JPH0518853A - Apparatus for automatically controlling wind tunnel boundary layer - Google Patents

Abstract

PURPOSE:To automatically form the necessary thickness of a boundary layer within a short time by measuring the thickness of the boundary layer by a comb-shaped pitot pipe and automatically adjusting the thickness of a control mechanism until bringing the same to required thickness. CONSTITUTION:A comb-shaped pitot pipe 7 is arranged in the vicinity of an object 8 to be tested and the thickness of the boundary layer of the wall surface of a wind tunnel 1 is measured by a pressure converter 20. The thickness of the boundary layer is calculated from a pressure value on the basis of the measured value in an operation part to be subjected to the comparative operation with the required set value of a boundary layer control mechanism 21. If there is difference between the thickness value and the required set value, a variable angle plate 9 is revolved by the drive part 10 of the mechanism 21. At this time, a change in the thickness of the boundary layer is detected by a boundary layer thickness detecting part 11 and fed back in a circuit to stabilize a control circuit. As mentioned above, by controlling the height of the variable angle plate 9 within a short time, the boundary layer can be freely controlled to necessary thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wind tunnel boundary layer automatic adjusting device.

[0002]

2. Description of the Related Art In a wind tunnel test, Reynolds numbers and Mach numbers are used to establish the similarity between a model and a real machine. However, by controlling the boundary layer by utilizing the relationship that the thickness of the boundary layer changes depending on the Reynolds number, it is possible to obtain measurement accuracy close to that of an actual machine. Therefore, conventionally, as shown in the perspective view of FIG. 5, when the fixing metal fitting 3 is attached and the constant air flow 2 is ventilated, the boundary layer in the vicinity of the sample 4 is adjusted to a required thickness.

[0003]

However, such means have the following problems. (1) Prepare a plurality of fixtures with different thicknesses,
The thickness of the boundary layer must be adjusted by trial and error each time the size of the specimen changes, and the thickness of the boundary layer cannot be set arbitrarily. (2) In order to obtain the optimum correlation between the thickness of the boundary layer and the height of the fixing bracket, it is necessary to predict the boundary layer thickness in advance and manufacture a large number of fixing brackets accordingly. (3) In order to find the optimum thickness of the boundary layer, there are many trial tests and it is inefficient because the fixing metal cannot be selected easily.

The present invention has been proposed in view of the above circumstances, and measures the boundary layer thickness with a comb-type Pitot tube for measuring the boundary layer, and automatically measures the thickness until the desired thickness is reached. It is an object of the present invention to provide an automatic adjusting device for a boundary layer of a wind tunnel capable of adjusting a boundary layer thickness in front of a comb-shaped Pitot tube.

[0005]

To this end, the present invention measures the boundary layer thickness in a wind tunnel using a boundary layer measuring comb-type Pitot tube, and automatically forwards the comb-shaped Pitot tube to the desired thickness. It is characterized in that the thickness of the boundary layer adjusting mechanism of is adjusted.

[0006]

According to such a configuration, the following actions are exhibited. (1) The comb-shaped Pitot tube for boundary layer measurement protrudes from the flow path surface,
The dozen or so pitot tubes are arranged vertically, the pressures at the installation parts are measured, and the effective boundary layer thickness is calculated. (2) The calculated boundary layer thickness is fed back to the variable angle changing mechanism of the adjusting mechanism to perform the angle changing drive. (3) The variable angle type gonio plate allows the air flow to be angulated up to a right angle for fine adjustment, and a change in the angle of the gonio plate causes a change in the boundary layer thickness.

[0007]

Embodiments of the present invention will now be described with reference to the drawings.
1 is a perspective view showing the first embodiment, FIG. 2 is a control system diagram in FIG. 1, FIG. 3 is a perspective view showing the second embodiment of the present invention, and FIG. 4 shows a third embodiment of the present invention. It is a perspective view.

First, in the first embodiment shown in FIGS. 1 and 2, the same reference numerals as those in FIG. 5 denote the same members as those in the same drawing, and the comb-shaped Pitot tube 7 is installed in the vicinity of the test piece 8 to wind the tunnel. The boundary layer thickness 5 of the wall surface with the air flow is measured by the pressure converter 20. This measured value is taken into the computer 12, the calculation unit 22 calculates the boundary layer thickness from the pressure value, and the calculated value is compared with the initial setting value 13 of the boundary layer adjusting mechanism 21. The input value of the servo amplifier 15 changes and the displacement corresponding to the change is activated by the adjusting mechanism 21.
Here, the boundary layer adjusting mechanism 21 rotates the bending plate 9 by the driving unit 10, detects the change in the thickness of the boundary layer due to this, by the boundary layer thickness detecting unit 11, and feeds this back in the circuit. Stabilizes the control circuit. The present invention is capable of adjusting the thickness of the wall boundary layer in the vicinity of the specimen to an arbitrary thickness, and is characterized in that the signal from the pitot tube 7 is taken out and the adjusting mechanism is controlled in accordance with the signal. The height of can be controlled within a short time, and the required boundary layer thickness can be freely controlled.

Next, in the second embodiment shown in FIG. 3, the gonio plate is a gonio plate 23 in which a large number of through holes are formed vertically and horizontally to change the mixing of the air flow passing through the air holes and the air flow not passing therethrough. Generated behind the square plate. The degree of turbulence of the air flow around the rear sample 8 can be set to a required value by the degree of mixing of the air flow. Further, by sharpening the rear end of the bending plate 23, the boundary layer thickness can be adjusted with high accuracy.

Further, in the third embodiment shown in FIG. 4, the angle-changing plate 24 has its rear end rounded into an arc shape to change the degree of disturbance, that is, shock wave and expansion wave when the velocity of the air flow is high. The strength of the disturbance can weaken the disturbance by affecting the quality of the air flow characteristics around the specimen.

[0011]

According to such a structure, the following effects can be obtained. (1) Generate the required boundary layer thickness in a short time. (2) It becomes possible to freely control the thickness of the boundary layer at any position on the wall. (3) The characteristics of the wake can be changed by changing the length and shape of the gonio plate, which is applicable to the test using turbulence. (4) By installing the adjusting mechanism behind the test piece, it is possible to change the velocity of the uniform flow. (5) Efficiency can be improved by automation. (6) The degree of turbulence of the air flow can be adjusted.

In short, according to the present invention, the boundary layer thickness is measured by the boundary layer measuring comb-type Pitot tube in the wind tunnel, and the boundary layer adjusting mechanism in front of the comb-type Pitot tube is automatically measured until the desired thickness is reached. By adjusting the thickness of the boundary layer, the boundary layer thickness is measured with the comb-shaped Pitot tube for boundary layer measurement, and the boundary layer thickness in front of the comb-shaped Pitot tube is automatically measured until the desired thickness is reached. The present invention is of great industrial benefit because it provides an adjustable wind tunnel boundary layer automatic adjustment device.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a system diagram related to control in FIG.

FIG. 3 is a perspective view showing a second embodiment of the present invention.

FIG. 4 is a perspective view showing a third embodiment of the present invention.

FIG. 5 is a perspective view showing a known wind tunnel boundary layer adjusting device.

[Explanation of symbols]

 1 Wind Tunnel 2 Wind Tunnel Air Flow 5 Boundary Layer Thickness 6 Boundary Layer Adjustment Mechanism 7 Comb Pitot Tube 8 Specimen 9 Bending Plate 10 Drive Unit 11 Boundary Layer Thickness Detection Unit 12 Computer 13 Initial Setting Value 14 Manual Dial 15 Servo Amplifier 16 Drive Unit 17 Boundary Layer Adjusting Mechanism 18 Comb Pitot Tube 19 Boundary Layer Thickness Detector 20 Pressure Transducer 21 Boundary Layer Adjusting Mechanism 22 Computing Unit

Claims (1)

Claims: 1. A boundary layer thickness is measured by a comb-type Pitot tube for boundary layer measurement in a wind tunnel, and the boundary layer is automatically adjusted in front of the comb-shaped Pitot tube until a desired thickness is obtained. An automatic wind tunnel boundary layer adjusting device characterized by adjusting the thickness of the mechanism.