JPH04305139A - Balance apparatus for wind tunnel test - Google Patents

Abstract

PURPOSE:To enable measurement of an air component working on a model at a high accuracy and in a wide range to a high elevation in a wind tunnel test. CONSTITUTION:This apparatus is provided with a model 1 for the wind tunnel test, a sting 5 which extends into a body of the model to support the model at the tip thereof while having a scale and an air bearing 3 provided between the body of the model 1 and the sting. The use of the air bearing 3 with a small friction force enhances a measuring accuracy to prevent a contact between the model 1 and the sting when an air force works thereby enabling the expansion of a testing area at a high angle of incidence.

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 aerodynamic force applied to wind tunnel tests.

0002

2. Description of the Related Art Conventionally, in wind tunnel tests of elongated bodies such as flying objects and aircraft, aerodynamic forces acting on a model 11 have been measured using the configuration shown in FIGS. 8 and 9.

That is, in the case shown in FIG. 8, the sting 13 extends forward inside the body of the model 11 and supports the model 11 at its front end, and the small capacity balance 12 is attached to the sting 12 near the aerodynamic center of the model 11. It is placed. In the case shown in FIG. 9, the length of the sting 13 extending inside the body of the model 11 is shortened, and the large-capacity balance 14 is disposed at the rear of the body of the model 11.

In these cases, the bending moment acting on the support system consisting of the balance and the sting is as shown in FIG. 11, and the deflection distribution of the sting is as shown in FIG.
It becomes as shown in .

In both the cases shown in FIGS. 8 and 9, the test area is until the inner diameter of the fuselage and the outer diameter of the sting come into contact (see FIG. 10), but in the case shown in FIG. 8, the rigidity of the support system is It is small and the sting is long inside the model body, making it easy to bend as a whole.

[0006]

[Problem to be solved by the invention] In a wind tunnel test of a flying object with an elongated fuselage and small wings, the fuselage axis (X-axis)
In order to accurately detect the surrounding rolling moment (Mx), the conventional device described above has the following drawbacks.

(1) The point of action of the large aerodynamic force generated on the model is around 50% of the total length of the fuselage. Therefore, in the device shown in Fig. 8, which measures the aerodynamic force by placing a balance with a small capacity rolling moment detection element at this position, the support system (
The entire body (the balance and the sting) is deflected, and the inner diameter of the rear end of the model body and the outer shape of the sting come into contact, making measurement impossible (Figure 10).
reference).

(2) In the device shown in FIG. 9, in which the position of the balance is moved from the center of the model body to the rear in order to prevent contact and conduct tests up to a slightly larger angle of attack, the support system is made more rigid. This reduces deflection and allows testing up to a large angle of attack. However, by moving the balance backwards, a large pitching moment is applied to the balance, which damages the small-capacity rolling moment detection element, and in order to prevent this, a large-capacity rolling moment detection element is required. Additionally, since a small rolling moment is measured using a large-capacity balance, the accuracy of the wind tunnel test deteriorates.

[0009] The present invention aims to provide a balance device for wind tunnel testing that can overcome the drawbacks of the conventional ones.

0010

[Means for Solving the Problems] A wind tunnel test balance device of the present invention includes a wind tunnel test model, a sting that extends into the body of the model and supports the model at its tip and is provided with a balance, and the body and the sting. It has an air bearing installed between the stings.

[0011]

[Operation] In the present invention, since an air bearing with a small frictional force is provided between the model body and the sting, the accuracy of measuring the aerodynamic force and moment caused by the balance is improved.

Furthermore, when an aerodynamic force acts on the model, the sting that supports the model bends, causing a change in the gap between the body of the model and the sting. In the area where the gap between the fuselage and Sting becomes smaller, the air pressure in the air bearing increases, and in the area on the opposite side where the gap becomes larger, the air pressure in the air bearing decreases. A force is generated to return the gap to its original state, and the gap between the two is maintained constant. This prevents the model from colliding with the sting and expands the test area.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be explained with reference to FIGS. 1 to 7.

In FIG. 1, reference numeral 1 denotes a model of a flying object or the like, and a vertical hole 1A is provided in the body of the flying object, which extends from the rear beyond its axial center to the front. Reference numeral 5 denotes a sting whose rear end is fixed to the sting pot 20 of the wind tunnel and extends forward almost horizontally.The sting 5 is inserted into the vertical hole 1A and supports the model 1 at its front end. Reference numeral 2 denotes a rolling moment (Mx) detection element section serving as a balance attached to the vicinity of the axial center of the body of the model 1 of the Sting 5, and at the rear of the vertical hole 1A, the inner periphery of the vertical hole 1A and the outer periphery of the Sting 5 are connected. An air bearing 3 is provided over the entire circumference. Sting 5 air bearing 3
At the rear position, there are four component forces (lateral force (FY), vertical force (FZ)) as a balance with a strain gauge for bending strain detection.
), pitching moment (MY), yawing moment (MZ)) detection element section 4 is attached. Reference numeral 6 denotes an air supply hole that passes through the center of the sting 3 and supplies high-pressure air to the air bearing 3.

In the air bearing 3, FIGS. 2 and 3
As shown in FIG.
A small gap 9 of 30 microns is provided, and this gap 9 and the air supply hole 6 in the sting 5 are communicated by eight small-diameter air supply holes 7 provided at eight equal positions on the circumference. Further, an exhaust hole 8 is provided in the body of the model and extends to the rear end, and the exhaust hole 8 communicates with a gap 9.

As shown in FIGS. 5 and 6, the portion of the sting 5 where the rolling moment detecting element portion 2 is provided has a radial width of 0.5 mm toward the center of the sting 5.
A plurality of slits 16 of 5 to 0.6 mm are provided, and the sting 5 is provided with rectangular portions 17, 17 provided at symmetrical positions on both sides of the center of the sting in the horizontal direction. Rolling moment detection elements 15a, 15b, 15c, 15d are installed on the upper and lower surfaces of
are attached, and these elements 15a, 15b, 1
5c and 15d are arranged in a bridge circuit for detecting rolling moment, as shown in FIG.

In this embodiment, high pressure air is supplied from the rear of the sting 5 to the air supply hole 6 as shown by the arrow in FIG.
, air is supplied to the gap 9 through the air supply holes 7 located at eight equal intervals on the circumference, and the air leaking from the gap 9 passes through the exhaust hole 8 and is discharged from the rear end of the body of the model 1. In this way, by using the air bearing 3 in which the model 1 and the sting 5 do not come into contact with each other, the frictional force is small, and the detection element parts 2, 4
The aerodynamic force can be measured with high accuracy.

When no aerodynamic force acts on the model 1, there is no shared load on the air bearing portion 3, and the gap 9 is kept uniform over the entire circumference. As shown in FIG. 4, when an aerodynamic force, for example a vertical force FZ, acts on the model 1, an imbalance occurs in the gap 9. On the side where the gap 9 is narrower, the air pressure in the gap 9 increases, and conversely, on the side where the gap 9 is wider, the air pressure in the gap 9 decreases, trying to return the gap 9 to its original state. A force F2 is generated. As a result, the gap 9 is kept at a constant size, the frictional force between the model 1 and the sting 5 is kept small, and the aerodynamic force of the detection element parts 2 and 4 can be measured accurately. Also, the body of model 1 and Sting 5
The test area can be expanded by avoiding collisions. Moreover, the air bearing 3 is composed of a small gap 9 and an air supply hole 7 and an exhaust hole 8 for sucking and discharging high-pressure air there, and can be easily installed in a narrow space between the body of the model 1 and the sting 5. .

The aerodynamic force FZ acting on the model 1 is, as shown in FIG.
2, and the bending moment distribution created by this is shown in the lower part of Fig. 4. In addition, in FIG. 4, the bending moment distribution in the case where no air bearing is provided is shown by a chain line. The optimal design can be achieved by selecting the shape and supply pressure of the air bearing according to the aerodynamic force acting on model 1, and by selecting the position of the air bearing part depending on the point of aerodynamic force acting on model 1. It will be done.

[0020] Furthermore, the rolling moment detection section 2
In order to suppress the deflection between the sting 5 and the model 1 in the air bearing 3, it is required to have a small capacity but high rigidity with respect to other component forces. In this embodiment, as shown in FIGS. 5 and 6, a plurality of radial slits 16
is provided on the sting 5, and the detection elements 15a to 15d are attached to the rectangular portions 17, 17 of this portion, so that the rolling moment can be detected with high accuracy and the rigidity of the sting 5 against the rolling moment is maintained at a high level. be able to. Further, the rolling moment detection unit 2 detects a model 1 on which an aerodynamic force acts on the model 1.
As shown in FIG. 4, the bending moment acting on this part is almost zero, and the detection elements 15a to 15d are not affected by this, and the detection Elements 15a-15
d is prevented from being damaged, and the accuracy of rolling moment detection can be increased.

Furthermore, as shown in FIG. 4, the moment distribution behind the air bearing 3 is the same as when there is no air bearing, so a strain gauge for detecting bending strain is attached here. By providing the force detection element section 4, the four component forces can be measured with high accuracy.

[0022]

According to the present invention, since an air bearing having a small frictional force is provided between the sting that supports the model and the model body, it is possible to measure the aerodynamic force etc. with a balance with high accuracy. In addition, even when aerodynamic forces act on the model, the distance between the model body and the sting in the air bearing is maintained constant, avoiding collision between the model and the sting, and expanding the test area to a large angle of attack range. can do.

[Brief explanation of drawings]

FIG. 1 is an overall view of an embodiment of the present invention.

FIG. 2 is a detailed view of the air bearing portion of the same embodiment.

FIG. 3 is a sectional view taken along line AA in FIG. 2;

FIG. 4 is an explanatory diagram showing the aerodynamic force acting on the model and the bending moment distribution acting on the sting in the same example.

FIG. 5 is an elevational view of the rolling moment detection section of the same embodiment.

FIG. 6 is a sectional view taken along line BB in FIG. 5;

FIG. 7 is a wiring diagram of the strain gauge of the rolling moment detection section of the same embodiment.

FIG. 8 is an overall view of an example of a conventional balance device for wind tunnel testing.

FIG. 9 is an overall view of another example of a conventional wind tunnel test balance device.

FIG. 10 is a deflection distribution diagram of the conventional wind tunnel test balance device.

FIG. 11 is a bending moment distribution diagram of the conventional wind tunnel test balance device.

[Explanation of symbols]

1 Wind tunnel test model 1A Model vertical hole 2 Rolling moment detection element section 3
Air bearing 4 4-component force detection element section 5 Sting 6 Air supply hole 7 Air supply hole 8 Exhaust hole 9 Gap 15a to 15d Strain gauge 16 Slit 17 Rectangular portion

Claims (1)

[Claims] 1. A model for wind tunnel testing, comprising: a sting that extends into the body of the model and supports the model at its tip and is provided with a balance; and an air bearing provided between the body of the model and the sting. A wind tunnel test balance device characterized by: