JP7175232B2 - Snow accretion shape prediction method and snow accretion suppression shape of snow accreted body - Google Patents

Description

The present invention relates to a snow accretion shape prediction method and a snow accretion object shape for suppressing snow accretion.

When snow adheres to snow-covered objects such as power lines and traffic lights in snowfall areas, snow clumps form on the snow-covered surfaces. or collapse. In addition, power outages may occur when electric wires come into contact with each other and short-circuit due to the rebound of snow that has fallen.

In order to suppress the occurrence of such damage due to snow accretion, it is necessary to reduce the amount of snow accretion on the object to which snow is accreted. The reduction of the amount of snow accretion on a snow-covered object is achieved, for example, by developing a snow-covered object having a shape of a snow-covered surface on which snow accretion is less likely to occur. In order to appropriately develop such a shape, it is important to accurately grasp the amount of snow accretion on the snow-adhering body and the final shape of the snow accretion.

Japanese Patent Laid-Open No. 2002-100001 discloses a wire snow shape detection device. According to the snow accretion shape detection device described in Patent Document 1, reflective red sensors radially arranged along the radial direction inside the electric wire are installed at a plurality of positions in the longitudinal direction of the electric wire, thereby three-dimensionally Snow accretion shape can be detected in real time.

JP-A-10-267632

As shown in Japanese Unexamined Patent Application Publication No. 2002-100000, it has been proposed to detect the shape of snow accretion on a snow accreted body in real time. On the other hand, however, the mechanism of snow accretion on the snow-covered body has not yet been elucidated, and great effort is required to develop the shape of the snow-clad body. In other words, it is difficult to know in advance the snow accretion shape and the amount of snow accretion on the object to be covered with snow.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a snow-covering object capable of appropriately predicting the shape of snow accretion on the snow-covering object and appropriately suppressing snow accretion based on the predicted snow accretion shape. do.

In order to achieve the above object, the present invention provides a snow accretion shape prediction method for a snow accretion object, comprising: Based on the reference velocity of the airflow in the direction tangential to the snow , a reference angle corresponding to the velocity of the airflow, which is the angle between the tangential direction of snow accretion at the edge and the direction perpendicular to the airflow, is calculated. and predicting the cross -sectional shape of the snow accretion as an angle formed by the tangential direction of the accretion of snow at the end portion and the orthogonal direction of the airflow in the steady state of the accretion of snow.

According to the present invention, only by setting the reference speed in the tangential direction of the snow-covered surface, which is uniquely determined by the snow quality of the floating snow particles, snow accretion at the end of the snow-covered surface according to the airflow velocity can be achieved. By calculating the reference angle of , it is possible to easily predict the snow accretion shape with respect to the snow accreted body.

The snow-covered surface may be a surface of the snow-covered body that is included in a projection range of the airflow.

Before predicting the cross-sectional shape of the accreted snow, the relationship between the snow quality, the airflow velocity, and the reference angle may be derived in advance.

The snow quality may be determined by the water content and particle shape of the snow.

According to another aspect of the present invention, there is provided a snow accretion suppressing shape of a snow accretion object, wherein the snow accretion tangential direction at the edge of the snow accretion surface of the snow accretion object is predetermined according to the snow quality. calculating the reference angle at the end according to the speed of the airflow based on the reference speed of the airflow in the tangential direction of the snow-covering surface of the snow-covering body and the orthogonal direction of the airflow to the snow-covering body The snow-covered surface is determined so that the angle between and is greater than or equal to the reference angle.

The snow-covering object may be a bogie cover of a train.

According to the present invention, it is possible to appropriately predict the shape of snow accretion on a snow-covered body, and to provide a snow-clad body capable of appropriately suppressing snow accretion based on the predicted snow accretion shape. .

It is (a) side view (b) top view which shows the outline of a structure of a snow-arrangement apparatus typically. FIG. 4 is a plan view schematically showing a snow-covered body held by a holding portion; 4 is a flow chart showing main steps of a snow accretion test. It is a graph which shows typically the relationship between test time and the amount of snow accretion. FIG. 4 is an explanatory diagram schematically showing the shape of snow accretion on a specimen; FIG. 4 is an explanatory diagram schematically showing the shape of snow accretion on a specimen; FIG. 5 is a plot diagram showing an example of snow accretion test results; FIG. 5 is a plot diagram showing an example of snow accretion test results; FIG. 5 is a cross-sectional view showing an example of snow accretion test results; FIG. 5 is a cross-sectional view showing an example of snow accretion test results; 4 is a flow chart showing main steps of a snow accretion shape prediction method; FIG. 5 is an explanatory diagram showing main steps of a snow accretion shape prediction method; FIG. 10 is an explanatory diagram showing another step of the snow accretion shape prediction method;

Hereinafter, a snow accretion device for performing a snow accretion test for predicting the shape of snow accretion according to the present invention will be described with reference to the drawings. In this specification, elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description.

<Structure of Snow Arresting Device>
FIG. 1 is (a) a side view and (b) a plan view schematically showing the outline of the configuration of the snow-applying device 1. FIG. In the snow accretion apparatus 1, the snow sample S' is sprayed onto the test object 10 to make it snow, and the shape of the snow sample S' accreted onto the test object 10 is imaged.

As the specimen 10 in this snow accretion test, a square prism (152 mm×152 mm×152 mm) was used as a simple shape model. In addition, on the surface of the specimen 10, a felt (felt ( not shown) was attached.

As shown in FIG. 1, the snow-applying device 1 includes an air blower 11 for forming a test airflow F' inside the snow-applying device 10, and a snow supply device for supplying a snow sample S' inside the snow-applying device 1. It has a portion 12 , a holding portion 13 that holds the test piece 10 , and a camera 14 for taking an image of the shape of the snow sample S′ accreting onto the test piece 10 .

The blower 11 forms a test airflow F′ in the horizontal direction (the X-axis direction in FIG. 1) inside the snow-applying device 1 . In the following description, a test airflow F' is formed inside the snow attachment device 1 from the X-axis direction negative direction side toward the positive direction side, and the upstream side (X-axis direction negative direction) of the test airflow F' is formed. direction) may be simply referred to as the "upstream side", and the downstream side of the test airflow F' (positive direction in the X-axis direction) may simply be referred to as the "downstream side".

The snow supply unit 12 is provided, for example, above the ceiling surface of the snow collecting device 1 and downstream of the blower 11, and is capable of supplying the snow sample S' from the ceiling surface of the snow collecting device 1 to the interior of the snow collecting device 1. It is configured. That is, the snow sample S' is configured to be supplied to the test airflow F' formed inside the snow-applying device 1 . Also, the amount of the snow sample S' supplied to the snow-applying device 1 is adjustable.

The holding unit 13 is provided downstream of the snow supplying unit 12 inside the snow-applying device 1, whereby the snow sample S' supplied from the snow supplying unit 12 rides on the test airflow F', snow lands on the covered snow surface 10a, which is the projection range of the test airflow F'. The holding part 13 is configured so that the held specimen 10 can be moved in the X-axis direction and the Z-axis direction. That is, the height H of the specimen 10 from the floor surface and the distance L between the snow supply section 12 are adjustable.

Further, as shown in FIG. 2, the holding portion 13 is configured to be able to rotate the specimen 10 around the vertical axis. In the following description, the angle formed by the traveling direction of the test airflow F' (X-axis direction in the drawing) and the snow-covered surface 10a in a cross-sectional view with respect to the test airflow F' is referred to as the "wind direction angle θ (45° ≤ θ ≤ 90°)”.

When the test body 10 is rotated as shown in FIG. 2, two surfaces, which are the projection range of the test airflow F', are set as the snow-covering surfaces 10a on which the snow sample S' adheres. In this case, the wind direction angle θ on one surface (the surface on the positive Y-axis direction side) of the snow-attached surface 10a is set to the wind direction angle θ1, and the other surface (the surface on the negative Y-axis direction side) of the snow-attached surface 10a is The wind direction angle θ at is set to the wind direction angle θ2.

The camera 14 is provided above the specimen 10 held by the holding portion 13 and picks up an image of the snow accretion shape of the snow sample S' on the specimen 10 . In addition, the camera 14 is capable of capturing an image of the snow accretion shape of the specimen 10 at predetermined time intervals, and by comparing the snow accretion shapes captured in this manner for each time, the growth rate of snow accretion can be measured. can be done.

Although the snow accretion device 1 for conducting the snow accretion test has the configuration as described above, the configuration of the snow accretion device 1 is not limited to this, and may take any configuration.

<Snow accretion test method>
Next, a snow accretion test method using the snow accretion device 1 configured as described above will be described. FIG. 3 is a flow chart showing the main steps of the snow accretion test according to this embodiment.

In the snow accretion test, first, the specimen 10 is placed on the holder 13 as a preliminary preparation, and the wind direction angle θ is determined. Also, a snow sample S' is put into the snow supply unit 12 (step P1 in FIG. 3).

Moreover, the density distribution of the snow sample S' inside the snow-applying device 1 does not become uniform depending on the wind speed of the test airflow F'. Therefore, as a preliminary preparation, the position of the specimen 10, that is, the height H and the distance L are adjusted according to the density distribution (step P2 in FIG. 3).

When the preparation for the snow accretion test is completed, the supply of the snow sample S' from the snow supply unit 12 is started, and the test airflow F' is formed by the blower 11 at a predetermined wind speed, and the snow sample S is applied to the test body 10. ' is started (step P3 in FIG. 3).

When the snow sample S' starts to adhere to the specimen 10, the camera 14 takes an image of the shape of the snow accretion at predetermined time intervals (step P4 in FIG. 3).

As shown in FIG. 4, the amount of snow accretion of the snow sample S' on the specimen 10 increases with time, and reaches a steady state under restrictions such as the size of the specimen 10 and the size of the test space. Specifically, first, the snow sample S' is sprayed and attached to the snow-covered surface 10a of the specimen 10 (process A in FIG. 4). After the snow accretion surface 10a is covered with the snow sample S' to form the snow accretion surface Sa, the snow sample S' is subsequently sprayed onto the snow accretion surface Sa, and the snow grows (see FIG. 4). process B). When the snow sample S' is sprayed onto the snow accreted surface Sa and the accreted snow grows sufficiently, the accreted snow shape does not change any more, ie, reaches a steady state (process C in FIG. 4).

The "snow-covered surface Sa" is the surface formed by the attached snow sample S'. That is, as shown in FIG. 5, it is a surface formed in process A by adhering a snow sample S' to the snow-covered surface 10a and grown in process B by adhering the snow sample S'.

The imaging in step P4 is performed at predetermined time intervals until the amount of accreted snow reaches a steady state.

When the amount of accreted snow on the test object 10 reaches a steady state, the supply of the snow sample S' from the snow supply unit 12 and the formation of the test airflow F' by the blower 11 are stopped (step P5 in FIG. 3). Then, the thickness, mass, density, and growth rate of the snow deposited on the specimen 10 are measured and calculated (step P6 in FIG. 3), and a series of snow deposition tests is completed.

In this embodiment, the test was conducted by changing the wind speed of the test airflow F', the wind direction angle θ1, and the installation position of the test body 10 under the conditions shown in Table 1 below. Specifically, as shown in Table 1, under the conditions that the test airflow F′ has a wind speed of 2.5 m/s, a distance L of 1328 mm, and a height H of 355 mm, the wind direction angles θ1 are set to 45°, 60°, and 75°. ° and 90°. The wind direction angle θ1 was changed to 60°, 75°, and 90° under the conditions that the test airflow F′ had a wind velocity of 5.0 m/s, a distance L of 3014 mm, and a height H of 330 mm. The wind direction angle θ1 was set to 90° under the conditions that the test airflow F′ had a wind speed of 10.0 m/s, a distance L of 3014 mm, and a height H of 330 mm.

<Snow accretion test results>
Next, based on the snow accretion test results obtained from the above snow accretion test, the snow accretion of the snow sample S' on the snow-covered surface 10a will be considered. Tables 2 and 3 show an example of snow accretion test results.

The snow accretion angle φ shown in Table 2 is the angle formed by the snow accretion surface 10a and the accretion snow. That is, as shown in FIG. 5(a), it is an angle formed by the formation direction of the snow-attached surface 10a and the tangential direction of the snow-attached edge of the snow-attached surface 10a. The snow accretion angle at one end of the snow-covered surface 10a (the end of the snow-covered surface 10a in the positive Y-axis direction) is the snow accretion angle φ1, and the other end (the negative Y-axis direction of the snow-covered surface 10a) is The snow accretion angle at the edge) is defined as a snow accretion angle φ2. Note that Table 2 describes the results for the snow accretion angle φ1.

Further, the reference angle ψ shown in Table 2 is defined as a reference plane extending in a direction perpendicular to the traveling direction of the test airflow F' as shown in FIG. , and is an angle formed by the reference surface 10s and the accreted snow. That is, as shown in FIG. 5(b), it is an angle formed by the orthogonal direction of the test airflow F' and the tangential direction of snow accretion at the edge of the snow-accreted surface 10a. The reference angle at one end of the snow-covered surface 10a is the reference angle ψ1, and the reference angle at the other end is the reference angle ψ2. Note that Table 2 describes the results of the reference angle ψ1. Also, the reference angle ψ can be expressed by the following equation (1).
Reference angle ψ = snow accretion angle φ + (90° - wind direction angle θ) (1)

The "maximum thickness T" in Table 2 indicates the maximum snow thickness of the snow sample S' in the vertical direction from the snow-covered surface 10a as shown in FIG.

The terms "tangential velocity" and "normal velocity" in Table 3 respectively refer to the tangential component (Usinφ) and modulus The linear direction component (U cos φ) is shown respectively.

As shown in Table 2 and FIG. 7, even if the wind velocity of the test airflow F' was the same, the snow accretion angle φ varied depending on the wind direction angle θ. Specifically, as the wind direction angle θ increased, the snow accretion angle φ1 increased. Also, under the test conditions of this time, snow accretion occurred up to the wind direction angle θ = 45° at a wind speed of 2.5 m/s, but no snow accretion occurred at a wind speed of 5.0 m/s at a wind direction angle θ = 60°. . Also, at a wind speed of 10 m/s, no snow accretion occurred even when the wind direction angle θ was 90°.

On the other hand, as shown in Table 2 and FIG. 8, the reference angle ψ1 showed a substantially constant value regardless of the wind direction angle θ.

Figures 9(a) to (d) schematically show snow accretion shapes in a steady state when the wind direction angle θ is changed to 90°, 75°, 60°, and 45° at a wind speed of 2.5 m/s. FIG. 3 is a schematic cross-sectional view; As shown in Table 2 and FIG. 9, at a wind speed of 2.5 m/s, the reference angle ψ1 was about 60° regardless of the wind direction angle θ. At a wind speed of 5 m/s, the reference angle ψ1 was about 30° regardless of the wind direction angle θ.

Although not shown, the snow accretion angle φ2 decreased as the wind direction angle θ increased. On the other hand, the reference angle ψ2 shows a constant value regardless of the wind direction angle θ, and the reference angle ψ2 is about 60° at a wind speed of 2.5 m/s, and about 30° at a wind speed of 5 m/s. became.

In other words, the reference angles .psi.1 and .psi.2 show approximately constant values regardless of the wind direction angle .theta., and the reference angles .psi.1 and .psi.2 have approximately the same values.

Further, as shown in Table 3, the tangential velocity (Usin ψ) of the test airflow F′ at both ends of the snow-covered surface 10a varies in the range of 2.5 m/s to 10 m/s. 2.3 m/s to 2.5 m/s even when the velocity was reduced, showing an approximately constant value. This is considered to be due to the fact that, in the steady state, the snow sample S' that has collided with the snow-covered surface Sa does not adhere to the snow and is reflected in the tangential direction.

The inventors also found that the tangential velocity (Usin ψ) of the test airflow F' varies depending on the snow quality of the snow sample S'. Specifically, it was found that, for example, the tangential velocity (U sin ψ) of the test airflow F′ increases when the amount of moisture contained in the snow sample S′ increases. As described above, if the snow quality of the snow sample S', specifically, the amount of water contained in the snow sample S', the shape of the snow sample S', etc., are constant, the tangential velocity (U sin ψ) in the steady state is It was found that it is uniquely defined.

That is, since the tangential velocity (U sin ψ) is uniquely determined according to the snow quality of the snow sample S′, the determination of the wind velocity (U) of the test airflow F′ provides the snow accretion standard for the snow-covering surface 10a. The angle ψ can be uniquely derived. In other words, the relationship between the wind speed (U) of the test airflow F' and the reference angle ψ can be uniquely derived according to the snow quality of the snow sample S'. Note that the tangential speed (Usin ψ) that is uniquely determined according to the snow quality may be hereinafter referred to as the “reference speed”.

In view of these, whether or not the snow sample S' lands on the snow accretion surface Sa depends on whether or not the snow accretion angle φ with respect to the snow accretion surface 10a reaches the reference angle ψ derived from the above relationship. It is thought that it is determined by This can be rephrased as that the snow accretion angle θ has a critical angle depending on the wind speed of the test airflow F′. Then, when the snow accretion angle φ reaches such a critical angle, the reference speed of the test airflow F′ on the snow accretion surface Sa becomes a constant value corresponding to the snow quality. is considered to reach a steady state.

Further, as shown in Table 2, when the wind speed of the test airflow F' increased, the normal direction velocity (U cos ψ) of the test airflow F' at both ends of the snow-covered surface 10a increased.

Also, as shown in Table 2, there was no significant correlation between the wind direction angle θ and the snow accretion density. On the other hand, as the wind speed of the test airflow F' increased, the snow density increased.

The snow accretion density is considered to be affected by the normal direction velocity of the test airflow F' on the snow accretion surface Sa, that is, the impact in the vertical direction when the snow sample S' is incident on the snow accretion surface Sa. Then, it is conceivable that the wind velocity of the test airflow F' has a large effect on the normal velocity, while the effect of the wind direction angle θ is sufficiently small.

Next, the measurement results of the growth rate of snow accretion on the snow-covered surface 10a will be discussed with reference to Table 4 and FIG. Table 4 shows an example of the measurement results of the thickness of snow accreted on the snow-covered surface 10a for each predetermined time. In the snow accretion test according to the present embodiment, as described above, the camera 14 was used to image the snow accretion shape every five minutes. The "thickness of accreted snow" indicates the maximum thickness of accreted snow of the snow sample S' in the vertical direction from the snow-accreted surface 10a at each time. 10(a) to (d) show the snow-covered surface 10a when the wind direction angle θ is changed between 90° and 75° under the condition that the wind speed is 2.5 m/s or 5.0 m/s. FIG. 10 is a plan view schematically showing an example of the growth process of the snow accretion shape for each. The snow accretion shape indicated by the solid line in the figure indicates the snow accretion shape in the steady state, and the snow accretion shape indicated by the broken line indicates the snow accretion shape in the process of reaching the steady state.

As shown in Table 4 and FIG. 10, the difference value of the accreted snow thickness over time, that is, the growth rate of the accreted snow on the snow-covered surface 10a is constant with respect to the vertical direction of the snow-covered surface 10a. all right. More specifically, it was found that the snow accretion of the snow sample S' onto the snow-accreted surface 10a proceeds at a constant speed until the snow accretion angle φ reaches the critical speed. Moreover, it was found that the growth of such accreted snow progresses at a constant speed with respect to the normal direction of the snow-covered surface 10a regardless of the wind direction angle θ and the wind speed.

The present inventors also found that the growth rate of snow on the snow-covered surface 10a changes according to the amount of supplied snow sample S'. Specifically, it was found that the growth rate of snow accretion increases, for example, in proportion to the supply amount of the snow sample S'.

<Snow accretion shape prediction method>
Next, a method for predicting the snow accretion shape for the snow-accreted body 20 based on the above snow accretion test results will be described. FIG. 11 is a flowchart showing main steps of the snow accretion shape estimation method. FIG. 12 is an explanatory diagram of main steps of the snow accretion shape estimation method. In addition, in the snow accretion shape prediction according to the present embodiment, in a cross-sectional view (a plan view of the snow accretion device 1 shown in FIG. 1(b)) in the traveling direction of the airflow F, the Estimate the snow accretion shape.

In order to execute the snow accretion shape prediction according to the present embodiment, the reference speed at the edge of the snow-covering surface 20a of the snow-covering body 20, which is uniquely determined based on the snow quality, is obtained in advance. Also, from the obtained reference speed, the relationship between the wind speed of the airflow F and the reference angle at both ends of the snow-covered surface 20a is calculated (step Q0 in FIG. 11). That is, the relationship between the wind speed of the airflow F and the reference angle, which is uniquely determined according to the snow quality, is calculated. Note that the relationship between the wind speed and the reference angle ψ is at least the relationship under the wind speed condition of the airflow F for which the snow accretion shape is to be predicted.

In predicting the shape of snow accretion, first, as shown in FIG. 12(a), the snow accretion surface 20a and the reference surface 20s of the snow accretion object 20 are set (step Q1 in FIG. 11). Here, the snow-covered surface 20 a is the entire surface on which the snow S rides on the airflow F and directly collides with it, and is the projection range of the airflow F with respect to the snow-covered object 20 . The reference plane 20s is set in a direction perpendicular to the traveling direction of the airflow F at both ends of the snow-covered surface 20a in a cross-sectional view, that is, at both ends of the projection range.

After setting the snow-covered surface 20a and the reference surface 20s, the reference angle ψ as the critical angle for the wind speed of the airflow F is derived from the relationship obtained in advance in step Q0 (step Q2 in FIG. 11). At this time, since the reference angle ψ is uniquely determined by the wind speed regardless of the wind direction angle θ, it has the same value at both ends of the snow-covered surface 20a. As described above, the reference angle ψ is the angle formed by the reference surface 20s and the tangential direction of snow on the edge of the snow-covered surface 20a in the steady state.

Then, when the reference angle ψ is derived, as shown in FIG. 12B, at both ends of the snow-covered surface 20a set in step Q1, from the reference surface 20s at the reference angle ψ set in step Q2, steady Draw a tangent to the snow accretion shape in the state (step Q3 in FIG. 11).

Subsequently, as shown in FIG. 12(c), the tangent line drawn in step Q3 is extended upstream of the airflow F (step Q4 in FIG. 11). Then, the region surrounded by the tangent line drawn in step Q4 and the snow-covered surface 20a is estimated to be the maximum snow-covered region R1 in a cross-sectional view in the traveling direction of the airflow F, as shown in FIG. 12(d). can do.

Note that arcs may be drawn from both ends of the snow-covered surface 20a as shown in FIG. 13(a) according to the tangent lines drawn in step Q3 (step Q5 in FIG. 11).

Then, the area surrounded by the arc drawn in step Q3 and the snow-covered surface 20a is estimated to be the snow-covered area R2 in a cross-sectional view in the traveling direction of the airflow F as shown in FIG. 13(b). may

As described above, according to the present invention, it is possible to predict the snow accretion shape for the snow-attached body 20 . Specifically, the snow accretion angle ψ as the critical angle of the airflow F with respect to the wind velocity U is uniquely determined according to the snow quality. In this manner, the critical angle of snow accretion with respect to the snow-accreted surface 20a is uniquely determined by the wind speed of the airflow F, so the shape of snow accretion can be appropriately predicted according to the wind speed.

According to this embodiment, only by setting the tangential velocity of the snow-covered surface that is uniquely determined by the snow quality of the floating snow particles, the reference angle of snow accretion at both ends of the snow-covered surface according to the wind speed can be calculated to easily predict the snow accretion shape for the snow-covered object.

For example, when the wind direction angle θ or the wind speed of the airflow F with respect to the snow-attached body 20 changes, the shape of the snow-attached body 20 also changes accordingly. In such a case, it is possible to appropriately predict a change in snow accretion shape by newly performing the snow accretion shape prediction described above based on the changed wind direction angle θ and wind speed.

<Snow accretion suppression shape of snow-accreted body>
Further, according to the present invention, it is possible to provide an appropriate shape of the snow-attached body 20, specifically the shape of the snow-attached surface 20a, for suppressing snow accretion based on the above snow accretion test results. can.

As described above, the reference speed at the edge of the snow-attached surface 20a of the snow-attached body 20 is uniquely determined according to the snow quality. Then, from the reference speed, the relationship between the wind speed of the airflow F and the reference angle is calculated, and the snow accretion shape for the snow-covered surface 20a is predicted. Therefore, based on such knowledge, by forming in advance the snow-covering surface 20a of the snow-covering body 20 in the predicted snow-covering shape, more specifically, the direction of the snow-covering surface 20a and the airflow F By forming the snow-receiving body 20 such that the angle with respect to the orthogonal direction is the reference angle in advance, snow accretion on the snow-receiving surface 20a can be suppressed.

Further, as described above, the snow accretion angle φ with respect to the snow-accreted body 20 decreases as the wind speed of the airflow F increases. Therefore, a reference angle ψ allowed under the installation environment of the snow-attached object 20 is determined in advance, and the snow-attached object having the snow-attached surface 20a having an angle equal to or larger than the reference angle ψ with respect to the airflow F is determined. 20 is formed. As a result, snow accretion can be appropriately suppressed even when the wind speed of the airflow F increases.

The snow accretion shape on the snow accreted surface 20a changes depending on the wind direction angle θ of the airflow F and the wind speed as described above. That is, the snow accretion suppression shape of the snow-accreted body 20 according to the present invention is particularly useful in an environment where the wind direction angle θ of the airflow F and the wind speed are constant. Specifically, the snow accretion suppression shape according to the present invention can be applied to the shapes of trains and automobiles that are assumed to travel at a predetermined speed in a predetermined direction. Further, for example, by applying the snow accretion suppression shape according to the present invention to a bogie cover of a train, which requires cost to remove adhering snow, the cost for removing snow can be reduced.

Further, for example, by forming the train and the bogie cover in a predicted shape of snow accretion according to the lowest running speed in the running section of the train where snow accretion is expected at least, the running section where snow accretion is expected. Snow accretion can be appropriately suppressed in all of the above.

Note that the application example of the snow accretion suppression shape according to the present invention is not limited to this. In addition to the application examples described above, if the object to be covered with snow moves at a predetermined speed and in a predetermined direction, snow accretion on the object to be covered with snow can be appropriately suppressed.

Although the preferred embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to such examples. It is obvious that a person skilled in the art can conceive various modifications or modifications within the scope of the idea described in the claims, and these naturally belong to the technical scope of the present invention. accepted as a thing.

For example, in the above description, the relationship between the wind velocity U of the airflow F determined according to the snow quality and the reference angle ψ was derived from the snow accretion test of the snow accretion device 1 described above, but the derivation method is not limited to this. . For example, it may be derived by calculating the snow accretion shape for the snow accreted body using a particle simulator. Further, for example, by actually measuring the shape of snow accretion on a snow-covering object during snowfall, the measured values may be derived in a data table.

INDUSTRIAL APPLICABILITY The present invention is useful in predicting the shape of snow accretion on a snow-covered body, and is also useful in developing the shape of the snow-clad body based on the predicted shape of snow accretion.

1 snow accretion device 10 test object 10a snow accretion surface 10s reference surface 11 blower 12 snow supply unit 13 holding unit 14 camera 20 snow accretion object F air flow F' test air flow S snow S' snow sample Sa snow surface θ wind direction angle φ Snow accretion angle ψ Reference angle

Claims (4)

A snow accretion shape prediction method for a snow accreted body,
Based on the reference speed of the airflow in the snow accretion tangential direction at the end of the snow-applied surface of the snow-adhering body, which is predetermined according to the snow quality, the airflow at the end according to the speed of the airflow. calculating a reference angle that is the angle between the tangential direction of the snow and the orthogonal direction of the airflow;
The cross-sectional shape of the snow accretion is predicted as the reference angle formed by the tangential direction of the accretion of snow at the end and the orthogonal direction of the airflow in the steady state of the accretion of snow. Snow shape prediction method. 2. The method for predicting the shape of snow accretion according to claim 1, wherein the snow-covered surface is a surface included in a projection range of the airflow on the snow-covered body. 3. A snow accretion shape prediction method according to claim 1 or 2, wherein a relationship between said snow quality, said airflow velocity and said reference angle is derived in advance before predicting said cross-sectional shape of said snow accretion. . The snow accretion shape prediction method according to any one of claims 1 to 3, wherein the snow quality is determined by the water content and particle shape of the snow.

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