JPS6031413A - Windbreak fence - Google Patents

Abstract

PURPOSE:To obtain a windbreak fence of high wind shield efficiency by providing two screen nets which have the same meshes and are arranged in parallel with each other and forming said meshes in such a manner as the apparent completeness rate of the wind shield face side of the fence, formed by both nets, comes to a predetermined value. CONSTITUTION:The captioned windbreak fence, used for prevention or the like of dispersion of coal dust in an outdoor coal depot or the like, is formed by fitting panel constituent bodies 3 between struts, erected at predetermined intervals, so as to be continued vertically and right and left. The panel constituent body 3 is formed by stretching rectangular nets 2, 2' on both sides of a pair of upper and lower interval maintaining members 5, 5 and fixing said nets by means of holding members 6, 7 provided along their edge parts. Further, the nets 2, 2' are formed in such a manner as their meshes zigzag in longitudinal and lateral directions with each other and the apparent completeness rate, on the wind shield face side of the fence formed by both nets, is 50-80%. Further, an interval L between the nets 2, 2' is set above 2mm. and within 5 times the lateral length lof an opening part of the meshes.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a windbreak fence used to prevent scattering of coal dust from the surface of coal storage in outdoor storage areas such as thermal power plants, etc., and relates to a fence with extremely high wind blocking effect. It is.

In the above-mentioned coal storage yard, etc., as shown in Figure 1, Yamagata + c [
Dust that is blown up and scattered by strong winds from the surface of the raised coal storage (1) falls outside the coal storage area and contaminates the surrounding area.
This has become a problem.

Windbreak fences, for example, are useful in addressing such problems. A fence (8) is installed on the windward side of the coal storage (1).
) to block the wind from blowing in.

However, windbreak fences have the following problems.

In other words, the wind-shielding effect of a fence is, theoretically, as shown in the schematic explanatory diagram in Figure 2, when separation (C) is generated in the wind flow 0) by the upper end of the fence (8), and the separation is A so-called dead zone (hatched area) is formed below the flow of water at a zero wind speed line.

However, in reality, if a simple screen-like object is used as a fence, many strong eddies will occur in the dead area, especially near the fence, and the theoretical dead area is not a sufficient wind speed reduction area. It is impossible.

The inventor of the present invention intended to develop a windbreak fence that can eliminate the eddies in the dead water area and secure the dead water area as a sufficient wind speed reduction area, and as a result of extensive experiments and research, the following findings were made. I found laughter. That is, as mentioned above, when a fence is installed, the strong vortex that is generated on the leeward side of the fence can be made weaker and smaller δ by making the fence itself into a net shape than vc. In other words, with a net fence, this is the result of the wind blowing through the fence acting on the vortices on the leeward side of the fence. However, even in the case of this net fence, it is virtually impossible to achieve both the effect of suppressing vortices on the leeward side of the fence and the original wind-shielding effect, that is, the effect of ignoring the effect of vortices and reducing the wind speed. be. In other words, in the case of a net fence, the conditions of the VC mesh greatly influence the flow on the leeward side of the fence.

Specifically, the percentage of fullness of the fence surface and the ratio of the full part of the fence to the visible area of the fence are the major influencing factors, and if this percentage of fullness is small, the formation of vortices on the leeward side of the fence tends to be suppressed. Although the effect is high, the wind shielding effect is poor.On the other hand, when the filling rate is high, the wind shielding effect itself is good, but the vortex formation is strong and large, and the dead water immediately on the lee side of the fence ends up being The area's wind speed reduction ratio becomes lower. Because of this relationship, even in the case of a net fence, it is difficult to secure a sufficient wind speed reduction area on the leeward side of the fence.

However, in this net fence, the net has a so-called double-strung structure, and as shown in Figure 3, the mesh between both nets (2J (2)) is arranged in both the vertical and horizontal directions. By arranging them in a staggered manner, it is possible to simultaneously secure an excellent wind-shielding effect and an effect of suppressing vortices in the dead water area.In other words, this double-walled net fence has a substantial appearance on the fence surface. ratio, that is, the fence area and both nets (21(2'
) is the most important factor that influences the flow on the leeward side of the fence. This is similar to the case of the single-layer net fence described in . That is, when the filling ratio is small, the wind blocking effect is poor, and when it becomes large, the rectifying effect of the fence in the vicinity of the leeward monk 1 is reduced. However, in the case of double-walled panels, unlike single-walled panels, it is possible to achieve both wind-shielding and flow-straightening effects at a high level, ensuring an excellent rectifying effect while maintaining a high wind-blocking effect. There is a region of apparent enrichment rate. this is,
When wind passes through a double-strung fence, it passes through the net twice, and at that time, the net functions as a so-called rectifying grid, and at the same time breaks up large turbulent vortices into smaller pieces. It is thought that this is to exert a heavy effect [to become]. For this reason, in the case of a double-hung net fence, it is possible to ensure wind speed reduction that is wide 1lIIIvc downwind of the fence and has a sufficient wind speed reduction ratio.

That is, the present invention is based on the above, and the same mesh shape is also provided by two screen nets arranged parallel to each other (2J
(2') by 10Hf, both nets have vertical meshes,
The fence is located in a staggered pattern in both horizontal directions, and the apparent fullness rate of the wind-shielding surface of the fence consisting of both nets is 50 to 8.
0%, and the distance between the two nets (g) is at least double and is within 5 times the same horizontal length of the mesh opening (6). .

In the present invention, the positional relationship of the meshes of the double-walled nets is staggered in both the vertical and horizontal directions as shown in Figure 3, and the tiles are made to function well as a rectifying grid with the double-walled nets. This is to enable effective elimination of the vortices immediately on the leeward side of the fence.

Next, the reason why the apparent fullness of the fence surface of the fence body made of this double-layered net was limited to 50 to 80% is because if it is less than 50%, the wind blocking effect will be insufficient.
This results in an insufficient wind speed reduction ratio on the leeward side of the fence, and conversely, with a high filling rate exceeding 80%, sufficient rectification cannot be achieved on the leeward side of the fence, which poses a problem. Note that this apparent enrichment rate is preferably about 55 to 65% in terms of effectiveness.

Furthermore, the mutual separation distance [Yes] of the double tensioned υ net shown in Figure 3 (B) (longitudinal side view) is set to be 211 or more and the horizontal feldspar (to) of the mesh opening (Figure 3 (A)) is set to 211 or more. The reason why we set it within 5 times of L (reference) is that L (2mm is functionally almost the same as a single-layered net, so there is no real meaning in making it double-layered.
This is because when r, shi and L>5A, the mutual interference effect disappears.

As the net for the double-walled net fence of the present invention, any net can be used regardless of the shape of the mesh, thick awn, etc., as long as it can secure the above-mentioned apparent fullness rate of 50 to 80%. be. In short, no matter which net you use, you can always expect the same effect as long as you ensure that the apparent fullness of the fence is 50-80%. (2+, (2') shown in FIG. 3)
) is a so-called expanded metal type made by making slits in a single plate and expanding it, and this Ekinu Bando Metal type 5 is the most common type of metal net.

Specifically, the fence of the present invention is constructed as shown in FIG. 4, for example. That is, in the same figure, the Fuenne body (
4) is a panel structure using the above net (
A large number of fences (3) are installed in a continuous manner vertically, horizontally, and vertically between posts (4) erected at predetermined intervals at the fence installation site. The above panel structure (3) is:
For example, as shown in Figure 5 ((a) is a front view, (b) is a side view) K, there is a spacing member (5) made of a pair of upper and lower channel steel.
Rectangular nets (2) (2) are stretched on both sides of (5) and fixed with press members (6) (7) arranged along the edges to form a panel shape.

Next, an experiment conducted to confirm the effectiveness of the fence of the present invention will be described.

A wind tunnel experiment was conducted using an Elafel-type blowout boundary layer wind tunnel using the following five net fence models.

Fence model Note) &8 is the apparent enrichment rate. No. 8 is a double-layered net fence based on the present invention. The experiment was conducted as follows.

(2) A model fence is installed in the wind tunnel perpendicular to the main wind direction in the wind tunnel, and air is blown. The airflow in the wind tunnel is a uniform turbulent flow with a turbulence component given by a turbulence grid, and the wind speed is 500 MM (
IOmj/BBc at the height of the boundary layer.

■ While air is being blown, the wind speed is measured using a constant temperature hot wire anemometer at each of a number of measurement points set on a vertical plane passing through the wind tunnel center line (fence center line) and parallel to the main wind direction. .

[Phase] For each measurement point, after linearizing the output of the constant temperature hot wire anemometer with a linearizer,

Digital with a ring interval of 0.01 seconds and a duration of 10 seconds/
"Convert it into a quantity, calculate its average value (, The standard deviation of the wind speed fluctuation, /F, is the high δ500 of the III C boundary layer.
) is nondimensionalized by the average wind speed Urzoo of the approaching flow, F/Ur. Each is expressed in the form of 0, so-called strong disturbance.

The results of the experiment are shown in FIGS. 6 and 7. Figure 6 shows the vertical distribution of the wind speed ratio TJ/Dr, and Figure 7 shows the vertical distribution at strong turbulence. )...Fall.

(0)...fall 2. (c)...No.3. In both figures, the vertical axis shows the height and the position, the horizontal axis shows the position in the main wind direction, and the vertical axis shows the height from the wind tunnel floor. (4) Increase the height of the fence)
(=20011-) and the horizontal axis is the distance (X) taken from the fence position as a reference (the main wind direction is positive and the opposite direction is negative). (Takaishi) to make it dimensionless and calculate LX/h by taking each of them. The wind speed distribution in Figure 6 shows how many times the wind speed at a certain height is than the wind speed of the approaching flow, and the turbulence distribution in Figure 7 shows the strength of separation of the flow from the top of the fence. It is something that can be done. For ease of understanding, in Figure 6: u is the area where the wind speed ratio is 0.6 or less as a sufficient wind speed reduction area, and in Figure 7, turbulence strength is used as an indicator of the strength of separation. The portions above 0°1 are shown with hatching.

From the results in both figures, the following can be said. Regarding the one-ply fence, is it a fence model? In case of a small V-filling ratio such as 1b1, the separation of the sag from the upper end of the fence becomes weak, and the wind speed on the leeward side of the fence cannot be sufficiently reduced. Similarly, when the charging rate is set high as in case 2, the overall wind speed reduction ratio on the leeward side of the fence will be high, but the turbulence strength immediately on the leeward side of the fence will also be large, and sufficient wind speed reduction will not be achieved in this area. I can't hope. It goes without saying that the turbulence is strong and large, which means that there is a risk that the maximum instantaneous wind speed will increase due to the large wind speed opening and movement.

On the other hand, the double 'J-
With fence No. 9, the turbulence immediately on the leeward side of the fence can be effectively eliminated, and the wind speed on the leeward side of the fence can also be sufficiently reduced.

Incidentally, in the experiment, the airflow in the wind tunnel was a uniform turbulent flow with a turbulent component given by the turbulence grid as described above, but a slight boundary layer was observed to form in the vertical wind speed distribution in the fire pit. Its power exponent is α'/10. It was a.

According to many results from the East, the atmospheric boundary layer in coastal areas and other open areas has a power index of 1/10≦α≦7, and therefore the wind tunnel air flow used in the experiment is the same as the current level in open areas. It can be seen as a general reproduction of the atmospheric boundary layer, and from this it can be recognized that the above experimental results are similar to the situation of a fire pit.

As is clear from the above description, the windbreak fence of the present invention is capable of securing a wide wind speed reduction area on the leeward side of the fence and having a sufficient wind speed reduction ratio. It can exhibit excellent effects in preventing the scattering of water and protecting agricultural crops.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing an example of how a fence is used in an outdoor coal storage yard, Figure 2 is a diagram illustrating the wind blocking effect of a fence, and Figure 3 is an explanatory diagram showing an example of the use of a fence in an outdoor coal storage yard.
The figure shows an example of the double-layered net of the fence of the present invention, (
A) is a front view, (o) u vertical r! fr side view. FIG. 4 shows a specific example of the overall structure of the fence of the present invention, in which (a) is a front view and (b) is a longitudinal side view. FIG. 5 shows a panel structure used in the fence according to the present invention, in which (a) is a front view and (b) is a side view. Figures 6 and 7 show the results of wind tunnel experiments regarding various types of fences. Figure 6 is a vertical distribution diagram of wind speed, and Figure 7 is a vertical distribution diagram of turbulence intensity. In the figure, l: coal storage, 2, 2: net, 3: panel structure,
4: Strut, 5: Spacing member, 6.7: Holding member Applicant: Sumikin Kozai Koushiba Co., Ltd. 5 Figure 1 Figure 1 Figure 2 Figure 6 Figure C) 12/8.1 1 person/Ml

Claims (1)

[Claims] (1) Two screen nets (2J (2')) arranged parallel to each other with the same mesh shape, both of which are located so that the meshes of each other are staggered in both the vertical and horizontal directions. The apparent fullness rate on the wind-blocking surface side of the fence body formed by netting δ is 50 to 80%, and the gap between both nets is 2.
A windbreak fence characterized in that the width is greater than or equal to 5 times the lateral length δ(a) of the mesh opening.