JPH0961288A - Balance for wind tunnel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wind tunnel balance wherein the response of a balance output can be secured, the balance is highly rigid, vibration output waveforms with multiple frequencies can be obtained, and highly accurate data can be obtained even with a wind tunnel test with short ventilation time. SOLUTION: A plurality 31, 32 of measuring parts 3 interposed between an outer cylinder 2 fitted over a sample to be integrated with the sample and a cylinder 1 fitted over a tip of a sting 04 for supporting the sample at a predetermined position in a wind tunnel and integrated with it for sensing deformation caused by load applied to the sample for detecting the aerodynamic load are provided separately from a center of a balance in an X-axis direction. This five-component force of the sample except a load Fx in the X-axis direction of the sample can be detected by tensile and compressive deformation caused on the front and rear measuring parts 31, 32, so that measurement accuracy of Fx with a small output can be improved, while balance rigidity can be increased thereby obtaining vibration outputs with multiple frequencies in a short time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can be used as an aerodynamic force measuring device in a normal wind tunnel test with a relatively long ventilation time, or as a general load or impact force measuring device, and moreover, it can be used for a high temperature shock wind tunnel or the like. Ventilation time 1-2 msec
Application of a wind tunnel test of a very short degree to an aerodynamic force measuring device relates to a suitable wind tunnel balance.

[0002]

2. Description of the Related Art Specimen installed in a wind tunnel (wind tunnel model)
In a wind tunnel balance that measures the aerodynamic force acting on the wind tunnel, especially in a wind tunnel test with a short ventilation time, such as an impact wind tunnel, it is necessary to measure the aerodynamic load applied to the specimen instantaneously. Further, in such a wind tunnel test, the specimen and its supporting device generate vibration due to an aerodynamic load applied instantaneously, and the wind tunnel balance for measuring the aerodynamic load applied to the specimen is shown in FIG. It produces a sinusoidal vibration output as shown. Therefore, in such a wind tunnel test, the output of this sinusoidal vibration period is generated as much as possible within the available ventilation time of the wind tunnel, and the output results are averaged to obtain a steady state on the test piece. I try to find the aerodynamic force to be applied.

FIG. 5 is a view showing the structure of a multi-force balance as an example of a wind tunnel balance that has been conventionally used in such a wind tunnel test. 5A is a plan view, FIG. 5B is a cross-sectional view taken along the line EE of FIG. 5A, and FIG. 5C is a view taken along the line FF of FIG. Side sectional view, FIG.
FIG. 6D is a cross-sectional view taken along the line GG of FIG. 5C, which is a measurement unit.

As shown in the figure, in such a wind tunnel balance, a test piece 20 as shown in FIG. 2, which is an embodiment of the present invention, is arranged and supported at a predetermined measurement position in the wind tunnel. An opening is provided at the front end of the sting 04, and a taper portion at the rear end is inserted into a hole 011 coaxially formed in the sting 04 to be integrated with the sting 04. An opening is provided in the rear part of the test piece 20, and a model mounting portion 05 is inserted into an opening of the test piece 20 formed in the axial direction of the machine body to form an outer cylinder 02 and an inner cylinder 0 integrated with the test piece 20.
The measuring unit 03 is interposed between the outer cylinder 1 and the outer cylinder 02, and the sensing unit elements 08 are arranged in parallel in only one row in the X-axis direction.

That is, the measuring portion 03 extends from the inner cylinder 01 in the Y and Z directions, and connects the cross-shaped sensing portion 06 and the outer diameter end portion of the sensing portion 06. A portion in the circumferential direction corresponding to the sensing portion 06 is cut off, and is composed of a flexible structure portion 09 that extends rearward from the outer cylinder 02 and an annular outer frame portion 07 whose front end is connected. On both side faces of the test piece 20, one row in the X-axis direction is provided at positions equidistant in the radial direction from the balance center 010 and is deformed by the aerodynamic force acting on the sample 20 fitted into the model mounting portion 05. The displacement of the sensitive part 06 is detected, and the X axis, Y axis, and Z of the sample 20 are detected.
Axial force Fx, Fy, Fz, and moments Mx, My, Mz about these axes, that is, the 6-component force of the aerodynamic load applied to the specimen 20 are attached to the sensing element 08. ing.

The sensing element 08 is arranged in the radial direction to detect the 6-component force by detecting the displacement of the sensing section 06 in the radial direction. As described above, the wind tunnel balance configured as described above is used for the specimen 20.
In order to fix the sting 04 to the sting 04 and to generate as many vibration cycle outputs as possible within the available ventilation time of the wind tunnel, it is necessary to increase rigidity and increase the natural frequency of the wind tunnel balance. Depending on the aerodynamic load of the specimen to be measured, it is necessary to make it short, thick and highly rigid within the possible range.

However, as described above, increasing the structural rigidity of the wind tunnel balance means that the amount of deformation (the amount of bending deformation) that occurs in the sensing portion 06 due to a certain amount of aerodynamic load applied to the specimen. Means that the strain amount of the sensing unit element 08 accompanying the deformation of the sensing unit 06 when a certain amount of aerodynamic load is applied to the sample becomes small, and is detected by this strain amount. There is a drawback in that the responsiveness of the output of the wind tunnel balance to the aerodynamic load, that is, the sensitivity is lowered, and the measurement accuracy is deteriorated.

In particular, among the natural vibration modes of the wind tunnel balance, those that generally correspond to the measurement of the moment around the Y-axis need to have high rigidity in order to enable measurement in a short time. Regardless, in order to measure a load (drag) with a small output in the X-axis direction of the test piece 20 that is measured at the same time as the moment about the Y-axis, high rigidity cannot be achieved and the rigidity must be the lowest. There is a strong demand to improve this.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the conventional wind tunnel balance, the present invention is directed to FIG. 5 among the aerodynamic load components applied to the specimen measured by the wind tunnel balance.
Moments about Y-axis and Z-axis, My, Mz,
While maintaining high rigidity against Y-axis and Z-axis loads, Fy, and Fz, the output of the wind tunnel balance is relatively small, and the response to aerodynamic loads may decrease.
The balance output sensitivity with respect to the axial load Fx and the moment Mx about the X axis can be adjusted in a wide range, and the natural frequencies for all aerodynamic load components can be sufficiently increased without deteriorating the measurement accuracy of these. It is an object of the present invention to provide a wind tunnel balance that can obtain a multi-cycle vibration output waveform even within a very short measurement time and can measure the aerodynamic force constantly applied to a test piece.

[0010]

For this reason, the wind tunnel balance of the present invention employs the following means. A measuring unit provided with a sensing element for detecting an aerodynamic load acting on a specimen integrated with the outer cylinder, which is arranged between the inner cylinder and the outer cylinder of the wind tunnel balance,
A plurality of them were provided in the axial direction, spaced apart from the center of the balance in the front and back. The sensing element provided in the measuring section may be arranged in the radial direction or the circumferential direction of the surface including the Y axis and the Z axis. Further, in the present invention, two or more measuring units provided separately from each other in the X-axis direction are installed. However, in order to simplify the structure and the measurement, the two measuring units are provided. May be provided equidistantly from the balance center.

In the wind tunnel balance of the present invention, by adopting the above-mentioned means, the measuring units are arranged in series in a plurality of rows at positions separated in the X-axis direction, and the moments about the Y-axis and the Z-axis are set to a single value. Detects the bending deformation of the sensing unit. The tension generated in the sensing unit elements provided in the plurality of measuring units, which are separated from the conventional detection by the bending strain of the sensing unit element, and are separated from the conventional detection. ,
The distortion in the compression direction enables detection. Generally, the moment around the Y-axis and the Z-axis, which has a low natural frequency, is detected by the strain due to the tension and compression of the sensing element as described above, so that the natural frequency is increased. it can.

The sensing section provided with the sensing element is
Since it is stronger against the load in the tensile / compression direction than the load in the bending direction, the moment around the Y-axis and Z-axis, My
, Mz, the load in the Y-axis and Z-axis directions, and the balance capacity for Fy, Fz can be set to a large value. Further, the capacity, which is the maximum measuring capacity of the balance with respect to the moments about the Y axis and the Z axis and My and Mz, can be freely set by changing the distance between the installation positions of the plurality of measuring units.

Further, with respect to the small load in the X-axis direction, which has caused the moment around the Y-axis and the natural frequency of Fy to be low, the width as the structure of the sensing section is independent. , And the length can be adjusted to a small value, and the necessary sensitivity can be secured. As a result, the bending strain for measuring the load in the X-axis direction, Fx, and the moment Fy around the Y-axis, which requires high rigidity, can be obtained. Became possible. Furthermore, since the sensing element detects the bending deformation of the sensing portion,
Conventionally, the sensing element element of the wind tunnel balance of the present invention, which is arranged only in the radial direction, is measured by pulling and compressing the front and rear measuring parts, so that it can be arranged also in the circumferential direction. , By this, the diameter of the inner cylinder that constitutes the balance for the wind tunnel can be made larger than that of the conventional one.
It is also possible to increase the rigidity of the entire wind tunnel balance.

Further, the wind tunnel balance of the present invention can be made into a machined and integrated structure capable of achieving high rigidity by adopting the above-mentioned means. The natural frequency can be made higher than that of the wind tunnel balance having a divided and combined structure.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a wind tunnel balance of the present invention will be described below with reference to the drawings. In the drawings showing the embodiment of the present invention, the same reference numerals as those shown in FIG. 5 denote the same or similar members, and the description thereof will be omitted.

FIG. 1 shows a first embodiment of the wind tunnel balance of the present invention.
1A is a front view of a wind tunnel balance, FIG.
1B is a plan view of FIG. 1A, and FIG. 1C is FIG.
1A is a vertical sectional view taken along the line BB of FIG. 1B, and FIG. 2 is equipped with the wind tunnel balance of the embodiment shown in FIG. It is a longitudinal cross-sectional view which shows a test piece and a part of support device.

As shown in these figures, the wind tunnel balance 30
Is in an opening 21 formed along the axis of the test piece 20,
The outer cylinder 2 into which the outer peripheral surface is fitted and which is integrated with the test piece 20, and the test piece 20 are supported at a predetermined position in the wind tunnel. The tapered portion 9 is fitted and is tightened with the nut 5 that is screwed to the tip of the sting 04, and the inner cylinder 1 integrated with the sting 04 and the slit are cut to separate the inner cylinder 1 and the outer cylinder 2. The measuring unit 3 is interposed between the two and is deformed by the aerodynamic force acting on the test piece 20, and the aerodynamic load applied to the test piece 20 is detected by the deformation amount.

The measuring unit 3 is arranged at two positions equidistant from the balance center 10 in the X-axis direction.
The rear measuring unit 32 is provided, and both measuring units 3 have both ends connected to the inner cylinder 1 and the outer cylinder 2, and four receiving units are arranged in the circumferential direction of the outer peripheral edge portions of the inner cylinder 1 and the outer cylinder 2. Sensing part 6 and sensing part 6
Is attached in the circumferential direction to the test piece 20, detects the circumferential deformation of the sensing portion 6, and applies the load (reaction force) in the X-axis direction, F, to the sample 20.
x, Y-axis direction load (lateral force), Fy, Z-axis direction load (lift force), Fz, and the balance center 10 around the X axis (rolling moment), Mx, around the Y axis (pitching) Moment), My, Z
The sensing unit element 8 detects the moment around the axis (yaw moment) and the 6-component force of Mz.

The thus configured wind tunnel balance 30 of the present embodiment ensures the strain output of the sensing section element 8 and
Since the main purpose is to increase the rigidity of the wind tunnel balance 30, the sensing unit 6 to which the sensing unit element 8 is attached is arranged as close to the outer peripheral edge side of the inner cylinder 1 and the outer cylinder 2 as possible. Thus, the diameter of the inner cylinder 1 is maximized. Further, the aerodynamic load applied from the outer cylinder 2 to the sample 20 entering the sensing section 6 is the load in the X-axis direction, and the other 5 component force, except that Fx is detected by the bending deformation of the sensing section 6, Fy, Fz, Mx, My, Mz are
All of them were detected by the tensile and compressive loads generated in the front and rear measuring units 31 and 32. As a result, the amount of deformation of the sensitive portion 6 can be reduced, and high rigidity can be achieved. Therefore, in the sensing unit element 8 attached to the sensing unit 6, Fx is for detecting the strain caused by the bending deformation of the sensing unit 6, and the other 5 component forces are provided in the front and rear measuring units 31, 32, respectively. Strain deformation caused by tensile and compression deformation is detected in the sensed portion 6 thus formed.

In this embodiment, the front and rear measuring units 31,
Although 32 is shown as being equidistantly separated from the balance center 10 and provided with two pieces, the present invention is not limited to such a form, and a different distance from the balance center 10 may be set depending on the measurement purpose. They may be separated from each other, and the number of measuring units 3 can be two or more.

Next, FIG. 3 is a view showing a second embodiment of the present invention. FIG. 3 (A) is a front view of a wind tunnel balance and FIG. 3 (B).
3A is a plan view, FIG. 3C is a sectional view taken along the line CC of FIG. 3A, and FIG. 3D is a longitudinal sectional view taken along the line D-D of FIG. 3B. Is. The wind tunnel balance of this form has a structure in which two measuring units 3 similar to those of the conventional wind tunnel balance shown in FIG. However, the cross-sectional shape of the inner cylinder 1'is circular like the first embodiment.

Therefore, the cross-shaped sensing portions 6 provided between the inner cylinder 1'and the outer cylinder 2 are provided at the positions equidistant from the balance center 10 in the front and rear rows, respectively. The load that has entered the cylinder 2 is transmitted to the cylinder 1 through the eight sensing units 6. As described above, by providing the measuring unit in which the sensing unit 6 is arranged in the front and rear, it becomes easy to design the strain output amount of the sensing unit element 8 provided in the sensing unit 6 with respect to the 6-component force load. Further, since the wind tunnel balance 30 of the present embodiment has a possibility of lowering the rigidity of the inner cylinder 1 ′ as compared with the wind tunnel balance 30 of the first embodiment,
A slit 7 for separating the outer cylinders is provided in the central portion of the sensitive portion 6 to prevent this.

[0023]

As described above, according to the wind tunnel balance of the present invention, due to the constitutions set forth in the claims, (1) around the Y and Z axes, which is difficult with the conventional wind tunnel balance. It is possible to relatively reduce the measurement capacity for the moment around the X-axis and the load for the X-axis direction or to increase the sensitivity without lowering the rigidity for the moment and the load in the Y- and Z-axis directions. The measurement accuracy of can be improved. Further, with respect to the moments about the Y and Z axes, it is possible to manufacture a relatively small scale even for those requiring a large moment load.

(2) The natural frequency of the wind tunnel balance can be increased, and high-accuracy measurement can be achieved in a high-temperature shock wind tunnel or the like with a very short measurement time. That is, as shown in FIG. 4, a high vibration output within the measurement time is possible for the vibration component of the balance output due to the impact force at the start of ventilation,
By simply averaging the vibration output, it becomes possible to calculate a steady average output, and it becomes possible to accurately measure a steady aerodynamic load applied to the specimen.

[Brief description of drawings]

FIG. 1 is a view showing a first embodiment of a wind tunnel balance of the present invention, FIG. 1 (A) is a front view of the wind tunnel balance, and FIG. 1 (B) is a plan view of FIG. 1 (A). 1 (C) is the arrow A- in FIG.
1A is a sectional view, and FIG. 1D is a vertical sectional view taken along the line BB in FIG.

FIG. 2 is a vertical cross-sectional view of a specimen equipped with the wind tunnel balance of the form shown in FIG. 1 and a supporting device;

FIG. 3 is a view showing a second embodiment of the present invention, and FIG.
(A) is a front view of the wind tunnel balance, and FIG. 3 (B) is FIG. 3 (A).
3C is a cross-sectional view taken along the line CC of FIG. 3B, and FIG. 3D is a vertical cross-sectional view taken along the line D-D of FIG. 3C.

FIG. 4 is a diagram showing the output of a sensing element in a wind tunnel test with a very short ventilation time;

5 is a diagram showing an example of a conventional wind tunnel balance, and FIG.
5A is a plan view and FIG. 5B is a view EE in FIG. 5A.
5C is a cross-sectional view taken along the line FF of FIG. 5A, and FIG. 5D is a cross-sectional view taken along the line GG of FIG. 5C.

[Explanation of symbols]

 1, 1 ', 01 Inner cylinder 2,02 Outer cylinder 3,03 Measuring part 31 Front measuring part 32 Rear measuring part 04 Sting 5 Nut 6,06 Sensing part 7 Slit 8,08 Sensing part element 9 Tapered part 10, 010 Balance center 011 (Sting's) hole 20 Specimen 21 (Specimen's) open hole 30,30 'Wind tunnel balance

Claims (1)

[Claims] 1. An outer cylinder fitted into an opening provided in a specimen to be subjected to a wind tunnel test and integrated with the specimen, and provided at a tip of a sting for supporting the specimen in the wind tunnel. An inner cylinder fitted into the opening and integrated with the sting,
Also, the sensing element, which is interposed between the outer cylinder and the inner cylinder and is deformed by the aerodynamic force acting on the sample to detect the aerodynamic load of the sample, has one row in the X-axis direction. A wind tunnel balance comprising a measurement unit provided, wherein a plurality of the measurement units are provided apart from the center of the balance in the front-back direction.