JPH04175628A - Variable mach number wind tunnel nozzle - Google Patents

Abstract

PURPOSE:To greatly enhance the test capability by inserting a center body into a nozzle section so as to change the distribution of flow passage area in order to obtain a given Mach number. CONSTITUTION:Since a nozzle is axially symmetric (that is, cylindrical) a center body 5 to be inserted thereinto has an axially symmetric cross-sectional area so as to support the center body in a rectifying cylinder 9. A center body sup port section 8 is provided therein with a drive device 6 and a drive mechanism 7 with which the center body is moved longitudinally, and a hydraulic actuator or a motor is used as the drive device 6, and a telescopic system composed of concentric cylinders, a gear system or the like is used as the drive mechanism 7.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an aerodynamic testing device, a variable Matsuha number wind tunnel nozzle.

[Conventional technology]

In a supersonic wind tunnel, supersonic airflow is generally created by adiabatic expansion of airflow. That is, as shown in the vertical cross-sectional view of FIG.
As shown in FIG. The airflow Matsuha number of the measuring section is uniquely determined by the ratio of the flow path cross-sectional areas. This is the same in wind tunnels with a circular cross section as well as wind tunnels with a rectangular cross section, and the flow path cross-sectional area distribution with respect to the airflow direction is essentially the only parameter.

In this way, the air flow rate at the measuring section is determined by the ratio of the cross-sectional area of the measuring section to the throat cross-sectional area, so in an actual wind tunnel, the wind tunnel wall can be deformed as shown in Figure 5. The structure is made of a thin flexible plate 14 and held by an actuator 12, and by changing the length of the actuator 12, the cross-sectional area distribution of the wind tunnel flow path is changed. The number of actuators 12 is selected so that the flexible plate 14 is deformed with a stress that does not cause permanent deformation, and the actuators may be hydraulic or electric.

The example in Figure 5 changes the Matsuha number without changing the components, but the Matsuha number can be changed by completely replacing the wind tunnel section from the throat to the measurement section with another section and changing the flow channel cross-sectional area distribution. There is also a method wind tunnel.

[Problem to be solved by the invention]

The problems with the conventional wind tunnel variable Matsuha number structure described above can be summarized as follows.

(11 The nozzle wall must be made of a thin plate and have a structure that allows for elastic deformation.

(2) The structure becomes complicated due to the arrangement of many actuators, which may cause failure.

(3) Since the wind tunnel wall must be moved symmetrically, high precision is required to control the amount of movement of the actuator.

(4) It is not easy to change the Matsuha number during ventilation, that is, to shift the Matsuha number.

Furthermore, even if possible, it is practically impossible to sweep the Matsuha number over a wide range in a short period of time, for example, to change the Matsuha number from 2.0 to 3.0 in 10 seconds.

The present invention has been devised in view of these circumstances, and provides a variable Matsuha number wind tunnel nozzle that has a simple structure, low cost, and high precision, and that can widely change the Matsuha number and greatly expand testing capabilities. The purpose is to serve.

[Failure to solve the problem]

To this end, the present invention aims to insert a center body into the nozzle part that sets the air flow Matsuh number in a wind tunnel where the aerodynamic characteristics of aircraft models, etc. It is characterized by what it did.

[Effect]

According to such a configuration, the cross section of the wave path at the throat has an annular shape in an axially symmetrical nozzle, and has a two-channel shape in a two-dimensional nozzle.

In any cross-sectional shape, the Matsuha number of the measuring section is determined by the ratio of the flow path cross-sectional areas, and a predetermined supersonic airflow can be obtained.

If the center body is held in the upstream rectifying tube section, the flow velocity is low here, so almost no disturbance to the measurement section will occur.

Furthermore, by making the center body movable in the airflow direction, if the shape of the wind tunnel wall and the shape of the center body are appropriately designed, a predetermined Matsuha number can be obtained depending on the airflow direction setting position of the center body.

Furthermore, if the center body moves in the direction of the airflow during ventilation, a Matsuha number sweep can be easily performed.

〔Example〕

Embodiments of the present invention will be explained with reference to the drawings. FIG. 1 is a longitudinal sectional view showing the first embodiment, FIG. 2 is a perspective view and longitudinal sectional view showing the second embodiment, and FIG. 3 is a longitudinal sectional view showing the second embodiment. FIG. 6 is a vertical cross-sectional view and a partial cross-sectional view showing a seal portion of the wind tunnel wall shown in the figure for the nozzle.

In the above figure, the same reference numerals as in Figs. 4 and 5 indicate the same members as in the same figure. First, the first embodiment shown in Fig. 1 uses an axially symmetrical nozzle; (cylindrical), the center body 5 to be inserted also has an axially symmetric cross-sectional shape, and the center body is supported within the rectifying tube 9.

The center body support section 8 is provided with a drive device [6] and a drive mechanism 7 that move the center body in the front and back direction, the drive device 6 uses a hydraulic actuator or an electric motor, and the drive mechanism 7 has a concentric cylinder. Telescopic method, gear method, etc. are adopted.

Next, in the second embodiment shown in FIGS. 2 to 4, a two-dimensional nozzle is used, and the two-dimensional nozzle has opposing surfaces.

In this example, the center body 5 to be inserted also has a two-dimensional shape and is held by the wind tunnel wall having a rectangular cross section, so that it is not necessary to hold it by the rectifier tube 9.

On the outside of the wind tunnel wall, as shown in FIG. 3, there is a support part 8 for the center body. A drive device 6 and a drive mechanism 7 are provided that enable the center body to move in the front-rear (airflow) direction. support part,
The drive device and drive mechanism may be the same as those in the first embodiment.

In this example, in order to support the center body through the wind tunnel wall, it is necessary to make an opening 15 in the wind tunnel wall.
Airflow sealing problems therefore arise. On the contrary,
As shown in the figure, a liquid 11 is placed in a bag 10 and this is inserted into an opening 15. This bag then fills the gap between the opening created by the end face of the wind tunnel wall and the center body, blocking the flow of air inside and outside the wind tunnel and creating a seal.

If the opening is small, it may not be necessary to seal it. Another option is to cover and seal the entire area with a rubber-like material.

The shape of the center body 5 is selected in accordance with the shape of the wind tunnel wall and designed based on aerodynamic theory. Generally, if the center body 5 is designed so that the change in the cross-sectional area distribution of the flow path is smooth, good airflow characteristics can be obtained at the measurement section.

The shape of the wind tunnel wall can be fixed, and the number of mats can be determined by setting the center body position, or the wind tunnel wall can have a variable shape using flexible plates as before, and the required flow passage cross-sectional area can be determined by setting the center body position. Distribution may also be realized.

According to such a wind tunnel nozzle, the following effects can be achieved.

(1) Since there is no need to change the shape of the nozzle wall, there is no need to manufacture it with a flexible plate, reducing manufacturing costs.

(2) There is no need for an actuator to set the nozzle wall shape, which simplifies the structure and reduces failures.

(3) Since there is no need for symmetry when moving around the wind tunnel wall, maintaining accuracy becomes a priority.

+41 i[11 Since it becomes possible to easily change the Matsuha number during the wind, the testing capacity of the equipment is greatly expanded,
Wind tunnel tests can now be conducted more efficiently.

〔Effect of the invention〕

In short, according to the present invention, in a wind tunnel for testing the aerodynamic characteristics of an aircraft model, etc., a center body is inserted into the nozzle part that sets the airflow Matsusha number to change the flow passage cross-sectional area distribution, and a predetermined Matsusha number can be obtained. This makes the structure simple.

Because you can obtain several wind tunnel nozzles for variable pine, which can greatly change the number of pine needles and greatly expand the testing capacity, with low cost and high precision.
The invention is of great benefit to the industry.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of the first embodiment of the present invention, Fig. 2 is a perspective view and longitudinal sectional view showing the second embodiment, and Fig. 3 is a seal for the nozzle on the wind tunnel wall of Fig. 2. FIG. FIG. 4 and FIG. 5 are longitudinal sectional views showing a wind tunnel for a known variable pine, respectively. l...Wind tunnel wall, 2...Supersonic airflow, 3...Measurement section, 4...Throat, 5...Center body, 6...
- Drive device, 7... Drive I! Horizontal, 8...Support part, 9
... rectifier cylinder, 10 ... bag, 11 ... liquid, 12.
...Hydraulic actuator-113...Pivot, 14
...Flexible plate, 15...Opening, 16
...Supersonic airflow, agent and patent attorney Masaru Tsuka Figure 2

Claims (1)

[Claims] In a wind tunnel used to test the aerodynamic characteristics of aircraft models, etc., a center body is inserted into the nozzle part that sets the airflow Mach number to change the cross-sectional area distribution of the flow path, so that a predetermined Mach number can be obtained. variable Mach number wind tunnel nozzle.