JPH07260621A - Apparatus for reducing interference of wind tunnel wall - Google Patents

Abstract

PURPOSE:To realize aerodynamic characteristics close to those of an aircraft flying in the atmosphere by suppressing the asymmetry of upper and lower air flows of a measuring model set in a wind tunnel when the attitude angle thereof is varied. CONSTITUTION:In order to vary the attitude angle of a measuring model 4 set in a wind tunnel, a plurality of pressure measuring holes 6 are made through opposing wind tunnel walls 1, 2 on the operating side and the pressure distribution on the wind tunnel wall surface is determined when an attitude angle is imparted to the measuring model 4. The model 4 is shifted to one wind tunnel wall face side until the pressure distribution is substantially equalized between both wind tunnel walls 1 and 2. This structure brings about a state where the model 4 is substantially set in the atmosphere and a data close to that of an aircraft flying in the atmosphere can be obtained from the model 4. Consequently, the aerodynamic characteristics of an actual aircraft can be estimated accurately based on the measurement data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention can improve the measurement accuracy by reducing the asymmetrical flow occurring in the angle changing direction of the measurement model and both sides caused by changing the attitude angle of the measurement model installed in the wind tunnel. The present invention relates to a wind tunnel wall interference amount reduction device.

[0002]

2. Description of the Related Art A wind tunnel test has been conventionally performed in which the aerodynamic characteristics of a measurement model in each posture angle are measured by changing the posture angle of the wind tunnel in various directions. There are various changes in the posture angle, such as when the angle of attack or yaw angle of the measurement model is changed, and as a method of changing the posture angle, as shown in FIG. The rear end of the sting 02 is moved up and down by the vertical movement device 03 to change the inclination of the sting 02 around the center of rotation provided slightly forward of the rear end. Furthermore, in this case, the measurement model 01 is always held at the center of the wind path of the wind tunnel.

On the other hand, the measurement model, which is not limited to the case of an aircraft, is usually asymmetric because the shape is different between the front and the rear, and the attitude angle of the measurement model is at the center of the wind passage. Despite the change, the airflow condition between the upper side of the measurement model and the wind tunnel wall (hereinafter referred to as the upper airflow condition)
The airflow condition between the lower side of the measurement model and the wind tunnel wall (hereinafter referred to as the lower airflow condition) is affected by the wind tunnel wall and is different.

Further, when measuring the aerodynamic characteristics of a measurement model in a transonic or supersonic flow, the angles of the shock wave and the disturbance wave generated from the measurement model change depending on the shape of the measurement model and the attitude angle changes. Due to abrupt fluctuations and interference with the wind tunnel wall, the upper airflow state and the lower airflow state become quite different, making it difficult to simulate the airflow state in the atmosphere (flying state).

Therefore, in a conventional wind tunnel test in which the wind tunnel wall is formed of a fixed wall and the attitude angle of the measurement model is changed, an asymmetric flow different from the atmosphere is generated by the wind tunnel wall, and this wall interference causes a disturbance of the actual machine. The aerodynamic characteristics could not be estimated accurately, which sometimes hindered the design of the aircraft.

Therefore, as shown in FIG. 5, the wind tunnel wall is constituted by the flexible wall 04, and the wind tunnel wall itself is moved by the flexible wall actuator 05 according to the posture angle of the measurement model, and the same as in the atmosphere. Although there is a conventional idea of creating an upper airflow state and a lower airflow state, the device becomes very complicated, and control for forming a flexible wall 04 having the same shape for the upper and lower airflow states is performed. Due to the difficulty and the enormous cost of constructing such a wind tunnel, there are no real cases in other countries, and it is currently in the research stage.

[0007]

DISCLOSURE OF THE INVENTION The present invention is a simple device, which can make the upper airflow state and the lower airflow state at the time of bending of the measurement model substantially the same by simple control without enormous cost. It is an object of the present invention to provide a wind tunnel wall interference reduction device that can obtain measurement data that is close to the aerodynamic characteristics of a real machine by placing a measurement model in a symmetrical flow state that is substantially the same as in the atmosphere.

[0008]

Therefore, the wind tunnel wall interference amount reducing device of the present invention has the following means. (1) A plurality of pressure measurement holes were arranged at symmetrical positions on both sides of the fixed wall of the facing wind tunnel on the side where the posture angle of the measurement model installed in the wind tunnel was changed. (2) A comparison calculator for comparing pressure distributions on both sides of the wind tunnel wall measured by the pressure measurement holes on both sides of the fixed wall facing each other is provided. (3) Measurement by changing the attitude angle to a position where the difference in pressure distribution on both surfaces of the fixed wall facing each other is within an allowable value due to the signal from the comparison calculator and substantially the same pressure distribution is formed on both surfaces of the fixed wall. A moving device for moving the model in parallel to one of the opposing fixed walls was provided.

[0009]

According to the wind tunnel wall interference amount reducing device of the present invention, the upper airflow state and the lower airflow state of the measurement model whose posture angle is changed can be made substantially the same by the above-mentioned means, and the measurement model is installed in substantially the atmosphere. The measurement data obtained from the measurement model can be approximated to that of the actual aircraft flying in the atmosphere, and the aerodynamic characteristics of the actual aircraft can be accurately estimated from the measurement data.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the wind tunnel wall interference amount reducing device of the present invention will be described below with reference to the drawings. 1 is a side view showing an embodiment of the wind tunnel wall interference amount reducing device of the present invention, FIG. 2 is a plan view, FIG. 3 is a front view, and FIG. 4 is a control block diagram.

As shown in the figure, in the wind tunnel formed by the wind tunnel wall consisting of the upper fixed wall 1, the lower fixed wall 2 and the left and right fixed walls 3, the measurement section provided with the measurement window 15 measures The model 4 responds to the test request by using the bending device 5 to adjust the model posture angle θ.
It is arranged so that it can be set to.

Of the fixed walls 1 to 3, the fixed wall on the side where the measurement model 4 is operated due to the change in posture of the measurement model 4,
In the present embodiment, the measurement model 4 is operated so that the measurement model 4 is tilted upward and downward, and the posture is changed. Therefore, the upper fixed wall 1 and the lower fixed wall 2 are controlled by There are at least 20 pressure measurement holes 6 used in the above, arranged as shown in FIG. 2, and symmetrically formed in the upper fixed wall 1 and the lower fixed wall 2.

The pressure (static pressure) on the inner surfaces of the upper fixed wall 1 and the lower fixed wall 2 is measured from the pressure measuring hole 6 by a measuring device (not shown). The pressure distribution on the wall surface can be obtained. It should be noted that, as shown in FIG. 1, the array position of the pressure measurement holes 6 needs to be a position that is not affected by the shock wave 7 and the disturbance wave generated from the surface of the measurement model 4 during supersonic measurement.

As described above, the set measurement model 4
Is a measurement model 4 that measures the aerodynamic force applied to the measurement model 4.
By moving up and down the vertical movement device 9 having the rear end of the sting 8 connected to the rear end of the balance, which is pivotally attached, the sting 8 around the rotation center provided in front of the pivot point is The posture angle θ is rotated and tilted, and the posture angle θ is changed and set from the non-variable angle state shown by the chain line in FIG. 1 to the variable angle state shown by the solid line. By setting the posture angle θ of the measurement model 4, asymmetrical up and down air flows are generated above and below the measurement model 4 as indicated by 10 in FIG. This is an asymmetrical flow generated when the airflow is constrained by the upper and lower fixed walls 1 and 2, and is different from the state of the airflow flying in the atmosphere.
Therefore, even if the aerodynamic load applied to the measurement model 4 in this state is measured by the balance, the measurement data will be different from that of the actual aircraft that is flying in the atmosphere.

Therefore, in this embodiment, the asymmetric flow is made to be a symmetric flow by the following procedure.

First, the pressure associated with the asymmetrical flow is measured by the pressure measuring hole 6, and the pressure distribution pattern on the upper fixed wall 1 surface and the lower fixed wall 2 surface is hit by using this pressure measured value. Normalize.

Next, this result is arithmetically processed to find the difference between the pressure distribution on the upper fixed wall 1 surface and the pressure distribution on the lower fixed wall 2 surface, and the model vertical moving device 9 is set so that the difference falls within the allowable value. By controlling and performing parallel movement in the model up-and-down movement direction 11 while maintaining the posture angle of the measurement model 4, by repeating this ascending / descending operation depending on the polarity of the difference, the difference finally becomes a predetermined allowance. Fits in range. In the design of this control system, feedback is applied from the pressure detection to control the up / down operation of the measurement model so that the pressure distribution on the upper fixed wall 1 surface and the lower fixed wall 2 surface are within the allowable range. Although it is important to carry out the operation for storing in a short time, in this embodiment, pressure detection can be performed in a short time of 2 to 3 msec, and the model position can be controlled within a range of 10 msec. Everything can be operated and controlled by a computer so that the time can be 10 to 20 msec.

With respect to the wall interference amount, the vertical movement amount of the measurement model is used as a parameter (at this time, the allowable value of the difference is variable by the input of the computer), and the aerodynamic load with respect to the movement amount is obtained and calculated. In this case, it is naturally possible that there is a limit that the wind tunnel is a fixed wall, so it is impossible to obtain data in the complete atmosphere, but it can be obtained by extrapolation by a computer from the relationship between the movement amount and aerodynamic load.

Next, the control of the wind tunnel wall interference amount reducing device of this embodiment will be described with reference to FIG. In order to set the attitude angle θ of the measurement model 4, a model attitude angle command is output from the computer, and the measurement model 4 is set to the required angle θ continuously or stepwise by the model attitude angle changing device. The attitude angle θ is detected by a potentiometer, which is an attitude angle detector, or an encoder. When the bending device 5 by the sting 8 wearing the measurement model 4 changes the attitude angle based on the signal together with the measurement model 4 by the signal from the model attitude angle changing device, the uniform flow state of the wind tunnel is measured. The state is different between the top and bottom of the model 4. This is the so-called air flow disturbance. This air flow disturbance is detected by the pressure measuring holes provided on the upper fixed wall 1 and the lower fixed wall 2, and the pressure measuring holes 6 are respectively detected.
Is measured as the pressure at.

This measured pressure signal is transmitted to a computer and is normalized into a pressure distribution pattern. A pressure difference between the pressure distribution on the upper fixed wall 1 surface and the pressure distribution on the lower fixed wall 2 surface is calculated by a comparison calculator, and the pressure distribution difference allowable value set in advance by input or the like is used. When compared and within the allowable value, especially measurement model 4
However, if it is not within the allowable value, a vertical movement command is issued to the vertical moving device 9 and the vertical moving device 9 is controlled until the pressure difference falls within the allowable value to bring the optimum difference. . The vertical movement amount is detected by a movement amount detector (normally a linear potentiometer), and it is continuously monitored that it is within the movement limit. With this series of controls, the non-uniform flow of the flow above and below the measurement model 4 is mitigated, and highly accurate aerodynamic data can be acquired.

As described above, in the present embodiment, when a large number of pressure measurement holes 6 are provided on both the fixed walls 1 and 2 on the side where the measurement model 4 of the wind tunnel is bent and the posture angle of the measurement model 4 is changed. , In order to bring the upper and lower sides of the measurement model 4 as close as possible to the state of airflow flying in the atmosphere, the pressure distribution on both fixed walls 1 and 2 is detected, and the position of the measurement model 4 is adjusted so that the upper and lower flows are balanced. The angle is changed while being held, and the aerodynamic load applied to the measurement model 4 is measured at the balanced position. As a result, it is possible to improve the inaccurate aerodynamic characteristic estimated value calculated using the measured value including the error in the asymmetrical flow.

Although the measurement model 4 is operated in the vertical direction of the wind tunnel in the above embodiment, the present invention is not limited to this. However, the pressure measurement holes 6 are installed on both fixed walls on the side where the measurement model 4 is operated, as in the embodiment.

[0023]

According to the wind tunnel wall interference amount reducing device of the present invention, the asymmetrical flow generated by the change of the attitude angle of the measurement model, which occurs due to the change of the attitude angle of the measurement model, is a symmetrical flow due to the configuration described in the claims. The amount of wall interference can be reduced by approaching to. Further, the device is not complicated and the control can be easily performed. Further, the repair of the wind tunnel can be achieved by installing a slight pressure measuring hole and modifying a part of the control circuit of the up-and-down moving device, so that an enormous cost is not generated. (2) In addition, the wall interference amount is calculated from the relationship between the vertical movement amount of the measurement model and the aerodynamic load measurement value, and the aerodynamic load measured in the wind tunnel test is corrected to obtain the aerodynamic load during atmospheric flight. It is possible to improve the estimation accuracy.

Therefore, the wind tunnel wall interference amount reducing device of the present invention can contribute to an indispensable safety design in designing an aircraft.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a wind tunnel wall interference amount reducing device of the present invention.

FIG. 2 is a plan view of the embodiment shown in FIG.

FIG. 3 is a front view of the embodiment shown in FIG.

FIG. 4 is a control system diagram of the embodiment shown in FIG.

FIG. 5 is a side view showing an example of a conventional flexible wall.

[Explanation of symbols]

 1 Upper fixed wall 2 Lower fixed wall 3 Left and right fixed wall 4 Measurement model 5 Bending device 6 Pressure measuring hole 7 Shock wave 8 Sting 9 Vertical moving device 10 Airflow 15 Measurement window

Claims (1)

[Claims] 1. A plurality of pressure measurement holes symmetrically arranged on both sides of a fixed wall of a measurement model in a bending direction installed in a wind tunnel, and pressure distributions on both sides of the fixed wall measured by the pressure measurement holes. From a moving device that translates the measurement model in one direction of the fixed wall to a position where the pressure distribution on both surfaces of the fixed wall is within an allowable value, based on a signal from the comparison operator that compares A wind tunnel wall interference reduction device.