JPH05248985A - Wind tunnel - Google Patents

Abstract

PURPOSE:To easily and properly set the section area of an air flow path in accordance with any arbitrary Mach number by varying the section area without changing the shape of the flow path wall. CONSTITUTION:A wind tunnel is formed which is to control a uniform flow velocity by varying the section area of an air flow path for uniform streaming, wherein an air jet blow-in hole 4 is furnished upstream of a constant section area flow path wall 3 while an air flow suction port 5 is furnished downstream, and the section area of the air flow path is varied aerodynamically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wind tunnel suitable for a supersonic wind tunnel.

[0002]

2. Description of the Related Art In a supersonic wind tunnel, a supersonic nozzle that produces a supersonic airflow is a so-called Laval nozzle in which the cross-sectional area of a flow channel is first reduced and then expanded.
When the upstream / downstream pressure ratio of the air flow is sufficiently large, the air flow expands adiabatically in this enlarged flow path part to generate a supersonic air flow.At this time, the downstream air flow Mach number is the flow path cross-sectional area and flow path. It is known that it is well approximated by the ratio of the minimum cross-sectional area, and so-called one-dimensional theory holds. Therefore, the supersonic nozzle must set the shape of the wind tunnel wall according to the air flow Mach number at the nozzle outlet, and the conventional supersonic nozzle is
As shown in the vertical cross-sectional view of FIG. 5, a solid wall 14 made of a thin plate, which can be elastically changed, is formed at the tip of a rectifying cylinder 2 that creates a uniform flow 1.
The solid wall 14 is held by a plurality of hydraulic jacks 15, and the wall shape is set by the stroke of the hydraulic jacks 15.

However, in such an apparatus, the structure of the solid wall is complicated, it takes time and labor to set the individual Mach numbers, and when the nozzles are individually made according to the individual Mach numbers, they are produced. It is possible to realize only the Mach number of the existing nozzle, and it takes time and labor to replace this nozzle. Furthermore, in order to change the Mach number in the air flow, it is necessary to operate a complicated mechanism, and there is a dislike that it lacks quick effect.

[0004]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above circumstances, and it is possible to change the cross-sectional area of an air flow passage without changing the shape of the flow passage wall. An object of the present invention is to provide a wind tunnel capable of easily and accurately setting the cross-sectional area of the air flow passage according to the number.

[0005]

To this end, the present invention provides an air jet outlet upstream of a constant cross-section flow path wall in a wind tunnel in which the uniform flow velocity cross-sectional area is changed to control the uniform flow velocity. Alternatively, it is characterized in that a projection is provided and an airflow suction port is provided downstream to change the airflow channel cross-sectional area aerodynamically.

[0006]

In the wind tunnel of the present invention, a so-called aerodynamic nozzle is created by blowing the air jet from the air jet blowing port provided on the upstream side of the wall of the constant cross-section area and sucking the air stream from the air flow sucking port provided on the downstream side. Control the uniform flow velocity. Therefore, it is not necessary to change the nozzle shape depending on the Mach number, and the uniform flow velocity can be appropriately and easily controlled by controlling the flow rate and pressure of the blown air jet.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment of the wind tunnel of the present invention will be described. FIG. 1 is a longitudinal sectional view of the first embodiment, FIG. 2 is an explanatory view of a flow field in the vicinity of an air jet blowing port in the same as above, and FIG. FIG. 4 is an explanatory view of a flow field near the mouth, and FIG. 4 is a vertical sectional view of the second embodiment.

First, in FIG. 1 of the first embodiment, a constant cross-sectional area flow passage wall 3 is formed at the tip of a rectifying cylinder 2 which produces a uniform flow air flow 1. An air jet blowing port 4 is provided at an upstream position, and an air flow suction port 5 is provided at a downstream position. The air jet blowing port 4 and the air flow suction port 5 may each be singular, but they are plural in order to make the flow of the air flow streamline 10 smooth. Then, each air jet blow-in port 4 is connected to a high-pressure air storage tank 6, a valve 7 for controlling the pressure and flow rate of the air jet 11 is arranged in the middle thereof, and each air flow suction port 5 is connected to a vacuum tank 8. A valve 9 for controlling the flow rate and the pressure is arranged in the middle.
The valves 7 and 9 are controlled by a wind tunnel control computer.

In such a device, how the flow of the airflow streamline 10 changes when the air jet 11 is blown from the air jet blowing port 4 and sucked from the air flow suction port 5 will be described with reference to FIGS. 3 and 4. In FIG. 3, when the air jet 11 is blown from the air jet blowing port 4 perpendicularly to the airflow streamline 10, the airjet 11 is bent to the downstream side and accordingly the airflow streamline 10 separates from the constant cross-sectional area flow path wall 3. Can be bent. At this time, a separation area is formed immediately upstream and immediately downstream of the air jet 11, and a complicated flow field is formed. The shape of the outside of the airflow streamline 10 is determined by the divided streamline 12 that divides the airflow streamline 10 and the air jet 11. The shape of the divided streamline 12 changes according to the pressure and flow rate of the air jet 11, and The shape of the divided streamline 12 can be freely set by appropriately selecting these because it changes depending on the number of the blowing ports 4. In FIG. 4, when the air jet 11 is sucked by the air flow suction port 5, the flow path of the air flow streamline 10 is expanded, and the adiabatic expansion of the air flow is assisted to generate the air flow streamline 10 having a predetermined Mach number. ..

In this way, by blowing the air jet 11 from the air jet blowing port 4, the air flow streamline 10 of the uniform air flow 1 coming from the flow straightening cylinder 2 is narrowed, and then the air flow from the constant cross-sectional area flow passage wall 3 on the downstream side. The airflow streamline 10 narrowed by sucking out the airflow streamline 10 is expanded again, that is, by blowing and sucking out the air jets 11 upstream and downstream of the flow passage wall 3 near the constant cross-sectional area, so to speak, a Laval nozzle is formed, The uniform flow in the wind tunnel is adiabatically expanded in the expanded portion, and a supersonic airflow can be realized.

Next, referring to FIG. 4 of the second embodiment, instead of the above-mentioned air jet blowing port 4, a protrusion 13 is installed on the flow passage wall 3 of a constant cross-sectional area to reduce the airflow streamline 10. The reduced airflow streamline 10 is substantially expanded by positively sucking the airflow from the airflow suction port 5 located downstream, and realizes a supersonic airflow by adiabatic expansion. Both the projection 13 and the air jet blowing port 4 may be combined, and the height of the projection 13 and the length in the flow direction and the mounting position may be changed according to the Mach number to be generated. Good.

[0012]

In summary, according to the present invention, an air jet outlet or a projection is provided upstream of a constant cross-sectional area flow path wall in a wind tunnel in which the cross-sectional area of the uniform flow path is changed to control the uniform flow velocity. By providing an airflow suction port downstream and changing the airflow channel cross-sectional area aerodynamically,
The present invention provides a wind tunnel that can change the air flow passage cross-sectional area without changing the shape of the flow passage wall and can easily and accurately set the air flow passage cross-sectional area according to an arbitrary Mach number. It is extremely useful in industry.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a first embodiment of a wind tunnel of the present invention.

FIG. 2 is an explanatory diagram of a flow field in the vicinity of an air jet blowing port in the above.

FIG. 3 is an explanatory view of a flow field in the vicinity of the airflow suction port in the above.

FIG. 4 is a vertical sectional view of a second embodiment.

FIG. 5 is a vertical cross-sectional view of a conventional wind tunnel.

[Explanation of symbols]

 1 air flow 2 straightening tube 3 constant cross-sectional area flow path wall 4 air jet blowing port 5 air flow suction port 6 high pressure air storage tank 7 valve 8 vacuum tank 9 valve 10 air flow stream line 11 air jet 12 split stream line 13 protrusion

Claims (1)

[Claims] 1. In a wind tunnel for controlling a uniform flow velocity by changing the cross-sectional area of a uniform flow passage, an air jet outlet or a protrusion is provided upstream of a constant cross-section passage wall, and the air is sucked out downstream. A wind tunnel that is provided with a mouth to change the air flow passage cross-sectional area aerodynamically.