Method of flying snow by thin snowflakes

Abstract

To provide a snow scattering method capable of performing a precise snow environment test by scattering snow to a specimen by utilizing artificial snow close to the properties of natural snow.SOLUTION: A method for flying artificial snow toward a test piece by placing the artificial snow on an air flow from behind, the method comprising the steps of: adjusting a temperature or humidity of the air flow in accordance with a moisture content required for the artificial snow; and placing the artificial snow on the air flow adjusted in temperature or humidity.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for blowing snow using thin snow flakes, and more specifically to a method for blowing snow using thin snow flakes that enables precise snow environment testing by using artificial snow that has properties similar to those of natural snow to blow snow onto a test specimen. [Background technology]

[0002] BACKGROUND ART Conventionally, environmental tests have been carried out for various purposes in which airflow generated in a wind tunnel is blown toward a test specimen to simulate running conditions. One example is an environmental test in which artificial snow with a predetermined moisture content is carried by an air current and blown toward a test specimen, such as a stationary vehicle, to evaluate the effect of snow on the test specimen. They are divided into types depending on the artificial snow used.

[0003] For example, Patent Document 1 discloses a snowstorm generating system that uses artificial snow made from crushed ice particles. In this snowstorm generating system, ice pieces produced by an ice maker are crushed by an ice crusher to form ice particles of a predetermined size, which are then pressure-fed by the airflow through a snow supply pipe, branched by a distributor into multiple branch pipes, and converted into wet snow with a predetermined moisture content by a snow-wetter device in each branch pipe, and reach the blowout nozzle in the wind tunnel. The snow blown out from the nozzle outlet is carried by the airflow and flows as a snowstorm along the direction of the airflow. The snowstorm strikes a diffusion surface located outside the nozzle and at a predetermined position ahead of the airflow in the direction of the airflow, facing the nozzle. The diffusion surface is made of a material that is resistant to snow adhesion and has a conical shape with its apex facing the nozzle, so that the snowstorm does not adhere to the diffusion surface. Instead, the snowstorm is guided along the diffusion surface and diffuses outward in all directions, preventing fluctuations in diffusion characteristics over time due to adhesion to the diffusion surface. Such a snowstorm generating system can, to some extent, spread the snowstorm to a desired spreading area.

[0004] In this regard, Patent Document 2 discloses a method for making artificial snow from ice particles into wet snow. This method of producing wet snow includes the steps of: transporting dry snow toward the outlet opening on a carrying airflow within the flow path at a speed greater than a predetermined speed; supplying hot air of a predetermined temperature and humidity into the flow path from around the outer periphery of the flow path upstream of the outlet opening; uniformly mixing the carrying airflow, dry snow, and hot air within the flow path to create an atmosphere of a uniform temperature sufficient to melt the dry snow within the flow path; and exchanging heat between the carrying airflow, dry snow, and hot air within this atmosphere until it reaches the outlet opening.As a result, the dry snow is transported on the carrying airflow, melted, and turned into wet snow, and the wet snow is blown out from the outlet opening.

[0005] According to the method for generating wet snow having the above configuration, when dry snow is transported toward the outlet opening on a transport airflow at a predetermined speed or above within the flow path, hot air of a predetermined temperature and humidity is supplied into the flow path from around the outer surface of the flow path upstream of the outlet opening, causing the transport airflow, dry snow, and hot air to mix uniformly within the flow path, creating an atmosphere of a uniform temperature sufficient to melt the dry snow within the flow path, and heat exchange occurs between the transport airflow, dry snow, and hot air within the created atmosphere up to the outlet opening, resulting in the creation of an atmosphere of a uniform temperature sufficient to melt the dry snow within the flow path, melting each dry snow into wet snow, and allowing the wet snow to be efficiently blown out from the outlet opening without adhering to the inner surface of the flow path.

[0006] However, with this method and device for generating wet snow, artificial snow in the form of granular ice, which has properties different from those of natural snow, is simply melted using hot air while being transported through a transport pipe into the wind tunnel, and the resulting snow is then blown toward the test specimen by the air current in the wind tunnel from behind, resulting in the following technical problems: first, a separate device for generating wet snow is required; and second, it is difficult to adjust the ambient temperature of the test specimen.

[0007] In this regard, Patent Document 3 discloses a method and device for generating snowflakes that are closer to the properties of natural snow than artificial snow made of ice particles. This snowflake generating method comprises the steps of setting a predetermined ambient temperature or humidity where a carrier is placed, transporting pre-made snow particles toward the carrier, capturing the transported snow particles on the surface of the carrier and allowing them to adhere to and grow on the carrier surface to generate snowflakes, and peeling the generated snowflakes from the carrier surface. This snowflake generating device is placed in a testing room where tests are conducted using artificial snow, and comprises a transporting means for transporting pre-made snow particles toward the carrier, a carrier means for capturing the transported snow particles and allowing them to adhere to and grow on the carrier surface to generate snowflakes, a peeling means for peeling the generated snowflakes from the carrier, and an ambient temperature or humidity adjusting device for setting a predetermined ambient temperature or humidity where the carrier is placed.

[0008] According to the method for generating snowflakes having the above-mentioned configuration, instead of using the snowflakes as they are, the ambient temperature or humidity where the carrier is placed is set to a predetermined value, and the previously generated snowflakes are transported toward the carrier, where they are captured on the surface of the carrier and allowed to adhere and grow on the carrier surface to generate snowflakes.The generated snowflakes are then detached from the carrier surface, and the generated snowflakes are turned into snowflakes.For example, when making snowflakes detached from the carrier surface fall, it is possible to change the size of the snowflakes that fall, or to separate the snowmaking process from the snowfall process, so that snow can fall in an environment (temperature conditions, humidity conditions) different from the snowmaking environment, and the snow can be made wet during snowfall.In general, it is possible to change the quality of snow as desired.

[0009] However, this type of snowflake generation method and device merely allows large snowflakes, which differ in properties from natural snow, to adhere to and grow on a carrier surface, and then simulate snowfall toward a test object using the resulting large snowflakes, which can even turn into wet snow during the snowfall. However, this method has two technical problems: first, it cannot be used for snowstorm tests using airflow in a wind tunnel, and second, it is difficult to control the ambient temperature of the test object. In particular, for electric vehicles, where the battery is located under the vehicle and generates heat while driving, the snow accumulation conditions fluctuate depending on the temperature difference between the battery and the ambient temperature of the vehicle, so it is important to simulate the ambient temperature of the vehicle. As described above, until now, no method for blowing artificial snow has been developed that uses artificial snow that has properties similar to those of natural snow, including its moisture content, and that is flexible enough to enable various environmental tests on various test specimens.

[0010] In this regard, Patent Document 4 discloses that artificial snow in the form of ice particles is made by crushing flake ice pieces made by a reamer-type ice-making device, and the ice pieces are carried by an air current from behind in a wind tunnel and blown toward a test specimen.The moisture content of the flake ice pieces is adjusted by adjusting the evaporation temperature of the refrigerant, the water temperature, and the rotation speed of the reamer in the reamer-type ice-making device. However, when water is supplied to a cooling surface cooled by a refrigerant and the thin ice layer that forms is peeled off with a reamer blade to separate the ice flakes, if the water content of the ice flakes is high, the thin ice layer will not separate well from the cooling surface, making it difficult to test using artificial snow with the desired water content. [Patent Document 1] Patent Publication No. 2015-143583 [Patent Document 2] Patent Publication No. 2016-042020 [Patent Document 3] Patent No. 6763792 [Patent Document 4] Patent No. 5843247 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0011] In view of the above technical problems, the object of the present invention is to provide a snow-flying method that uses artificial snow that has properties similar to those of natural snow, including its moisture content, and that allows for precise snow environment testing, including adjustment of the ambient temperature of the test specimen, by flying the snow onto the test specimen. In view of the above technical problems, the object of the present invention is to provide a snow flying method that uses artificial snow that has properties similar to those of natural snow, including its moisture content, and that can be blown onto various types of test specimens, thereby enabling various sophisticated snow accretion evaluation tests, such as snowstorm tests and snowfall tests. [Means for solving the problem]

[0012] In order to achieve the above object, the snow flying method of the present invention comprises: This method involves placing artificial snow on an air current from behind and blowing it towards a test specimen, and includes a step of adjusting the temperature or humidity of the air current according to the moisture content required for the artificial snow, and placing the artificial snow on the temperature- or humidity-adjusted air current.

[0013] According to the snow flying method configured as described above, when artificial snow is carried by an air current from behind and blown toward the test specimen, the temperature or humidity of the air current is adjusted according to the moisture content required for the artificial snow. By carrying the artificial snow toward the test specimen on an air current with adjusted temperature or humidity, artificial snow with the desired moisture content can be used. By using artificial snow with properties similar to those of natural snow and blowing it toward the test specimen, precise snow environment testing becomes possible.

[0014] In addition, when artificial snow is carried by parallel air currents generated in the wind tunnel and blown toward a test specimen downstream outside the wind tunnel, the method may include a step of adjusting the temperature and / or humidity of the air current according to the required ambient temperature of the test specimen, and carrying the artificial snow on the temperature- and / or humidity-adjusted air current. Furthermore, when artificial snow is carried by parallel air currents generated in the wind tunnel and blown toward a test specimen downstream outside the wind tunnel, the method may include a step of adjusting the temperature and / or humidity of the air current depending on the length of time the artificial snow is in contact with the air current before reaching the test specimen, and carrying the artificial snow on the temperature- and / or humidity-adjusted air current. Furthermore, when artificial snow is carried by parallel air currents generated in a wind tunnel and blown toward a test specimen downstream outside the wind tunnel, the method may include a step of adjusting the temperature and / or humidity of the air current depending on the air current speed and / or the distance from the point where the artificial snow starts to come into contact with the air current in the wind tunnel to the test specimen, and carrying the artificial snow on the temperature- and / or humidity-adjusted air current. Furthermore, a step of setting the amount of artificial snow produced per hour and the quality of the snow made of thin snow flakes according to an environmental test using snow blown onto a test specimen; producing thin snow flakes of a predetermined production amount and a predetermined snow quality per hour at a level above the outlet of the wind tunnel; A step of allowing the produced thin snowflakes to fall naturally into a wind tunnel or between the outlet of the wind tunnel and the test piece; A step of making naturally falling thin snowflakes fly toward the test specimen on an air current from the upstream side of the test specimen toward the test specimen; The method may further comprise a step of determining a set temperature or humidity of the airflow depending on the distance between the falling position of the snowflakes and the specimen. Furthermore, the method may include a step of allowing the manufactured thin snow flakes to fall naturally between the outlet of the wind tunnel and the test piece, and a step of allowing the naturally falling thin snow flakes to fall from above the test piece by being carried by the air current that flows from the upstream side of the test piece toward the test piece.

[0015] In addition, the snowfall stage may involve directing the airflow from the upstream side of the test piece toward the test piece diagonally upward from a dedicated airflow outlet for snowfall that is provided separately from the air outlet, so that naturally falling thin snow flakes are carried on the diagonally upward airflow and caused to fall from above the test piece. It is also preferable to have a step of allowing the produced flakes of snow to fall naturally into the wind tunnel, and a step of letting the naturally falling flakes of snow fall on the air current flowing toward the outlet in the wind tunnel and blowing them as a blizzard toward the test specimen. Furthermore, it is preferable to have a step of simulating natural wind on the test specimen by the air current flowing from the upstream side of the test specimen toward the test specimen after snow has accumulated on the test specimen. Furthermore, the step of producing the thin ice snowflakes may preferably involve spraying water on the cooling surface to form a thin ice layer, peeling off the formed thin ice layer, and allowing it to fall naturally.

[0016] In addition, in the manufacturing stage of the thin snowflakes, it is preferable to set a maximum moisture content according to the required size, adjust the temperature of the airflow according to the difference between the required moisture content of the thin snowflakes and the maximum moisture content, and place the artificial snow on the temperature-adjusted airflow. In addition, in the manufacturing stage of the thin snow flakes, it is preferable to set a maximum moisture content according to the required production amount, adjust the temperature of the airflow according to the difference between the required moisture content of the thin snow flakes and the maximum moisture content, and place the artificial snow on the temperature-adjusted airflow. Furthermore, it is advisable to set the temperature of the airflow according to the required ambient temperature of the test specimen, and adjust the moisture content of the snowflakes during the manufacturing stage according to the difference between the required moisture content of the snowflakes and the moisture content of the snowflakes determined according to the set airflow temperature. Furthermore, when setting the temperature of the airflow according to the required ambient temperature of the test specimen, it is advisable to set the temperature of the airflow taking into account temperature fluctuations in the airflow caused by heat exchange between the airflow and the thin snowflakes supplied during the thin snowflake production stage.

[0017] Additionally, the thickness of the snowflakes may be 0.1 to 0.2 mm, and the length may be 1 to 20 mm. In addition, an environmental test in which snow is blown onto a test specimen using a wind tunnel having, in that order, a flow straightening tunnel that directs airflow generated upstream from an outlet toward the test specimen and a flow contraction tunnel also having an outlet, may include steps of positioning the height at which the thin snowflakes begin to fall naturally above the vehicle, adjusting the natural fall position between the flow straightening tunnel and the vehicle, and adjusting the airflow speed in the wind tunnel, and the airflow temperature or airflow humidity, depending on whether the test is a snowstorm simulation test on a moving simulation vehicle, a snowfall simulation test on a traffic jam simulation vehicle, or a natural wind simulation test on a snow-covered vehicle. Furthermore, the free-fall of the thin snowflakes may be carried out in a tunnel, and the free-fall start height of the thin snowflakes may be positioned above the tunnel and the vehicle. BEST MODE FOR CARRYING OUT THE INVENTION

[0018] An embodiment of a snow-flying system used in the snow-flying method using thin snow flakes of the present invention will be described in detail below with reference to the drawings. As shown in Figures 1 and 2, the flying snow system 10 uses artificial snow made of thin snow flakes, and is configured to simulate flying snow by carrying the artificial snow on an air current behind it and moving it toward the test specimen, the vehicle V. To this end, the system includes a wind tunnel facility 16 and a thin snow flake manufacturing device 18. In particular, when continuously supplying the required amount of flying snow having a specified snow quality, the main influencing factors of which are the size and moisture content of the flakes, toward vehicle V, it is required to quickly supply the flakes to be used as artificial snow while producing them during testing under specified temperature and humidity control so that the flakes can be spread over the entire height of vehicle V and, in some cases, achieve the desired distribution of flying snow concentration along the height of vehicle V.

[0019] In summary, the snow flying system 10 generates an airflow MF toward the vehicle V in a wind tunnel 16, while producing artificial snow in the form of thin snow flakes using a thin snow flake manufacturing device 18, and the falling thin snow flakes fly toward the vehicle V, simulating, for example, a snowstorm while the vehicle is moving.

[0020] The wind tunnel 16 is an open, circulating type, and is formed in a generally rectangular shape in plan view, and includes a measurement chamber 300 in which a vehicle V to be measured is placed, and first to fourth curved bodies 302, 304, 306, 308. The airflow MF generated by the blower 25 passes through the second diffusion drum 310, the third curved drum 306, the fourth curved drum 308, the flow straightening drum 312, and the contraction drum 314, and flows 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 arranged opposite each other through the measurement chamber 300, and the air flows through the receiving port 317, the first curved drum 302, and the second curved drum 304 in that order. The airflow MF blown by the blower 25 first reduces the wind speed (dynamic pressure) of the entire airflow, increasing the pressure (static pressure) in the intermediate body, and then passes through the contraction body 314, so that the airflow MF with a volume (wind speed) necessary and sufficient for measurement can be blown out from the outlet 316 into the measurement chamber 300.

[0021] As will be explained later, the thin snowflakes are supplied as flying snow toward the vehicle V in the temperature- or humidity-controlled airflow MF behind the measurement chamber 300, and by adjusting the wind speed of the airflow MF using the blower 25, it is possible to simulate a moving vehicle V even though the vehicle V is stationary. In addition, in the case of a recirculating wind tunnel 16 for snowfall testing, a separate snow repair device 38 is provided downstream of the vehicle V to separate and collect the snow after the test.In any case, in order to separate the snow by the gravity of the snow falling or the inertial effect, an area is provided downstream of the vehicle V where the airflow MF is not straightened.

[0022] Next, as shown in Figures 3 and 4, the thin ice snowflake manufacturing device 18 has a water spray spray 24 that sprays water toward the inner surface 56 of the fixed hollow cylinder 20, a blade 28 whose tip 26 is spaced a predetermined distance from the inner surface 56, and a rotational drive means 30 that rotates the water spray spray 24 and the blade 28 concentrically with the fixed hollow cylinder 20, and the water spray spray 24 and the blade 28 are spaced a predetermined angular distance θ from each other in the circumferential direction of the fixed hollow cylinder 20, and an outlet 32 ​​is provided at the lower end through which the thin ice snowflakes S generated by peeling off the thin ice layer L formed on the inner surface 56 with the blade 28 fall naturally.

[0023] The thin ice and snow flake manufacturing device 18 is fixed to the ceiling of a stand (not shown), and the thin ice and snow flakes made by the thin ice and snow flake manufacturing device 18 fall into the wind tunnel 16 or the measurement chamber 300 through an opening on the underside of the stand. The thin snowflake manufacturing device 18 can be moved between the flow straightening cavern 312 and the stationary vehicle V depending on the content of the environmental test using flying snow on the stationary vehicle V. For example, when the airflow from the upstream side of the stationary vehicle V toward the stationary vehicle V is directed diagonally upward from a dedicated snowfall airflow outlet, and the naturally falling thin ice and snow flakes are made to fall from above the stationary vehicle V on the diagonally upward airflow, the thin ice and snow flakes made can be positioned between the outlet 316 of the wind tunnel 16 and the stationary vehicle V at a position where they can fall naturally as they are; when the airflow inside the wind tunnel 16 is flowing toward the outlet 316, and the naturally falling thin ice and snow flakes are blown toward the stationary vehicle V as a snowstorm, the thin ice and snow flake making device 18 can be positioned at a position where the made thin ice and snow flakes can fall naturally as they are into the wind tunnel 16. In addition to using the airflow MF in the wind tunnel 16 to simulate the running of a stationary vehicle V, it can also be used in tests to simulate natural wind on a stationary vehicle V by flowing the airflow toward the outlet 316 in the wind tunnel 16 after snow has accumulated on the stationary vehicle V. When it is desired to change the snow accumulation height on a stationary vehicle V, particularly when testing while placing the vehicle on top of a dynamo roller and rotating the tires, the vehicle position is limited and the snow accumulation height position cannot be adjusted by moving the vehicle itself back and forth, so it is effective to make the thin ice snowflake manufacturing device 18 itself movable. To allow the thin ice and snow flake manufacturing device 18 to move between the tunnel 312 and the stationary vehicle V, the device 18 can be hung or mounted on the ceiling of a frame, allowing the frame to move in the direction of extension of the wind tunnel 16, or the device 18 can be fitted to rails on the ceiling of the test room to make it movable. By mounting the device 18 on rails on the ceiling of the test room so that it can move in the direction of the airflow in the wind tunnel 16 and in directions perpendicular to the airflow direction (including up, down, left, and right), the snow accumulation area can be adjusted up, down, left, and right. As a variant, a stand may be constructed to surround the outlet 316 of the wind tunnel 16, the thin ice snowflake device 18 may be installed on the stand, and the stand may be constructed as a mobile stand with casters on the bottom.

[0024] The fixed hollow cylinder 20 has an inner cylinder 22 on whose inner surface a thin ice layer L is formed, and an outer cylinder 23 surrounding the inner cylinder 22. The inner cylinder 22 and outer cylinder 23 are made of steel, and a hollow section 21 is provided between the inner cylinder 22 and outer cylinder 23. A refrigerant is supplied to the hollow section 21 from the refrigerator section 74 via pipes 76 and 78, and the inner circumferential surface 56 of the inner cylinder 22 is cooled to a predetermined temperature by the refrigerant, so that it functions as a cooling surface for spraying water. The outer circumferential surface of the fixed hollow cylinder 20 is covered with a cylindrical protective cover (not shown). The fixed hollow cylinder 20 has an outlet 32 ​​at its lower end 42 through which thin ice snowflakes S formed by peeling off the thin ice layer L formed on the inner surface 56 of the inner cylinder 22 with a blade 28 fall naturally.

[0025] A connecting rod 40 is installed horizontally so as to cross the space within the fixed hollow cylinder 20, passing through the center of the fixed hollow cylinder 20, and a connecting rod rotation mechanism 44 is installed at each end 42. A pair of blades 28 - water spray sprayers 24 are installed via support arms 46 near the center of the fixed hollow cylinder 20 at each end 42 of the connecting rod rotation mechanism 44, and the connecting rod 40 rotates around the center of the fixed hollow cylinder 20 by the connecting rod rotation mechanism 44, thereby allowing each pair of blades 28 - water spray sprayers 24 to move circumferentially around the fixed hollow cylinder 20. The level of the connecting rod 40 relative to the fixed hollow cylinder 20 may be determined as appropriate, but as will be explained later, the upper part of the fixed hollow cylinder 20 is preferred in terms of the installation mode of the connecting rod rotation mechanism 44.

[0026] The connecting rod rotation mechanism 44 provided at each end 42 is common, so only one will be explained. The connecting rod rotation mechanism 44 generally includes a pair of tires 48I, 48O arranged on both sides of the connecting rod 40, a vertical rotating shaft 50 that supports each of the pair of tires 48I, 48O so that they can rotate around the center of the tire 48, a rotating shaft support portion 52 that supports the vertical rotating shaft 50, and a drive motor 30 that drives the tires 48 to rotate. The pair of tires 48I, 48O are respectively provided on the inner circumferential surface 56 side and the outer circumferential surface 58 side of the inner tube 22 of the fixed hollow cylinder 20, and are arranged to fit into circumferential grooves 60 provided on the inner circumferential surface 56 side and the outer circumferential surface 58 side, sandwiching the fixed hollow cylinder 20 between the pair of tires 48I, 48O. The distance between the pair of tires 48I, 48O, i.e., the length of the rectangular member (described later), may be determined from the viewpoint of enabling the connecting rod 40, and thus the two sets of blades 28-water spray 24, to 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 having elasticity that provides shock absorption and deformability. More specifically, the width w of the circumferential groove 60 is set according to the width of the tire 48, and is 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 preferably determined from the perspective of being able to support the connecting rod 40 and two sets of blades 28 - water spray spray 24 with a total of four tires 48.

[0027] The rotary shaft support part 52 is, for example, a rectangular member having a central support part for each tire 48 at each of its four corners, and is arranged from above the fixed hollow cylinder 20 so as to straddle the upper circumferential surface of the fixed hollow cylinder 20 from inside to outside, and is connected to the corresponding end part 42 of the connecting rod 40 on the inner circumferential surface 56 side. As a result, the connecting rod 40 and the rotary shaft support part 52, and thus each tire 48 supported by the rotary shaft support part 52, can move as a unit. The drive motor 30 may be, for example, a drive motor, and is directly coupled to the vertical rotating shaft 50 of one of the four tires 48, forming the rotation driving tire 48, with the other tires 48 configured as driven tires 48. Note that a drive motor 30 may be provided on one tire 48 on either side of the pair of connecting rod rotation mechanisms 44, leaving a total of seven remaining tires 48 as driven tires 48. In this case, the driven tire 48 is free to rotate with respect to the corresponding vertical rotating shaft 50, and the drive tire 48 is preferably coupled to the vertical rotating shaft 50 that is rotationally driven by the drive motor 30, for example, via a reduction mechanism (not shown).

[0028] With the above configuration, the connecting rod rotation mechanism 44 supports the connecting rod 40 and the rotating shaft support part 52, and thus the tire 48 supported by the rotating shaft support part 52, and the drive motor 30 rotates the connecting rod 40, and thus the two sets of blades 28 - water spray sprayers 24, in the circumferential direction of the fixed hollow cylinder 20.As will be explained later, the water spray sprayers 24 spray water onto the inner surface 56 of the inner tube 22 of the fixed hollow cylinder 20, and the thin ice layer L formed on the inner surface 56 is peeled off as thin ice snowflakes by the blades 28.

[0029] Like the connecting rod 40, each support arm 46 is preferably made of metal, is disposed perpendicular to the connecting rod 40, and both ends are bent toward the inner peripheral surface 56. The bending angle α of the ends of the support arms 46 is approximately 110°. The connection position and bending angle of the support arms 46 relative to the connecting rod 40 may be set appropriately. The water spray spray 24 and the blade 28 are spaced apart from each other at a predetermined angular interval θ in the circumferential direction of the fixed hollow cylinder 20, and the predetermined angular interval θ can be set appropriately because the thin ice layer L formed on the cooling surface by the water sprayed by the water spray spray 24 will not be peeled off by the blade 28 until it reaches a certain thickness.

[0030] Each sprinkle spray 24 is disposed on the lagging side in the rotational direction of the nearest blade 28. The installation height of the sprinkle spray 24 is preferably set at approximately the middle position of the height of the inner circumferential surface 56 so that the spray range can cover the entire height of the inner circumferential surface 56 of the inner tube 22 of the fixed hollow cylinder 20. The spray pressure of the mist water sprayed from the sprinkle spray 24 is preferably about 0.05 to 0.2 MPa.

[0031] The water sprinkler spray 24 can be attached to the support arm 46 in such a way that the distance from the water sprinkler spray 24 to the inner surface 56 of the inner cylinder 22 and the direction in which the water is sprayed from the water sprinkler spray 24 can be adjusted.

[0032] The blades 28 attached to the respective tip ends of the support arms 46 are made of rectangular metal plates having a length equal to the height direction length of the inner tube 22 of the fixed hollow cylinder 20, and as described above, are provided so as to form a predetermined inclination angle α with respect to the tangent direction of the rotation direction. A gap adjustment bolt 29 is attached to the end of the blades 28 on the support arm 46 side, for adjusting the gap between the tip ends 27 of the blades 28 and the inner circumferential surface 56 of the inner tube 22 of the fixed hollow cylinder 20. The gap between the tip ends of the blades 28 and the inner circumferential surface 56 of the inner tube 22 of the fixed hollow cylinder 20 is preferably about 0.1 to 0.2 mm. Due to manufacturing errors in the inner surface 56 of the inner tube 22 of the hollow cylinder 20, the minimum clearance between the inner surface 56 and the tip 27 of the blade 28 is approximately limited to 0.1 mm.However, this also depends on the thickness of the thin ice layer L formed on the inner surface 56, but if it exceeds 0.2 mm, it becomes difficult to obtain thin ice snowflakes with the desired snow quality, such as moisture content. Regarding the relationship between the spacing and the size of the detached snow flakes, we have confirmed that within this range, the impact on the size of the snow flakes, particularly their thickness, is small, and that the size and moisture content (water content) of the snow flakes are important parameters, along with the refrigerant temperature and / or water spray temperature, flow rate, and the number of rotations of the connecting rod 40.

[0033] A water temperature and flow rate regulator 61 is provided to adjust the temperature and flow rate of water supplied to the sprinkler nozzles 24. The water temperature and flow rate regulator 61 includes a water tank 62, a heater 64 for heating the water in the water tank 62, piping 66 connecting the water tank 62 to the sprinkler nozzles 24, and a liquid feed pump 68 installed along the piping 66. A control panel 70 controls the heater 64 and the liquid feed pump 68 via a control line 54 to adjust the water temperature and flow rate, and the water whose temperature and flow rate have been adjusted is supplied to the sprinkler nozzles 24 via the piping 66. The water supplied to the thin ice snowflake manufacturing device 18 may be tap water, with a temperature of 5 to 25°C. As described above, the liquid feed pump 68 supplies water from the water tank 62 via the piping 66 to the sprinkler nozzles 24, making it possible to adjust the amount of water sprayed per hour from the sprinkler nozzles 24 to the inner circumferential surface 56. A refrigerant temperature regulator 72 is provided to regulate the temperature of the refrigerant supplied into the hollow cylinder 20, and has a normal refrigerator section 74 including a condenser (not shown) and an inverter-controlled compressor (not shown), a return pipe 76 that returns the refrigerant from an evaporator (not shown) provided in the hollow cylinder 20 to the refrigerator section 74 via an evaporation pressure regulating valve 80, and a supply pipe 78 that supplies the refrigerant to the evaporator via an expansion valve 82. A control panel 70 controls the refrigerator section 74 and the evaporation pressure regulating valve 80 via a control line 54 to control the temperature and flow rate of the refrigerant supplied into the hollow cylinder 20, and the refrigerant whose temperature and flow rate have been adjusted is supplied to the evaporator in the hollow cylinder 20, where it cools the cooling surface to a predetermined temperature, and the heated refrigerant is returned to the refrigerator section 74.

[0034] The control panel 70 controls the drive motor 30 through the control line 54 to adjust the rotation speed of the connecting rod 40, thereby adjusting the amount of water received by the cooling surface per unit area per unit time on the inner surface 56 of the inner cylinder 22, which is the cooling surface, and the speed at which the thin ice layer L formed on the cooling surface is peeled off. With the above configuration, the water temperature and water volume are adjusted by the water temperature and water volume adjustment device 61 according to the desired size of the thin ice snowflakes, the moisture content (water content), and the desired amount of snow produced or snow made per hour, while the refrigerant temperature adjustment device 72 adjusts the refrigerant temperature, and the speed at which the thin ice layer L is peeled off is adjusted by controlling the drive motor 30. The desired size of the thin snowflakes varies depending on the content and conditions of the environmental test, but the thickness is 0.1 to 0.2 mm and the length is 1 to 20 mm, both of which are determined from the perspective of being able to fly the snow toward the test specimen using airflow from the upstream side of the test specimen.

[0035] Next, the airflow temperature and humidity control unit will be described with reference to FIG. The airflow temperature and humidity control unit 350 is generally composed of an airflow temperature sensor 352, an airflow humidity sensor 354, a specimen ambient temperature sensor 356, an airflow heating means 358, an airflow cooling means 360, an airflow humidifying means 362, an airflow temperature control means 364, and an airflow humidity control means 366, and the airflow heating means 358, the airflow cooling means 360, and the airflow humidifying means 362 are arranged in series in this order within the wind tunnel 16. The airflow temperature sensor 352 is provided downstream of the blower 25 that generates the airflow in the wind tunnel 16, and detects the temperature of the airflow generated by the blower 25 and transmits a detection signal to the airflow temperature control means 364. The airflow humidity sensor 354 is provided downstream of the blower 25 that generates the airflow in the wind tunnel 16, and detects the humidity of the airflow generated by the blower 25 and transmits a detection signal to the airflow humidity control means 366. Similarly, a test specimen ambient temperature sensor 356 is provided around the vehicle, and detects the temperature around the vehicle V when the airflow generated by the blower 25 passes around the vehicle V, and transmits a detection signal to the airflow temperature control means 364. Airflow cooling means 360 is provided downstream of blower 25 in the airflow direction, and is configured to cool the airflow generated by blower 25, thereby lowering the temperature of the airflow. Similarly, airflow heating means 358 is provided downstream of airflow cooling means 360 within air tunnel 16, and is configured to increase the temperature of the airflow by heating the airflow generated by blower 25. It is possible to determine whether airflow heating means 358 or airflow cooling means 360 is provided upstream, as appropriate, and when airflow heating means 358 or airflow cooling means 360 is on, it is also possible to turn off airflow cooling means 360 or airflow heating means 358, or to turn on both airflow cooling means 360 and airflow heating means 358 and use them together. An airflow humidifying means 362 is provided, which is disposed downstream of the airflow heating means 358 in the wind tunnel 16 and is configured to humidify the airflow generated by the blower 25, thereby increasing the humidity of the airflow.

[0036] An airflow temperature control means 364 is provided, for example, outside the wind tunnel 16, and receives detection signals from the airflow temperature sensor 352 and the specimen ambient temperature sensor 356, and accordingly transmits a control signal to the airflow heating means 358 and / or the airflow cooling means 360. More specifically, if the moisture content of the snowflakes is lower than the target value, the airflow cooling means 360 is not operated, and the snowflakes are heated by the airflow heating means 358 to melt them and increase their moisture content; if the moisture content of the snowflakes is higher than the target value, the airflow heating means 358 is not operated, and the snowflakes are cooled by the airflow cooling means 360 to cool them and decrease their moisture content. Similarly, airflow humidity control means 366 is provided, for example, outside the wind tunnel 16, and receives the detection signal of the airflow humidity sensor 354, thereby transmitting a control signal to the airflow humidifying means 362 and / or the airflow cooling means 360. More specifically, if the moisture content of the snowflakes is lower than the target value, the snowflakes are humidified by the airflow humidifying means 362 to increase the moisture content, and if the moisture content of the snowflakes is higher than the target value, the snowflakes are cooled by the airflow cooling means 360 to cool them and decrease the moisture content. In this case, the moisture content of the snowflakes can be measured in batches by conventionally known means, and based on the measurement results, the airflow temperature control means 364 can control the airflow heating means 358 and / or the airflow cooling means 360 and / or the airflow humidifying means 362. In addition, the blower 25 that generates the airflow performs the function of adjusting the airflow flow rate, and the airflow temperature control means 364 may control the airflow heating means 358 and / or the airflow cooling means 360 according to the set airflow rate. The airflow temperature may also be adjusted depending on the moisture content of the thin snow flakes produced by the thin snow flake manufacturing device 18. For example, if the moisture content of the thin snow flakes produced by the thin snow flake manufacturing device 18 is lower than the target moisture content used in the environmental test, the airflow cooling means 360 may not be operated, and the airflow heating means 358 may heat the airflow generated by the blower 25 to raise the temperature of the airflow and increase the moisture content of the thin snow flakes. On the other hand, if the moisture content of the thin snow flakes produced by the thin snow flake manufacturing device 18 is higher than the target moisture content used in the environmental test, the airflow heating means 358 may not be operated, and the airflow cooling means 360 may cool the airflow generated by the blower 25 to lower the temperature of the airflow and decrease the moisture content of the thin snow flakes. In particular, if the target moisture content of the artificial snow used in the test is high, the thin snow flakes may adhere to the inner surface of the thin snow flake manufacturing device 18, resulting in poor peeling and making it impossible to supply the required amount of artificial snow with the desired moisture content.However, it is best to limit the moisture content of the thin snow flakes in the thin snow flake manufacturing device 18 to a range that does not cause poor peeling, while raising the temperature of the airflow to melt the artificial snow and increase its moisture content as it is carried by the airflow and blown to the vehicle V. More specifically, when artificial snow is carried by parallel air currents generated in the wind tunnel 16 and blown toward the vehicle V downstream outside the wind tunnel, it is preferable to include a step of adjusting the temperature or humidity of the air current depending on the length of time the artificial snow is in contact with the air current before reaching the vehicle V, and carrying the artificial snow on the temperature- or humidity-adjusted air current; it is also possible to include a step of adjusting the temperature or humidity of the air current depending on the air current speed and / or the distance from the point where the artificial snow starts to come into contact with the air current in the wind tunnel 16 to the vehicle V, and carrying the artificial snow on the temperature- or humidity-adjusted air current. For example, if the set ambient temperature of vehicle V is low and the airflow velocity is high to simulate a snowstorm with a high moisture content, and the distance from the point where the artificial snow starts to come into contact with the airflow in wind tunnel 16 to test specimen V cannot be secured, the artificial snow will not be able to be in contact with the airflow for a sufficient length of time before reaching test specimen V, and there is a limit to the increase in the temperature of the airflow, so it is advisable to adjust the humidity of the airflow. In this case, if both the moisture content of the artificial snow and the required ambient temperature of the test specimen are set to specified values, and if the specified moisture content cannot be achieved within the contact time due to the temperature or humidity of the airflow alone, or if the specified moisture content cannot be achieved due to the distance to the test specimen, then both the temperature and humidity of the airflow must be adjusted.

[0037] The following describes how to operate the snow flying system 10 having the above configuration. The temperature inside the measurement room 300 in which the thin snowflake manufacturing device 18 is installed should be kept below 5°C, preferably below 3°C.

[0038] First, the desired size of the thin snowflakes and the desired production amount per hour (snowfall amount) are set according to the test objective of the snow environment test, and the airflow speed of the airflow MF in the wind tunnel 16 is set according to the traveling speed of the vehicle V to be simulated. In this case, it is preferable to adjust the temperature or humidity of the airflow in the wind tunnel 16 according to the moisture content of the artificial snow required for the environmental test using snow blown onto the vehicle V. More specifically, in the manufacturing stage of the thin snowflakes, the maximum moisture content is set according to the required size, the temperature of the airflow is adjusted according to the difference between the required moisture content of the thin snowflakes and the maximum moisture content, and the artificial snow is placed on the temperature-adjusted airflow. Alternatively, in the manufacturing stage of the thin snowflakes, a maximum moisture content may be set according to the required production volume, the temperature of the airflow may be adjusted according to the difference between the required moisture content of the thin snowflakes and the maximum moisture content, and the artificial snow may be placed on the temperature-adjusted airflow. Alternatively, the temperature of the airflow can be set according to the required ambient temperature of the test specimen, and the moisture content of the snowflakes can be adjusted during the manufacturing stage according to the difference between the required moisture content of the snowflakes and the moisture content of the snowflakes determined according to the set airflow temperature. When setting the temperature of the airflow according to the required ambient temperature of the test specimen, it is advisable to set the temperature of the airflow taking into account temperature fluctuations in the airflow caused by heat exchange between the airflow and the thin snowflakes supplied during the thin snowflake production stage. As an environmental test using snow blown onto vehicle V, depending on whether it is a snowstorm simulation test on a moving simulation vehicle V, a snowfall simulation test on a traffic jam simulation vehicle V, or a natural wind simulation test on a snow-covered vehicle V, the height at which the thin snow flakes start to fall naturally is positioned above tunnel 312 and stationary vehicle V, while the natural fall position is adjusted between tunnel 312 and stationary vehicle V, and the airflow speed within wind tunnel 16 is also adjusted. Figure 2 shows a case where thin snow flake manufacturing device 18 is installed between outlet 316 of wind tunnel 16 and stationary vehicle V for a snowstorm simulation test on a moving simulation vehicle V. The size and level of the outlet 316 of the contracted cavity 314 may be selected depending on the height of the vehicle V or the area of ​​the vehicle V where snow is desired to accumulate. In the case of a snowfall simulation test, the dampers installed at the upstream position of the flow straightening tunnel 312 and at the bypassed duct inlet are opened while the damper at the bypassed duct inlet side is closed upstream of the flow straightening tunnel 312, so that the airflow generated in the wind tunnel 16 is bypassed from the dedicated snowfall airflow outlet installed above the outlet 316 of the wind tunnel 16 and blown diagonally upward from a dedicated snowfall airflow outlet installed separately from the outlet 316.The thin snowflakes produced between the outlet 316 of the wind tunnel 16 and the vehicle V and allowed to fall naturally are carried on this airflow, causing snow to fall from above on the vehicle V.In the case of a snowstorm simulation test, the damper at the bypassed duct inlet side is closed while the damper at the upstream position of the flow straightening tunnel 312 is opened so that the airflow blows out only from the outlet 316 of the wind tunnel 16. Next, based on the desired size of the thin snowflakes and the desired production amount per hour (amount of snowfall) that have been set, the control panel 70 controls the water temperature and amount adjustment device 61, the refrigerant temperature adjustment device 72, and the drive motor 30 to adjust the temperature and flow rate of the water supplied to the sprinkler nozzle 24, the refrigerant temperature, and the rotation speed of the connecting rod 40. More specifically, by operating the refrigerator section 74, a refrigerant is supplied to the fixed hollow cylinder 20 via the pipes 76 and 78, and the temperature of the inner surface 56 of the inner tube 22 of the fixed hollow cylinder 20 is set to -10°C to -20°C, and the amount of water sprayed from the water spraying spray 24 and the rotation speed of the connecting rod 40 are set according to the size of the thin snowflakes and the production amount.

[0039] The mist-like water sprayed from the water spraying sprayer 24, which rotates counterclockwise together with the support arm 46, toward the inner circumferential surface 56 of the inner tube 22 of the fixed hollow cylinder 20 instantly freezes when it comes into contact with the inner circumferential surface 56 of the inner tube 22 of the fixed hollow cylinder 20, becoming a thin ice layer L. The thin ice layer L formed on the inner circumferential surface 56 of the inner tube 22 of the fixed hollow cylinder 20 is peeled off by the blade 28, which rotates counterclockwise together with the support arm 46, and becomes thin ice and snow flakes. The countless peeled thin ice and snow flakes fall from the discharge port 32.

[0040] According to the snow flying method configured as described above, when artificial snow is carried by an air current from behind and blown toward the test specimen, the temperature or humidity of the air current is adjusted according to the moisture content required for the artificial snow. By carrying the artificial snow toward the test specimen on an air current with adjusted temperature or humidity, artificial snow with the desired moisture content can be used. By using artificial snow with properties similar to those of natural snow and blowing it toward the test specimen, precise snow environment testing can be performed. In particular, according to the snow flying method using thin snow flakes S having the above-mentioned configuration, in an environmental test in which artificial snow is carried by the air current MF in the wind tunnel 16 toward a test specimen, the hourly production amount and snow quality of artificial snow made of thin snow flakes S are set according to the environmental test using snow flying toward the test specimen, and thin snow flakes S of a predetermined production amount per hour and predetermined snow quality are produced at a level above the outlet 316 of the wind tunnel 16, and the produced thin snow flakes S are allowed to fall naturally into the wind tunnel 16 or between the outlet 316 of the wind tunnel 16 and the test specimen.As a result of the thin snow flakes S, there is no need to transport flake-shaped ice pieces by the transport air flowing in the transport pipe after they have been crushed by an ice crusher, as in the conventional method, and there is no need to install multiple nozzles for the transport pipe at each level in the wind tunnel 16 and route them into the wind tunnel 16, and there is no need to install multiple nozzles for the transport pipe at each level in the wind tunnel 16 and route them along the transport pipe. This eliminates the need to crush ice into ice pellets of a specified size using an ice crusher and then melt the crushed ice to turn it into wet snow, allowing the amount of artificial snow produced and the quality of the snow to be adjusted all at once during the production stage. Meanwhile, with conventional crystalline snow, it was technically difficult to continuously supply the amount of snow needed for environmental testing, such as testing in which snow is blown toward a stationary vehicle V on the air currents generated in the wind tunnel 16. However, with this system, naturally falling thin snowflakes S are blown toward the test specimen on the air currents flowing from upstream of the test specimen, allowing the required amount to be continuously supplied on the spot. Overall, the quality of this artificial snow is closer to natural snow than that of artificial snow made from ice pellets, and it avoids the air current disturbances that occur when a transport pipe is placed inside the wind tunnel 16. Furthermore, it makes it possible to conduct sophisticated tests, whereas with crystalline snow, it is limited to snowfall tests.

[0041] In particular, in the case of a test to evaluate the actual snowfall intensity on a vehicle V, the airflow speed of the airflow MF generated in the wind tunnel 16 is set according to the running speed simulated by the stationary vehicle V, and the amount of thin snowflakes produced per hour by the thin snowflake manufacturing device 18 is set according to the set airflow speed and the actual snowfall intensity to be reproduced. Here, snowfall intensity is the water depth (mm / h) equal to the weight of snow accumulated per unit area on the ground surface per unit time, and actual snowfall intensity is the snowfall intensity when it falls to the ground, for example, when snow is blown by the wind onto power lines, taking into account the wind speed, which can in some cases be several tens of times greater than the snowfall intensity.In order to evaluate actual snowfall intensity, it is necessary to set the desired amount of snow production or desired amount of snow made, while simulating the wind speed using the airflow MF from the wind tunnel 16. As described above, using the wind tunnel 16 equipment, it is possible to produce thin snowflakes on the spot, let them fall naturally, and have them carried by the air current behind them and fly towards the test specimen. Therefore, by adjusting the falling position of the thin snowflakes and combining it with the air current, it is possible to use a single wind tunnel 16 equipment to perform various snow environment tests such as simulating snowfall and blizzards.

[0042] Although the embodiments of the present invention have been described in detail above, those skilled in the art can make various modifications and changes without departing from the scope of the present invention. For example, in this embodiment, when snow falls on a stationary vehicle V, the airflow MF generated in the wind tunnel 16 is bypassed diagonally upward from the outlet 316. However, instead of bypassing the airflow MF generated in the wind tunnel 16 diagonally upward from the outlet, an airflow generating device can be installed above the outlet 316, generating an airflow diagonally upward, and creating an airflow between the outlet 316 and the stationary vehicle V, and the naturally falling thin snowflakes can be carried on this airflow, causing snow to fall on the stationary vehicle V. In addition to bypassing the airflow MF generated in the wind tunnel 16, an airflow generating device can also be used in parallel. For example, in this embodiment, as shown in Figure 2, the thin snow flake manufacturing device 18 has been described as being installed between the outlet 316 of the contraction cavity 314 and the stationary vehicle V, but it is not limited to this, and it may be installed above the contraction cavity 314 as long as the countless thin snow flakes S manufactured by the thin snow flake manufacturing device 18 can be reliably blown away by the airflow MF generated in the wind tunnel 16 without accumulating in the wind tunnel 16 when they naturally fall. In this case, it is advisable to set the speed of the airflow MF in the wind tunnel 16 according to the flow rate of the thin snow flakes naturally falling in the wind tunnel 16 so that they do not accumulate. [Brief explanation of the drawings]

[0043] [Figure 1] 1 is an overall configuration diagram of a snow flying system according to an embodiment of the present invention. [Figure 2] 1 is a partial view showing snow falling on a stationary vehicle V of a snow-flying system according to an embodiment of the present invention. [Figure 3] FIG. 1 is a schematic side view showing a thin ice snowflake manufacturing device 18 of a snow flying system according to an embodiment of the present invention. [Figure 4] FIG. 1 is a schematic plan view showing a thin ice snowflake manufacturing device 18 of a flying snow system according to an embodiment of the present invention. [Explanation of symbols]

[0044] S Thin ice snowflake MF Airflow J Airflow V Stationary vehicle θ predetermined angle interval α Blade inclination angle w Width of circumferential groove 60 d Depth of circumferential groove 60 L thin ice layer 10 Snow Flying System 11 Wind tunnel equipment 16 Wind tunnel 18 Thin ice snowflake manufacturing device 20 Fixed hollow cylinder 21 Hollow part 24 Watering Spray 27 Tip 28 blades 30 Drive motor 32 Outlet 40 Connecting rod 42 End 44 Connecting rod rotation mechanism 46 Support arm 48 Tires 50 Vertical rotating shaft 52 Rotating shaft support 54 Control Line 56 Inner surface 58 Outer surface 60 Circumferential groove 61 Water temperature water adjustment device 62 Water Tank 64 Heater 66 Piping 68 Liquid transfer pump 70 Control Panel 72 Refrigerant temperature adjustment device 74 Refrigerator part 76 Return pipe 78 Supply pipe 80 Flow control valve 300 Measurement room 302, 304, 306, 308 Bent Torso 310 Second diffuser 306 Third Bent Torso 308 4th bent trunk 312 Straightening body 314 Contraction Body 316 Air Outlet 317 Receiving Port 350 Airflow, Temperature, and Humidity Control Unit 352 Airflow Temperature Sensor 354 Airflow Humidity Sensor 356 Test specimen ambient temperature sensor 358 Airflow heating means 360° airflow cooling means 362 Airflow humidification means 364 Airflow temperature control means 366 Airflow and Humidity Control Means

Claims

1. This method involves placing artificial snow on an air current from behind and blowing it towards a test piece, and is characterized by comprising a step of adjusting the temperature or humidity of the air current according to the moisture content required for the artificial snow, and placing the artificial snow on the temperature- or humidity-adjusted air current.

2. 2. The snow blowing method according to claim 1, wherein the method comprises the steps of adjusting the temperature and / or humidity of the airflow in accordance with the required ambient temperature of the test specimen, and causing the artificial snow to be blown on the temperature- and / or humidity-adjusted airflow, when the artificial snow is blown on parallel airflows generated in a wind tunnel toward the test specimen downstream outside the wind tunnel.

3. A step of setting the amount of artificial snow produced per hour and the quality of snow made of thin snow flakes according to an environmental test using snow blown onto a test specimen; producing thin snow flakes of a predetermined production amount and a predetermined snow quality per hour at a level above the outlet of the wind tunnel; A step of allowing the produced thin snowflakes to fall naturally into a wind tunnel or between the outlet of the wind tunnel and the test piece; A step of making naturally falling thin snowflakes fly toward the test specimen on an air current from the upstream side of the test specimen toward the test specimen; and 3. The snow flying method according to claim 1, further comprising a step of determining a set temperature or humidity of the airflow depending on the distance between the falling position of the thin snowflakes and the test piece.

4. A step of allowing the produced thin snowflakes to fall naturally between the outlet of the wind tunnel and the test piece; 4. The snow flying method according to claim 3, further comprising a step of causing naturally falling thin snow flakes to fall from above the test piece on the air current flowing from the upstream side of the test piece toward the test piece.

5. 4. The snow flying method according to claim 3, wherein the snowfall stage involves directing the airflow from the upstream side of the test piece toward the test piece obliquely upward from a dedicated airflow outlet for snowfall that is provided separately from the outlet, and causing naturally falling thin snow flakes to fall from above the test piece on the obliquely upward airflow.

6. The step of letting the thin ice snowflakes fall naturally into the wind tunnel.

4. The snow blowing method according to claim 3, further comprising a step of blowing naturally falling flakes of snow toward the test piece as a snowstorm by carrying them on an air current flowing toward the outlet in the wind tunnel.

7. 4. The snow blowing method according to claim 3, further comprising the step of: after the snow has accumulated on the test piece, simulating natural wind acting on the test piece by the air current flowing from the upstream side of the test piece toward the test piece.

8. 3. The method for flying snow according to claim 1, wherein the step of producing the thin ice flakes comprises spraying water on the cooling surface to form a thin ice layer, peeling off the formed thin ice layer, and allowing it to fall naturally.

9. 9. The snow flying method according to claim 8, further comprising the steps of: in the step of producing the thin snow flakes, setting a maximum moisture content according to the required size; adjusting the temperature of the airflow according to the difference between the required moisture content of the thin snow flakes and the maximum moisture content; and placing the artificial snow on the temperature-adjusted airflow.

10. 9. The snow flying method according to claim 8, further comprising the steps of: in the step of producing the thin snow flakes, setting a maximum moisture content according to the required production amount; adjusting the temperature of the airflow according to the difference between the required moisture content of the thin snow flakes and the maximum moisture content; and causing the artificial snow to float on the temperature-adjusted airflow.

11. 9. The snow flying method according to claim 8, wherein the temperature of the airflow is set according to the required ambient temperature of the test specimen, and the moisture content of the snowflakes is adjusted during the snowflake production stage according to the difference between the required moisture content of the snowflakes and the moisture content of the snowflakes determined according to the set airflow temperature.

12. A snow flying method as described in claim 11, wherein when the temperature of the airflow is set according to the required ambient temperature of the test specimen, the temperature of the airflow is set taking into account temperature fluctuations of the airflow caused by heat exchange between the airflow and the thin snowflakes supplied during the thin snowflake production stage.

13. 4. The snow flying method according to claim 3, wherein the thickness of the thin snow flakes is 0.1 to 0.2 mm, and the length is 1 to 20 mm.

14. 4. The snow blowing method according to claim 3, wherein the environmental test for blowing snow onto a test specimen is carried out using a wind tunnel having, in that order, a flow straightening tunnel that directs airflow generated upstream from an outlet toward the test specimen and a flow contraction tunnel also having an outlet, and the method includes the steps of positioning the height at which the thin snow flakes start to fall naturally above the vehicle, adjusting the position of the free fall between the flow straightening tunnel and the vehicle, and adjusting the airflow speed in the wind tunnel and the airflow temperature or airflow humidity, depending on whether the test is a snowstorm simulation test for a moving simulation vehicle, a snowfall simulation test for a traffic jam simulation vehicle, or a natural wind simulation test for a snow-covered vehicle.

15. 15. The snow blowing method according to claim 14, wherein the free-falling of the thin snow flakes is performed in a rectification cavern, and the free-falling start height of the thin snow flakes is positioned above the rectification cavern and the vehicle.

16. 2. The method for blowing snow according to claim 1, wherein the method comprises adjusting the temperature and / or humidity of the airflow depending on the length of contact time of the artificial snow with the airflow before reaching the test piece, in the case where the artificial snow is blown on parallel airflows generated in a wind tunnel and blown towards the test piece downstream outside the wind tunnel, and causing the artificial snow to be blown on the temperature- and / or humidity-adjusted airflow.

17. When artificial snow is carried by parallel air currents generated in a wind tunnel and blown towards a test piece downstream outside the wind tunnel, the air current speed and / or the speed in the wind tunnel 17. The snow flying method according to claim 16, further comprising a step of adjusting the temperature and / or humidity of the airflow depending on the distance from the contact start point between the artificial snow and the airflow to the test piece, and causing the artificial snow to be carried by the temperature- and / or humidity-adjusted airflow.

Images