Porous plate, and blade suction device

Abstract

To save power of suction in consideration of pressure loss in a suction plate having micropores.SOLUTION: There is provided a suction plate where a plurality of micropores are provided, wherein the micropores penetrate into the other surface as an outflow side of the suction plate from one surface as an inflow side thereof, and are formed so that the diameter of the opening on the one surface side is larger than the smallest diameter of the micropores.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a device for aspirating disturbances in the boundary layer formed on the surface of an aircraft wing. [Background technology]

[0002] For example, Patent Documents 1 to 5 disclose sucking in disturbances in the boundary layer formed on the surface of an aircraft wing using minute holes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2012-515117 [Patent Document 2] JP 2009-102007 A [Patent Document 3] Special Publication No. 2003-503263 [Patent Document 4] Japanese Patent Application Publication No. 07-108996 [Patent Document 5] Japanese Patent Application Publication No. 02-164696 Summary of the Invention [Problem to be solved by the invention]

[0004] In such a device that realizes a uniform suction area over a wide area of ​​the device surface by arranging micro-holes, the fluid is sucked through the micro-holes by an aspirator such as a vacuum pump inside the device. On the other hand, since it is necessary to make the fluid flow through the micro-holes, the aspirator needs a certain level of power, and saving this power becomes an issue. No research has been done to date on pressure loss, which is one factor in saving power.

[0005] Therefore, an object of the present invention is to reduce the power required for suction by taking into consideration the pressure loss in a suction plate having minute holes. [Means for solving the problem]

[0006] The inventors have conducted extensive research into reducing the pressure loss and the power required for suction, and have found that a "microhole" is a hole through which a fluid is sucked in, where the fluid velocity inside the hole is several times faster than before the fluid enters the hole, and where a large pressure loss occurs due to the viscosity of the fluid, and that by making the diameter of the microhole larger on the inlet side and smaller on the outlet side, it is possible to alleviate the pressure loss occurring in the microhole and greatly reduce the power required for suction. The inventors have then realized this and completed the present invention.

[0007] The present application discloses a suction plate having a plurality of microholes formed therein, the microholes penetrating from one surface of the suction plate which is the inflow side to the other surface which is the outflow side, and the diameter of the opening on one surface side being formed larger than the smallest diameter of the microholes.

[0008] The portion of the opening and the portion of the smallest diameter may be connected by a curved or inclined surface.

[0009] The opening may be formed so that the diameter is 1.5 to 2.0 times the smallest diameter.

[0010] The present application discloses a wing suction device in which the above-mentioned suction plate is provided on the surface of the wing. Effect of the Invention

[0011] According to the present disclosure, the pressure loss in the suction plate having a plurality of microscopic holes can be reduced, and the power required for suction can be reduced, thereby making it possible to save labor. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic cross-sectional view of a blade 1. As shown in FIG. [Diagram 2] FIG. 2 is a cross-sectional view showing a schematic configuration of the wing suction device 10. As shown in FIG. [Diagram 3] FIG. 3 is a plan view showing a part of the suction plate 20. As shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view illustrating the microhole 21. As shown in FIG. [Diagram 5] FIG. 5 is a cross-sectional view illustrating another embodiment of the microholes 21. As shown in FIG. [Figure 6] FIG. 6 shows the results of the test example. [Figure 7] FIG. 7 is a pressure contour diagram of a test example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] 1 is a cross-sectional view conceptually showing a blade 1 equipped with a blade suction device 10 (including a suction plate 20) according to one embodiment. The blade suction device 10 is provided on the blade in this manner to suck in turbulence in the boundary layer formed on the blade surface, thereby reducing resistance on the blade 1.

[0014] Fig. 2 is a cross-sectional view showing a schematic configuration of the blade suction device 10 by enlarging the portion indicated by A in Fig. 1. The blade suction device 10 has a suction plate 20, one side of which (first side, outer side 20a) forms the surface of the blade 1, and the other side (second side, inner side 20b) is provided with plenum chambers 11, which are spaces partitioned at regular intervals, and each plenum chamber 11 is connected to a suction pipe 12. The suction pipes 12 are connected to a suction pump (aspirator) not shown. The suction plate 20 is provided with a plurality of minute holes 21 penetrating from the outer surface 20a to the inner surface 20b. As a result, when the suction pump begins to suck in air, the disturbances in the boundary layer formed on the outer surface 20a of the suction plate 20 (the outer surface of the blade 1) are sucked in through each of the multiple micro-holes 21, join together in the plenum chamber 11, and are discharged to the outside by the suction pump through the suction pipe 12.

[0015] FIG. 3 shows a plan view of a part of the suction plate 20, and FIG. 4 shows a BB cross-sectional view focusing on one of the microholes 21. As shown in FIG. As can be seen from Figures 2 to 4, a plurality of microholes 21 are arranged in the suction plate 20. As can be seen from Figure 3, in this embodiment, the plurality of microholes 21 are arranged at the vertices of an equilateral triangle. This makes it possible to increase the degree of uniformity of gas suction on the blade surface. However, the arrangement is not limited to the vertices of an equilateral triangle, and may be at the vertices of a rectangle. Furthermore, the arrangement pattern of the microholes 21 may be changed depending on the position in order to increase the uniformity of gas suction.

[0016] 3 is not particularly limited, if the interval P between the adjacent microholes 21 is too narrow, non-uniform suction will occur on the upstream side of the microholes 21, and if the interval P between the microholes 21 is too wide, the flow downstream of the microholes 21 will fluctuate with time and become unstable. From this perspective, the size of the interval P is preferably 5 to 10 times the inner diameter (diameter D2) of the microhole 21. Further, in this embodiment, the interval P is constant, but this is not limiting, and the interval between the minute holes 21 may be changed depending on the position in order to improve the uniformity of the gas intake.

[0017] Focusing on one minute hole 21, as shown in cross section in FIG. 4, it has the following characteristics. Regarding the diameter of the microholes 21, when the diameter of the smallest diameter portion of the microholes 21 is D2, the diameter D1 of the opening on the outer surface 20a is larger than the diameter D2. This reduces the pressure loss in the microholes 21, and saves the labor required for gas suction. The difference between the diameters D1 and D2 is not particularly limited, but if the difference is too small, the effect of reducing pressure loss will be small, and if the difference is too large, small objects such as small insects and dust will be easily sucked in, increasing the possibility of blocking the micropores. From this perspective, the ratio D1 / D2 is preferably 1.5 to 2.0.

[0018] In this embodiment, the surface connecting the opening with diameter D1 on the outer surface 20a and the portion of the microhole 21 with diameter D2, which is the smallest diameter, is a curved surface (arc-shaped) that is convex toward the inside of the microhole 21. This makes the flow of the fluid flowing along the wall surface of the microhole 21 smoother, and the effect of reducing pressure loss becomes more pronounced. However, this is not limited to this, and it may be an inclined surface (tapered) as shown in Figure 5(a) or a step (step-shaped) as shown in Figure 5(b).

[0019] The specific size of each part constituting the microhole 21 is not particularly limited as long as it can be used as a microhole applied to the suction plate of the blade suction device, but the size of the diameter D2 can be 30 μm to 100 μm. Similarly, the axial length T1 of the microhole 21 (plate thickness of the suction plate) can be 500 μm to 1 mm. In addition, the axial length T2 of the part of T1 other than the part with diameter D2 (range of the part with diameter larger than diameter D2) is preferably 0.03 to 0.2 in terms of the ratio represented by T2 / T1.

[0020] As a test example, a simulation was performed when a microhole was formed following the example in Fig. 4. In the simulation, the microhole had T1 of 0.7 mm, D2 of 0.055 mm, and P of 0.565 mm. The radius of the arc of the curved surface indicated by R in Fig. 4 was changed to 0 μm, 13.75 μm, 27.5 μm, and 55 μm, thereby changing the diameter D1 of the opening on the upper surface 20a. Using this model, we calculated the change in pressure in the axial direction of the microhole. The results are shown in Figure 6. In Figure 6, the horizontal axis represents the axial position of the microhole, and the vertical axis represents the pressure. Here, the microhole is in the range of 0 mm to 0.7 mm on the horizontal axis. The suction speed of the fluid into the suction plate was set to 25 cm / s.

[0021] As can be seen from Figure 6, the smaller R is, the larger the change in pressure is, especially at the entrance of the microhole (near 0 mm on the horizontal axis), which means that the pressure loss is large. In other words, by adding R (making diameter D1 larger than diameter D2), the pressure loss can be reduced, and the power required to draw in the gas can be saved. FIG. 7 shows a pressure contour diagram (1 / 2 model (near the inlet) with the axis of the microhole at O). FIG. 7(a) shows R=0 μm, and FIG. 7(b) shows R=55 μm. It can also be seen from this diagram that by making diameter D1 larger than diameter D2, the pressure change becomes more gradual, reducing pressure loss and enabling the power required to suck in gas to be saved. According to the inventor's calculations, by setting R=55 μm, a 12% reduction in pressure loss was observed compared to when R=0 μm. This reduction in pressure loss leads to a reduction in the power required for the suction pump, making it possible to save power. [Explanation of symbols]

[0022] 1...Blade, 10...Blade suction device, 11...Plenum chamber, 12...Suction tube, 20...Suction plate, 21...Minor hole

Claims

1. A suction plate having a plurality of micro holes, The microholes penetrate from one surface of the suction plate which is an inflow side to the other surface which is an outflow side, and are formed so that the diameter of the opening on the one surface side is larger than the smallest diameter of the microholes. suction board.

2. The suction plate according to claim 1 , wherein the opening portion and the portion with the smallest diameter are connected by a curved surface or an inclined surface.

3. 2. The suction plate according to claim 1, wherein the diameter of the opening is 1.5 to 2.0 times the smallest diameter.

4. A blade suction device comprising the suction plate according to any one of claims 1 to 3 provided on a surface of a blade.

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