JP2971235B2 - Balance device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a balance device for measuring the surface frictional resistance of an object to be measured (hereinafter referred to as a "test sample").

[0002]

2. Description of the Related Art The surface of an object generates frictional resistance against the flow of air or the like. In order to reduce such frictional resistance, a riblet (small groove) or LEBU (Large)
Eddy Break up Device) may be provided. In order to measure these effects, a balance device for measuring frictional resistance has conventionally been used.

FIGS. 6A, 6B and 6C are views showing a conventional example of such a balance apparatus. That is, a rectangular plate-shaped specimen 3 is fitted into the opening 2 provided in the upper wall 1 of the wind tunnel with a slight gap around it. The surface of the test piece 3, that is, the surface to be measured 6 is the same as the lower surface 7 of the wind tunnel upper wall 1 by four piano wires 5 a to 5 d from the ceiling 4 located above the wind tunnel upper wall 1. It is suspended so that it is located in a plane. Further, a load cell 9 is installed in the upper portion 8 of the wind tunnel upper wall 1 on the upstream side of the airflow indicated by the arrow M, and the load cell 9 is connected to the upper surface of the specimen 3 by a wire 10.

Thus, a fluid such as air is caused to flow in the wind tunnel in the direction indicated by the solid arrow M in the drawing, and the surface frictional resistance of the specimen 3 against the flow of air at that time is measured by the load cell 9 via the wire 10. I was measuring.

[0005]

In the above-mentioned conventional balance apparatus, the length of the piano wires 5a to 5d is relatively long, and the test piece 3 is simply suspended. Outside the movement along the direction of air flow in the horizontal plane,
The horizontal direction orthogonal to the flow of the air flow, that is, FIG.
In the direction of the solid arrow N. Therefore, a force other than the flow direction component of the airflow applied to the specimen 3 is measured by the load cell 9, and both ends of the specimen 3 hit the end surfaces 11 and 12 of the opening 2, so that accurate measurement cannot be performed. There was a problem. Therefore, an object of the present invention is to provide a balance device that can accurately measure only a force component in a direction along a flow of a fluid such as air applied to a specimen.

[0006]

Means for Solving the Problems In order to solve the above problems and achieve the object, the present invention takes the following measures. That is, a support mechanism for supporting the object to be measured such that the inner wall surface and the surface of the object to be measured are located in the same plane at an opening provided in a part of the inner wall surface of the wind tunnel; A measuring means for measuring a force in a direction along a flow of a fluid in a wind tunnel acting on the support mechanism, wherein the support mechanism can slide the object to be measured only along a flow direction of the fluid. The air slider was provided with such a support.

[0007]

The following effects are obtained as a result of taking the above measures. The air slider supporting the specimen can move only in the axial direction, and does not move in the direction perpendicular to the axial direction.
The object to be measured can be supported by the air slider so as to be slidable only in the fluid flow direction, and only the force component applied to the specimen in the fluid flow direction can be accurately measured.

[0008]

1 and 2 (a) and (b) show a balance apparatus according to a first embodiment of the present invention. In these figures, the same parts as those shown in FIG. 6 are denoted by the same reference numerals, and description of overlapping parts will be omitted.

The main difference between the balance apparatus according to the first embodiment and the conventional balance apparatus lies in the structure for supporting the specimen 3. That is, in this embodiment, the air sliders 20a to 20d, that is, the air bearings are used to support the specimen 3. The air sliders 20 a to 20 d are arranged around a rectangular opening 2 provided in the upper wall 1 of the wind tunnel. Of these air sliders 20a to 20d, the structure of the air slider 20a is shown as a representative.
It is configured as shown in FIG.

In FIG. 1, reference numeral 21 denotes a fixed body.
The fixed body 21 includes a frame 22, an air guide plate 23 provided inside the frame 22, and a columnar cavity 24 provided so as to penetrate substantially the center of the air guide plate 23. It is configured. In the columnar cavity 24, a movable body 25 formed in a columnar shape is movably arranged along the axial direction of the columnar cavity 24.

The air slider 20a constructed as described above
, High-pressure air is supplied from a high-pressure air supply device 26 shown in FIG. 1 through an air hose 27a. Thus, the movable body 25 is levitated by filling the gap between the air guide plate 23 and the movable body 25 with high-pressure air. At this time, since the gap between the air guide plate 23 and the movable body 25 is kept at a fixed interval, the movable body 25 is
It cannot move in the direction, that is, the direction perpendicular to the axial direction. Therefore, the movable body 25a can freely move only in the direction of the solid arrow Z in the drawing, that is, only in the axial direction.

Returning to FIGS. 1 and 2 (a) and (b).
The air sliders 20a and 20b are arranged on the upstream side of the opening 2, and the air sliders 20c and 20d are arranged on the downstream side of the opening 2. Here, sliders 20a-20
d is arranged in such a direction that the axial directions of the movable bodies 25a to 25d are all parallel, and the movable bodies 25a to 25d
Specimen 3 is fixed to the tip of. 28 is a wire, 2
9 is a force measurement sensor.

In the embodiment constructed as described above, the high-pressure air supply device 2 is connected to the air sliders 20a to 20d.
When the high-pressure air is supplied from 6, the movable bodies 25a to 25d float, and the specimen 3 is positioned at a predetermined position, that is, the lower surface 6 of the specimen 3 is located on the same plane as the inner wall surface 7 of the wind tunnel upper wall 1. Supported. Subsequently, air is allowed to flow through the wind tunnel in the direction indicated by the solid arrow M in the figure, and the force acting on the specimen 3 due to frictional resistance with the air is transmitted through the wire 28 to the force measurement sensor 2.
Measured by 9.

As described above, in the present embodiment, since the specimen 3 is regulated so as to be displaced only in one direction, that is, only in the direction of air flow, the force component of the air flow applied to the specimen 3 only in the direction of air flow. Is measured with high accuracy.

FIGS. 4 and 5A and 5B show a balance apparatus according to a second embodiment of the present invention. In these figures, the same parts as those shown in FIGS. 1 and 2A and 2B are denoted by the same reference numerals, and the description of the overlapping parts will be omitted.

The second embodiment differs from the first embodiment in that the specimen 33 is a disk having a predetermined curvature on its surface. That is, the specimen 33 having a shape that forms a part of a spherical shell has a slight gap around the opening 32 provided in the wind tunnel upper wall 31 having the same curvature as the specimen 33. It is embedded. The specimen 33 is supported by air sliders 20a to 20d arranged around the opening 32, as in the first embodiment. Also in this embodiment, the sliders 20a to 20d
The specimens 33 are fixed to the ends of the movable bodies 25a to 25d so that the axial directions of a to 25d are all parallel.

In the embodiment constructed as described above, the high-pressure air supply device 2 is provided to the air sliders 20a to 20d.
When the high-pressure air is supplied from 6, the movable bodies 25a to 25d float, and the specimen 33 is moved to a predetermined position, that is, the specimen 33
Is supported such that the lower surface 36 is located within the same curved surface as the inner wall surface 37 of the wind tunnel upper wall 31.

As described above, also in this embodiment, the specimen 33 is restricted so as to be displaced in only one direction, that is, only in the direction of air flow, as in the first embodiment.
The force component only in the direction of flow of the airflow applied to 3 is measured with high accuracy. It should be noted that the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0019]

According to the present invention, since the displacement direction of the specimen is regulated so as to be displaced only in the direction of flow of the fluid, the force component applied only to the direction of flow of the fluid applied to the specimen can be accurately detected. Can be measured.

In addition, since the specimen does not move in the direction perpendicular to the axial direction of the air slider, the specimen enters the opening of the wind tunnel, and the fluid hits the end face of the specimen and an extra force is applied to the force measuring sensor. Can be avoided, and the accuracy of the measured value can be further improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing the configuration of a balance device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the embodiment taken along lines 2A-2A and 2B-2B in FIG. 1 and viewed in the direction of the arrows;

FIG. 3 is a perspective view and a cross-sectional view showing a configuration of the air slider of the embodiment.

FIG. 4 is a plan view showing a configuration of a balance device according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view taken along the line 5A-5A and the line 5B-5B of FIG.

FIG. 6 is a plan view and a cross-sectional view of a main part of a conventional balance device.

[Explanation of symbols]

1, 31: wind tunnel, 2, 32: opening, 3, 33: specimen, 20a-20
d: air slider, 21: fixed body,
25a to 25d: movable body, 26: high-pressure air supply device,
27a-27d ... air hose.

Claims (1)

(57) [Claims] 1. A balance device for measuring a force (surface friction resistance) of a fluid acting on a surface of an object to be measured, comprising: an opening provided in a part of an inner wall surface of a wind tunnel; A support mechanism for supporting the object to be measured so that its surface is located in the same plane as the inner wall surface of the wind tunnel, and a flow of fluid in the wind tunnel acting on the object to be measured supported by the support mechanism. Measuring means for measuring a force in a direction, wherein the support mechanism includes an air slider which supports the object to be measured so as to be slidable only along a flow direction of the fluid. apparatus.