0026] Each water spray nozzle 24 is positioned on the side of the rotational lag of the nearest blade 28. The installation height of the water spray nozzle 24 is preferably approximately in the middle of the height of the inner circumferential surface 56 of the fixed hollow cylinder 20 so that the spray range can cover the entire height of the inner circumferential surface 56. The spray pressure of the mist of water ejected from the water spray nozzle 24 is preferably about 0.05 to 0.2 MPa.

[0027] The water spray nozzle 24 allows for adjustment of the distance from the water spray nozzle 24 to the inner surface 56 of the inner cylinder 22, and the direction of the water sprayed from the water spray nozzle 24, depending on how it is attached to the support arm 46.

[0028] The blades 28 attached to the ends of each support arm 46 are made of rectangular metal plates having a length equivalent to the height of the inner cylinder 22 of the fixed hollow cylinder 20, and are positioned to form a predetermined inclination angle α with respect to the tangential direction in the rotational direction. A spacing adjustment bolt 29 is attached to the support arm 46 side end of the blade 28 to adjust the distance between the tip of the blade 28 and the inner circumferential surface 56 of the fixed hollow cylinder 20. The distance between the tip 27 of the blade 28 and the inner circumferential surface 56 of the inner cylinder 22 of the fixed hollow cylinder 20 is preferably about 0.1 to 0.2 mm. Due to manufacturing tolerances of the inner circumferential surface 56 of the inner cylinder 22 of the hollow cylinder 20, the minimum clearance between the inner circumferential surface 56 and the tip 27 of the blade 28 is approximately 0.1 mm, while depending on the thickness of the thin ice layer L formed on the inner circumferential surface 56, if it exceeds 0.2 mm, it becomes difficult to obtain thin ice snow fragments of the desired snow quality, such as moisture content. Regarding the relationship between the spacing and the size of the detached thin ice and snowflakes, within this range, the effect on the size of the thin ice and snowflakes, especially their thickness, is small. It has been confirmed that the size of the thin ice and snowflakes is determined by the refrigerant temperature and / or spray water temperature, flow rate, and the rotation speed of the connecting rod 40.

[0029] A water temperature and flow rate adjustment device 61 is provided to adjust the temperature and flow rate of the water supplied to the watering nozzle 24. It includes a water tank 62, a heating heater 64 for heating the water in the water tank 62, piping 66 connecting the water tank 62 and the watering nozzle 24, and a liquid transfer pump 68 installed in the middle of the piping 66. A control panel 70 controls the heating heater 64 and the liquid transfer pump 68 to adjust the water temperature and flow rate, so that the water with adjusted temperature and flow rate is supplied to the watering nozzle 24 via the piping 66. Tap water can be supplied to the thin ice snow flake manufacturing device 18, and the water temperature should be between 5 and 25°C. The refrigerant temperature control device 72 is provided to adjust the temperature of the refrigerant supplied into the hollow cylinder 20 and includes a normal refrigeration unit 74 which includes a condenser (not shown) and an inverter-controlled compressor (not shown), a return pipe 76 which returns the refrigerant from an evaporator (not shown) located inside the hollow cylinder 20 to the refrigeration unit 74 via an evaporation pressure regulating valve 80, and a supply pipe 78 which supplies the refrigerant toward the evaporator via an expansion valve 82. The control panel 70 controls the refrigeration unit 74 and the evaporation pressure regulating valve 80, controlling the temperature and flow rate of the refrigerant supplied into the hollow cylinder 20, so that the refrigerant with adjusted temperature and flow rate is supplied to the evaporator inside the hollow cylinder 20, cooling the cooling surface 22 to a predetermined temperature, and the heated refrigerant returns to the refrigeration unit 74.

[0030] The control panel 70 controls the drive motor 54 and adjusts the rotation speed of the connecting rod 40, thereby adjusting the speed at which water is supplied to the cooling surface 22 and the speed at which the thin ice layer L formed on the cooling surface 22 is peeled off. With the above configuration, the water temperature and water flow rate are adjusted by the water temperature and water flow rate adjustment device 61 according to the desired size of thin ice snowflakes and the desired production amount (snowfall amount) per hour, while the refrigerant temperature is adjusted by the refrigerant temperature adjustment device 72, and the speed at which the thin ice layer L is peeled off is adjusted by controlling the drive motor 54.

[0031] The booster airflow generator 100 includes an airflow generation drive source 102, an airflow discharge nozzle 104 that blows out the airflow J generated by the airflow generation drive source 102, and an airflow supply pipe 106 that connects the airflow generation drive source 102 and the airflow discharge nozzle 104. The airflow discharge nozzle 104 is installed in the space within the straightening cavity 312 above the upper part of the outlet side (discharge port 316) of the constricted cavity. This prevents the airflow J generated horizontally toward the vehicle V by the booster airflow generator 100 from being deflected by the airflow MF generated from inside the wind tunnel 16. The airflow generation drive source 102 may be, for example, a blower, and the airflow outlet nozzle 104 may be a plurality of nozzles, all positioned at the same level, or it may be a single nozzle with a horizontally elongated opening. The booster airflow generator 100 is positioned in the space above the outlet 316 of the constriction cavity 314 within the straightening cavity 312, and the conveyor 400 is positioned in the upstream straightening cavity 312 where the diameter is reduced. This ensures that the airflow MF within the wind tunnel 16 is not disturbed as much as possible by the booster airflow generator 100 and the conveyor 400 within the wind tunnel 16.

[0032] The booster airflow generator 100 can adjust the flow rate of the airflow J by changing the size of the booster opening and / or the booster airflow velocity according to the amount of thin ice and snow fragments per hour falling from the thin ice and snow fragment manufacturing device 18 into the wind tunnel 16 and / or the size of the thin ice and snow fragments. For example, if the amount of thin ice and snow fragments is large, the flow rate of the airflow J can be increased by adjusting the size and / or the airflow velocity of the airflow outlet nozzle 104, so that countless thin ice and snow fragments S are guided to the constriction tunnel 314 without falling and accumulating at the bottom of the straightening tunnel 312. On the other hand, the flow rate of the airflow J generated by the booster airflow generator 100 may be set according to the flow velocity of the airflow MF generated in the wind tunnel 16. For example, if the flow velocity of the airflow MF is set according to the simulated driving speed, and the flow velocity of the airflow MF is high, countless thin ice and snowflakes S may be carried by the airflow MF towards the constriction tunnel 314 even within the straightening tunnel 312. In that case, the flow rate of the airflow J generated by the booster airflow generator 100 may be lowered accordingly.

[0033] Next, the conveyor 400 is a standard one, with a drive roller 402 and a driven roller 404 spaced at a predetermined distance along the longitudinal direction of the wind tunnel 16, and the rotation axis 406 of each roller arranged horizontally in a direction perpendicular to the airflow MF generated in the wind tunnel 16, and an endless conveyor belt 408 stretched between the drive roller 402 and the driven roller 404. The rotation axis 406 of the drive roller 402 is connected to a drive motor (not shown) for example via a reduction mechanism (not shown), and the rotation direction of the rotation axis 406 is set so that the upper surface 410 of the endless conveyor belt 408 translates toward the outlet of the wind tunnel 16 along the direction of the airflow in the wind tunnel 16. The rotating shafts 406 of the drive roller 402 and the driven roller 404 are suspended and supported from the ceiling of the wind tunnel 16 by, for example, suspension rods (not shown). The upper surface 410 of the conveyor belt 408 is positioned to overlap with the position of the discharge port 32 of the thin ice and snow fragment manufacturing device 18 in the longitudinal direction of the straightening cavity 312. This ensures that the countless thin ice and snow fragments S manufactured by the thin ice and snow fragment manufacturing device 18 and naturally falling through the straightening cavity 312 from the discharge port 32 are reliably received by the upper surface 410 of the conveyor belt 408 and guided toward the constricting cavity 314.

[0034] From the viewpoint of suppressing airflow turbulence caused by the installation of the conveyor 400 inside the wind tunnel 16, it is preferable that the diameters of the drive roller 402 and the driven roller 404 be as small as possible, the drive motor is preferably installed outside the wind tunnel 16, and the suspension rods of the drive roller 402 and the driven roller 404 are preferably positioned to overlap within the cross-section of the wind tunnel 16. With the above configuration, the thin ice and snow fragments falling from the thin ice and snow fragment manufacturing device into the wind tunnel 16 are received by the upper surface 410 of the endless conveyor belt 408, translated toward the outlet 316 of the wind tunnel 16, and in the process, can be carried by the airflow MF inside the wind tunnel 16 and blown away. The total length of the endless conveyor belt 408 is not directly related to turbulence in the airflow MF inside the wind tunnel 16, since the orientation of the endless conveyor belt 408 is aligned with the longitudinal direction of the wind tunnel 16, and can be determined from this perspective. When the airflow J generated by the booster airflow generator 100 ensures that the countless thin ice and snow fragments falling from the thin ice and snow fragment manufacturing device into the wind tunnel 16 are reliably blown toward the vehicle, the conveyor 400 will run idle. However, due to the relationship between the flow rate of the airflow J and the flow rate of the countless thin ice and snow fragments S falling naturally, the conveyor 400 is designed to function as a backup in case there are thin ice and snow fragments that cannot be carried by the airflow.

[0035] The operation method of the blizzard generation system 10 having the above configuration will now be described. The temperature inside the measurement chamber 300 where the thin ice snowflake manufacturing device 18 is installed should be kept below 5°C, preferably below 3°C.

[0036] First, the desired size of thin ice and snowflakes and the desired production rate (snowfall amount) per hour are set according to the purpose of the snow environment test, and the airflow velocity of the airflow MF in the wind tunnel 16 is set according to the driving speed of the vehicle V that will be simulated. Next, the distance L from the outlet 316 of the constricted flow tunnel 314 to the test specimen S of thin ice and snowflakes is set according to the desired snowflake height range R on the vehicle V. For example, if the desired snowflake height range R on the vehicle V is low, the distance L is set to be long. Depending on the desired range of snowflake heights that thin ice and snowflakes may be blown onto the vehicle V, the distance from the outlet 316 of the constriction tunnel 314 to the vehicle V may be set and / or the airflow rate of the booster airflow generator 100 may be adjusted. Alternatively, in the booster airflow generator 100, the size of the booster opening and / or the booster airflow velocity may be adjusted according to the height of the snow flying at the outlet 316. Alternatively, the airflow rate from the booster airflow generator 100 may be set according to the flow velocity of the airflow MF generated in the wind tunnel 16. Next, based on the set desired size of thin ice snowflakes and the desired production rate (snowfall) per hour, the control panel 70 controls the water temperature and flow rate adjustment device 60, the refrigerant temperature adjustment device 72, and the drive motor 54 to adjust the temperature and flow rate of the water supplied to the water spray nozzle 24, the refrigerant temperature, and the rotation speed of the connecting rod 40. More specifically, the refrigerator 74 is activated to supply refrigerant to the fixed hollow cylinder 20 via pipes 76 and 78, raising the temperature of the inner surface of the fixed hollow cylinder 20 to -10 to -20°C, while the amount of water sprayed from the water sprayer 24 and the rotation speed of the connecting rod 40 are set according to the size and amount of thin ice and snow fragments produced.

[0037] The mist of water sprayed from the water sprayer 24, which rotates counterclockwise with the support arm 46, toward the inner surface of the fixed hollow cylinder 20, instantly freezes upon contact with the inner surface of the fixed hollow cylinder 20, forming a thin layer of ice L. The thin layer of ice L formed on the inner surface of the fixed hollow cylinder 20 is peeled off by the blade 28, which rotates counterclockwise with the support arm 46, into thin ice and snow fragments. The countless peeled-off thin ice and snow fragments fall from the discharge port 32 into the straightening cavity 312.

[0038] Next, the booster airflow generator 100 directs an airflow J horizontally towards the stationary vehicle V, between the discharge port 32 and the contraction cylinder 314, so that snow falls from directly above the stationary vehicle V, towards the thin ice and snowflakes S falling by gravity from the discharge port 32. For example, if the amount of thin ice and snow fragments produced by the thin ice and snow fragment manufacturing device 18 is large and the desired level of blizzard blowing onto the stationary vehicle V is high, it is advisable to increase the flow rate of the airflow J from the booster airflow generator 100 so that countless thin ice and snow fragments are carried by the airflow J from the booster airflow generator 100 and blown away before they fall to the upper surface 410 of the conveyor 400, or before they are guided toward the constriction cylinder 314 at the upper surface 410 of the conveyor 400. For example, if the simulated speed of the stationary vehicle V is high, and accordingly the flow velocity of the airflow MF generated in the wind tunnel 16 is high, there is a high probability that countless thin ice and snow fragments will be carried by the airflow MF towards the constricted cavity 314 within the straightening cavity. In such a case, the conveyor 400 can be kept running to prevent fluctuations in the snow-drifting state due to changes in the opening between the ceiling of the straightening cavity 312 and the conveyor 400 over time due to snow accumulation, while the flow rate of the airflow J from the booster airflow generator 100 can be reduced. For example, if the simulated speed of the stationary vehicle V is low, and accordingly the flow velocity of the airflow MF generated in the wind tunnel 16 is low, but the desired level of snow blowing onto the stationary vehicle V is low, the flow rate of the airflow J from the booster airflow generator 100 can be increased, and the distance to the constricted flow tunnel 314 can be adjusted by moving the stationary vehicle V, or the position of the thin ice snowflake manufacturing device 18 can be moved. For example, if moving the thin ice and snowflake manufacturing device 18 alone, or adjusting the flow rate of the airflow J by the booster airflow generator 100 alone, is insufficient, a combination of moving the thin ice and snowflake manufacturing device 18 and adjusting the flow rate of the airflow J by the booster airflow generator 100 may be used.

[0039] With the snowfall system having the above configuration, it is possible to simulate driving by directing the airflow MF generated in the wind tunnel 16 by the wind tunnel equipment 11 from the constricted flow tunnel toward the stationary vehicle V. In this process, the thin ice and snowflake manufacturing device 18 is installed at the top of the straightening tunnel, and the water spray 24 and blade 28 are rotated concentrically with the fixed hollow cylinder by the rotational drive means 30. By spraying water with the water spray 24 toward the inner cooling surface of the fixed hollow cylinder 20, a thin ice layer L is formed on the inner cooling surface. At the same time, the thin ice layer L is peeled off by the blade 28, which is spaced at a predetermined angular interval from the water spray 24 in the circumferential direction of the fixed hollow cylinder 20, thereby generating thin ice and snowflakes. The generated thin ice and snowflakes are then allowed to fall naturally from the discharge port 32 at the lower end, making it possible to carry the thin ice and snowflakes on the airflow MF generated in the wind tunnel 16 and blow them toward the stationary vehicle V. In contrast to conventional blizzard simulations using artificial snow made from ice particles, which have difficulty reproducing snow accumulation conditions similar to those in nature on simulated vehicles, the present invention utilizes the airflow generated by the booster airflow generator 100 to guide thin ice and snow fragments S that naturally fall into the wind tunnel 16 from the thin ice and snow fragment manufacturing device 18 to the outlet 316 of the constricted flow cavity 314 where the airflow velocity of the airflow MF generated in the wind tunnel 16 increases. The fragments are then carried by the airflow MF generated in the wind tunnel 16 and blown out from the outlet 316 of the constricted flow cavity 314. This makes it possible to smoothly conduct tests in which a blizzard of thin ice and snow fragments S is blown onto a stationary vehicle V at a desired level and height range while simulating driving using the stationary vehicle V.

[0040] Although embodiments of the present invention have been described in detail above, various modifications and changes are possible for those skilled in the art without departing from the scope of the present invention. For example, although this embodiment has been described as using a booster airflow generator 100 and a conveyor 400, it is not limited to this. If the simulated travel speed is high and the airflow velocity in the straightening tunnel is correspondingly high enough to guide the thin ice and snow fragments that naturally fall from the thin ice and snow fragment manufacturing device into the wind tunnel 16, the conveyor 400 may be omitted and the booster airflow generator 100 alone may be used. When using the wind tunnel as a normal wind tunnel without snow, the booster airflow generator 100 and conveyor 400 can be moved outside the wind tunnel.

[0041] For example, in this embodiment, the conveyor 400 used with the booster airflow generator 100 has been described as having a fixed height, but it is not limited to this. The level of the conveyor 400 in the rectifying tunnel can be adjusted, thereby adjusting the height range of the thin ice and snowflakes guided by the airflow generated by the booster airflow generator 100. For example, in this embodiment, the booster airflow generator 100 and the conveyor 400 are used to fix the position of the thin ice and snowflake manufacturing device and adjust the airflow velocity provided by the booster airflow generator 100. However, the invention is not limited to this, and the booster airflow generator 100 and the conveyor 400 may be used to adjust the airflow velocity provided by the booster airflow generator 100 while simultaneously adjusting the level of the conveyor 400 and moving the position of the thin ice and snowflake manufacturing device. [Brief explanation of the drawing]

[0042] [Figure 1] This is an overall configuration diagram of a blizzard generation system according to an embodiment of the present invention. [Figure 2] This is a partial diagram showing the snow-throwing conditions on a stationary vehicle V of a blizzard generation system according to an embodiment of the present invention. [Figure 3] This is a schematic side view showing a thin ice snowflake manufacturing apparatus 18 of a blizzard generation system according to an embodiment of the present invention. [Figure 4] This is a schematic plan view showing a thin ice snowflake manufacturing apparatus 18 of a blizzard generation system according to an embodiment of the present invention. [Explanation of symbols]

[0043] S Thin ice flakes MF airflow J Airflow R Desired snowfall height range V Stationary Vehicles θ predetermined angular interval α blade tilt angle w width of the circumferential groove 60 d Depth of the circumferential groove 60 L Thin ice layer 10 Blizzard generation system 11 Wind tunnel equipment 16 Wind tunnel 18. Thin ice and snowflake manufacturing device 20 Fixed hollow cylinder 21 Hollow part 24 Watering spray 27 Tip 28 blades 29 Fixing bolts 30 Rotary drive means 32 Outlet 40 connecting rods 42 End 44. Rotating rod mechanism 46 Support Arm 48 tires 50 Vertical Rotating Shaft 52 Rotating shaft support section 54 Rotary drive unit 56 Inner surface 58 Outer surface 60 Circumferential grooves 61 Water temperature water adjustment device 62 water tanks 64 Heating heater 66 Piping 68 Liquid transfer pump 70 Control Panel 72 Refrigerant temperature adjustment device 74 Refrigeration unit 76 Return pipe 78 Supply pipe 80 Flow control valve 100 Booster Airflow Generator 102 Airflow generation drive source 104 Airflow Nozzle 106 Airflow supply pipe 300 Measurement room 302, 304, 306, 308 Bent torso 310 Second Diffusion Body 306 Third Bent Torso 308 Fourth Bent Torso 312 Rectifier Cylinder 314 Shrink-flow body 316 Air outlet 317 Receiving Port 400 Conveyor 402 Drive roller 404 Driven roller 406 Drive Rotating Shaft 406 Driven rotating shaft 408 Conveyor Belt 410 Top

Claims

1. A wind tunnel system that directs the airflow generated inside the wind tunnel towards the test specimen through a straightening tunnel and a constricting tunnel, It has a thin ice and snowflake manufacturing device installed at the top of the flow straightening tunnel, The thin ice and snow flake manufacturing apparatus includes a water spray sprayer that sprays water toward the inner cooling surface of a fixed cylinder, A blade whose tip is separated from the inner cooling surface at a predetermined distance, The device comprises a water spray nozzle and a rotational drive means for rotating the nozzle and the blade concentrically with the fixed cylinder, The water sprayer and the blade are spaced apart from each other at a predetermined angular distance in the circumferential direction of the fixed cylinder. An outlet is provided at the lower end, facing the wind tunnel, to allow the thin ice and snow fragments generated by peeling off the thin ice layer formed on the inner cooling surface with the blade to fall naturally. Furthermore, the blizzard generation system is characterized by having a booster airflow generator that carries the thin ice and snow fragments that naturally fall into the wind tunnel from the thin ice and snow fragment manufacturing device onto the airflow generated in the wind tunnel and blows them out from the outlet of the constricted flow tunnel.

2. The blizzard generation system according to claim 1, comprising a plurality of thin ice and snowflake manufacturing devices, wherein the horizontal position of each thin ice and snowflake manufacturing device can be adjusted independently on a flow straightening cavity.

3. Furthermore, the blizzard generation system according to claim 1, further comprising a conveyor within the wind tunnel that guides thin ice and snow fragments falling from the thin ice and snow fragment manufacturing apparatus toward the constricted flow tunnel, the conveyor comprising a drive roller and a driven roller arranged horizontally at a predetermined distance from each other in the direction of airflow within the wind tunnel, with their respective axis of rotation perpendicular to the direction of airflow within the wind tunnel, a conveyor belt stretched between the drive roller and the driven roller, and a rotational drive means for rotationally driving the axis of rotation of the drive roller so that the upper side of the conveyor belt is translated in the direction of airflow within the wind tunnel.

4. The blizzard generation system according to claim 3, wherein the upper surface of the conveyor belt is positioned to overlap with the discharge port position of the thin ice and snowflake manufacturing apparatus in the longitudinal direction of the straightening cavity.

5. The blizzard generation system according to claim 1, wherein the airflow outlet nozzle of the booster airflow generator is located in the space above the top of the outlet of the constriction cavity within the straightening cavity.

6. The blizzard generation system according to claim 1, wherein the booster airflow generating device adjusts the size of the booster opening and / or the booster airflow velocity according to the height of the snow flying at the outlet.

7. A method for generating a snowstorm, in which the airflow rate from the booster airflow generator is set according to the flow velocity of the airflow generated in the wind tunnel, in the snowstorm generation system according to claim 6.

8. A method for generating a blizzard according to claim 1, wherein the distance from the outlet of the constricted flow cavity to the test specimen is set and / or the airflow rate of the booster airflow generator is adjusted according to a desired range of snowflake heights on the test specimen.

9. The blizzard generation system according to claim 1, wherein the thin ice snowflake manufacturing device is provided in the upper part of the straightening tunnel, is fitted onto a rail provided in the upper part of the straightening tunnel and extending along the direction of the wind tunnel, and is movable together with the frame between the straightening tunnel and a stationary vehicle.

10. The blizzard generation system according to claim 1, wherein the booster airflow generating device comprises an airflow generating drive source, an airflow blowing nozzle for blowing out the airflow generated by the airflow generating drive source, and an airflow supply pipe connecting the airflow generating drive source and the airflow blowing nozzle, and the airflow blowing nozzle is directed in the direction of the airflow generated in the wind tunnel.

11. The blizzard generation system according to claim 1, wherein the wind tunnel is of the recirculating type, the outlet and inlet of the constricted flow tunnel are arranged opposite each other, and a stationary vehicle is positioned between the outlet and the inlet.

12. The blizzard generating system according to any one of claims 1 to 11, wherein the thickness of the thin ice and snowflakes is 0.1 mm to 0.2 mm so that they can be carried away by the wind.

13. The blizzard generation system according to claim 6, wherein the booster airflow generating device adjusts the airflow rate by changing the size of the booster opening and / or the booster airflow velocity according to the amount of thin ice and snow fragments per hour and / or the size of the thin ice and snow fragments that fall into the wind tunnel from the thin ice and snow fragment manufacturing device.

Images