JPH07218381A - Apparatus and method for controlling waveform in shock wind-tunnel - Google Patents

Abstract

PURPOSE:To provide a waveform control apparatus and the waveform control method for a shock wind-tunnel which can elongate the duration of steady air flow and can form the air flow accompanying high-frequency pressure fluctuation by controlling the waveforms before and after expansion. CONSTITUTION:A porous plate 21 is provided in front of the moving end of a low-pressure chamber 9, wherein a piston is moved at a high speed. High-frequency pressure fluctuation is formed of a shock wave formed at the output side of many holes and the reflected wave from the end of the low pressure chamber. The compressive high-speed air flow generating the high-frequency pressure fluctuation is formed by expanding the pressure fluctuation. Thus, the waveform of the air flow formed in the shock wind tunnel can be simply controlled, and the air flow and the like accompanying the high-frequency pressure can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock wave tunnel waveform control device and waveform control method, and controls the waveform of a shock wave to eliminate the effects of air flow accompanied by high frequency pressure fluctuations other than steady flow and reflected waves which disturb the waveform and maintain the waveform. It is designed to extend the time.

[0002]

2. Description of the Related Art A wind tunnel generates a uniform air flow whose wind speed is controlled, and a model such as an object moving in the air such as an aircraft, an automobile, a ship or a model such as a building is put in the air flow to generate an air flow. This is an experimental device for investigating the influence of the above, and various kinds of wind tunnels have been proposed so far according to the magnitude of the generated wind speed.

Among them, as a high-speed wind tunnel capable of producing a high Mach number air flow, as shown in FIG. 4 (a), a high pressure chamber 1 filled with high pressure air is provided with a blowing nozzle 2 of a tapered shape or the like. The low pressure chamber or the exhaust device 3 is connected through the opening, and the pressure regulating valve 4 provided between the high pressure chamber 1 and the blowing nozzle 2 is opened, so that the inside of the low pressure chamber or the exhaust device 3 is 300 m / s or more. Some are designed to generate an air flow that exceeds the speed of sound.

However, in this high-speed wind tunnel, in order to create an air flow with a large Mach number, the pressure of the air with which the high-pressure chamber 1 is filled must be increased, which requires a large-scale facility such as a high-pressure compressor. However, there was a problem that the equipment cost would be expensive.

Therefore, a wind tunnel shown in FIG. 4 (b) has been proposed as a high-speed wind tunnel capable of obtaining a high-speed air flow relatively easily. A high-pressure chamber 5 for filling high-pressure gas and a low-pressure chamber 6 for reducing the pressure are proposed. The gas in the high-pressure chamber 5 is expanded into the low-pressure chamber 6 by the pressure difference between the high-pressure chamber 5 and the low-pressure chamber 6 by connecting the membrane 7 through the diaphragm 7, and the air flow exceeding the sonic velocity. I am trying to generate.

According to this high-speed wind tunnel, it is possible to form an air flow in a low Mach number region, but if an attempt is made to obtain a high-speed air flow having a short duration of the high-speed air flow and a large Mach number, the high pressure chamber 5 There is a problem that the pressure of the gas to be filled must be increased, and further, the gas expands to the high pressure chamber 5 side after the diaphragm 7 is broken, resulting in poor efficiency.

Therefore, a wind tunnel shown in FIG. 4 (c) has been proposed as a wind tunnel capable of lengthening the duration of high-speed airflow, and is generally called an impact wind tunnel.

In this shock wind tunnel, a high pressure chamber 8 for filling high pressure gas and a low pressure chamber 9 are connected via a diaphragm 10, and a rapid opening / closing valve 11 and a Laval tube are used at the tip of the low pressure chamber 9. A measurement chamber 14 that is vacuum-sucked by a vacuum pump 13 via a blow-out nozzle 12 is arranged, and when the diaphragm 10 is broken, the driving gas inside the high-pressure chamber 8 expands rapidly to the low-pressure chamber 9. A shock wave is generated and the generated shock wave compresses the gas in the low pressure chamber 9 to generate a high temperature and high pressure gas (3000 K, about 100 atm) near the tube end, and the high temperature and high pressure gas is supplied from the nozzle 12 to the measurement chamber 1
By expanding it to 4, a hypersonic flow is formed for a time of several ms.

Furthermore, as an impact wind tunnel in the case of requiring an air flow with a high Mach number and extending the duration, as shown in FIG. 4 (d), it slides inside the low pressure chamber 9. Rather than forming a high-temperature high-pressure gas with a shock wave when the diaphragm 10 is breached, the piston 15 is driven at a high speed to perform compression with less thermal loss to achieve higher temperature. A high-pressure gas is obtained, which is expanded to obtain a high-speed air stream, and the duration is extended to about 200 ms.

In such an impact wind tunnel, high-temperature high-pressure gas can be easily obtained because the piston 15 performs isentropic compression with less thermal loss, and a steady air flow with a high Mach number can be obtained. .

[0011]

However, not only the steady high-speed air flow but also the one moving in the shock wave depending on the object to be tested using such two types of shock wind tunnels, the air flow created in the shock wind tunnel There is a case where it is desired to make the high frequency pressure fluctuation, but in the conventional shock wind tunnel, the air flow accompanied by the high frequency pressure fluctuation could not be created although the device for obtaining the steady flow was made.

In the conventional shock wind tunnel in which the piston is used for adiabatic compression, part of the expansion wave is reflected by the piston and disturbs the air flow, so that the steady flow has a short duration and stable experiments are performed. It is desired to have a longer duration.

The present invention has been made in order to solve the problems of the above-mentioned conventional techniques, and a shock wave tunnel waveform control device and waveform capable of producing not only a steady air flow but also an air flow accompanied by a high frequency pressure fluctuation. It is intended to provide a control method.

Another object of the present invention is to provide a shock wave tunnel waveform control device and waveform control method capable of extending the duration by delaying the arrival of a reflected wave that affects the duration.

[0015]

According to a first aspect of the present invention, there is provided a shock wave tunnel waveform control device in which a high-pressure drive gas in a high-pressure chamber is rapidly expanded to rapidly move a piston in the low-pressure chamber to generate a high-temperature and high-pressure fluid. Then, in a shock wind tunnel that expands this fluid to obtain a high-speed airflow, a shock wave formed on the exit side of the porous body and a reflected wave from the end of the low-pressure chamber are formed in front of the moving end of the low-pressure chamber in which the piston moves at high speed. It is characterized in that a perforated plate that creates an air flow having a high-frequency pressure fluctuation waveform is provided.

According to a second aspect of the present invention, there is provided a shock wave tunnel waveform control method in which the high-pressure drive gas in the high-pressure chamber is rapidly expanded, the piston in the low-pressure chamber is moved at high speed, and a high-temperature and high-pressure fluid is obtained. In an impact wind tunnel that expands a fluid to obtain a high-speed air flow, a perforated plate is provided in front of the moving end of the low-pressure chamber in which the piston moves at high speed, and the shock wave formed on the exit side of these perforations and the reflection reflected at the end of the low-pressure chamber It is characterized in that high-frequency pressure fluctuations are created by waves and the fluid is expanded to create a compressible high-speed airflow that causes high-frequency pressure fluctuations.

Further, according to the third aspect of the present invention, the waveform control device for an impact wind tunnel rapidly expands the high pressure driving gas in the high pressure chamber to move the piston in the low pressure chamber at high speed to obtain a high temperature and high pressure fluid. In an impact wind tunnel for expanding a fluid to obtain a high-speed airflow, a second low-pressure chamber is connected to an end of the low-pressure chamber, and one or more holes are formed in front of a moving end of a piston of the low-pressure chamber that moves at high speed. A perforated plate is provided to delay the time for the expansion wave accompanying the expansion of the fluid to the second low-pressure chamber to reach the high-speed airflow of the reflected wave at the piston, and to extend the duration by preventing the waveform from being disturbed. It is characterized by that.

According to a fourth aspect of the present invention, there is provided a shock wave tunnel waveform control method, wherein the high-pressure drive gas in the high-pressure chamber is rapidly expanded, the piston in the low-pressure chamber is moved at high speed, and a high-temperature and high-pressure fluid is obtained. In a shock wind tunnel in which a fluid is expanded into a second low pressure chamber to generate a shock wave, and then the obtained fluid is further expanded to obtain a high-speed airflow, one or a plurality of pressures are provided before the moving end of the low-pressure chamber in which the piston moves at high speed. A perforated plate having holes is provided to delay the time when the expansion wave accompanying the expansion of the fluid to the second low pressure chamber is reflected by the piston and reaches the high speed fluid to extend the duration of the high speed air flow. It is characterized by being designed.

[0019]

According to the waveform control device and the waveform control method for an impact wind tunnel according to the first and second aspects of the present invention, the high-pressure drive gas in the high-pressure chamber is rapidly expanded to move the piston in the low-pressure chamber at high speed to generate a high-temperature and high-pressure gas. When a compressed fluid is obtained and the compressed fluid is expanded to obtain a high-speed air flow, a perforated plate is provided in front of the moving end of the low-pressure chamber in which the piston moves at high speed. A high-frequency pressure fluctuation is created by the shock wave and the reflected wave reflected at the end of the low-pressure chamber, and by expanding this, a compressible high-speed airflow that causes the high-frequency pressure fluctuation is created.

Thus, the waveform of the air flow created in the impact wind tunnel can be easily controlled, and the air flow accompanied by the high frequency pressure fluctuation can be obtained.

According to the waveform control device and the waveform control method for an impact wind tunnel according to claims 3 and 4 of the present invention, the high-pressure drive gas in the high-pressure chamber is rapidly expanded, and the piston in the low-pressure chamber is moved at high speed to increase the temperature. After obtaining a high-pressure fluid and expanding the fluid into the second low-pressure chamber to create a shock wave, and further expanding the obtained fluid to obtain a high-speed airflow, the moving end of the low-pressure chamber in which the piston moves at high speed A perforated plate having one or a plurality of holes formed in front is provided, and a part of the air flow expanding from the low pressure chamber toward the second low pressure chamber is reflected by the piston of the low pressure chamber to reach the high speed fluid. By delaying the time with holes in the perforated plate, the duration of the high-speed airflow is extended.

[0022]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a main part according to an embodiment of a waveform control device for an impact wind tunnel according to claim 1 of the present invention, showing front and rear of a blowout nozzle of the impact wind tunnel shown in FIG. 4 (d). Is.

In this shock wind tunnel waveform control device 20, the porous plate 21 is provided in front of the moving end (right end in FIG. 1) of the low pressure chamber 9 in which the piston 15 of the shock wind tunnel shown in FIG. 4 (d) is mounted. Installed.

The low-pressure chamber 9 in front of the perforated plate 21
A quick opening / closing valve 11 is attached to the tip of the nozzle and a blowout nozzle 12 is attached.

Although not shown in FIG. 1, the low pressure chamber 9
The configuration of the high-pressure chamber arranged on the upstream side of the membrane through the diaphragm and the measurement chamber provided downstream of the blowout nozzle 12 and vacuum-sucked by the vacuum pump are the same as those in FIG. 4 (d) already described. Yes, and will be described below using the numbers (see FIG. 4).

A description will be given of the operation of the shock-tunnel waveform control device 20 configured as described above and a method of controlling the shock-tunnel waveform.

First, as a preparation before the experiment, the high pressure chamber 8 is filled with compressed air as a driving gas by using a small compressor or the like. The pressure for filling the high-pressure chamber 8 with compressed air is appropriately determined according to the measurement conditions such as the finally required high-speed air flow. Further, the piston 15 in the low-pressure chamber 9 is moved to the end portion on the high-pressure chamber 8 side, and the diaphragm 10 is formed between the piston 15 and the high-pressure chamber 8.
Is attached and closed, and the rapid opening / closing valve 11 at the tip of the low pressure chamber 9 is closed.

Further, after the model to be measured is installed in the measuring chamber 14, the inside of the measuring chamber 14 is vacuum-sucked by the vacuum pump 13 and the inside of the low pressure chamber 9 is also brought to a predetermined low pressure state.

After the preparation is completed in this way, the diaphragm 10 that divides the high pressure chamber 8 and the low pressure chamber 9 is broken.

Then, the pressure difference between the high pressure chamber 8 and the low pressure chamber 9 causes the compressed air in the high pressure chamber 8 to rapidly expand, thereby driving the piston 15 at a high speed and the piston 15
The air in the low-pressure chamber 9 in front of is rapidly compressed, and a high-temperature high-pressure gas in an adiabatic compression state with less thermal loss is produced.

When this high-temperature and high-pressure gas reaches the porous plate 21 before the moving end of the low-pressure chamber 9, a shock wave is formed in front of the porous plate 21 due to expansion when passing through the porous portion. The shock wave from each hole is reflected at the tip of the low-pressure chamber 9, and the shock wave and the reflected wave are combined to generate high-temperature high-pressure gas with high-frequency pressure fluctuation at the tip of the low-pressure chamber 9.

In this way, the rapid opening / closing valve 11 is opened and the blow-out nozzle 12 expands it while the high-temperature high-pressure gas accompanied by the high-frequency pressure fluctuation is produced.

Then, the gas accompanied by the high-frequency pressure fluctuation expands to form a supersonic airflow in the measurement chamber 14, and the supersonic airflow also contains the high-frequency pressure fluctuation as it is. Can create an air flow.

Therefore, it is possible to conduct an experiment while reproducing a state in which a high-speed flying body launched from a tubular guide flies in a shock wave.

Further, since an air flow accompanied by high-frequency pressure fluctuations is created, it suffices to install the perforated plate 21, the structure is simple, and high-pressure gas can be easily considered.

Further, it is possible to control the high frequency pressure fluctuation waveform generated in the measurement chamber 14 by the number and size of the holes of the perforated plate 21, the distance from the moving end of the low pressure chamber 9 or the like, and different pressure fluctuations can be controlled. Can be produced.

Next, another embodiment of the waveform control device for an impact wind tunnel according to the present invention will be described with reference to FIG.

The waveform control device 30 of the impact wind tunnel is different from the device 20 of the embodiment only in the structure in which the quick opening / closing valve 11 is removed.
A high-temperature high-pressure gas accompanied by high-frequency pressure fluctuations is created at the tip of the low-pressure chamber 9 by the shock wave when passing through the chamber and the reflected wave reflected at the tip of the low-pressure chamber 9, and this gas expands from the blowout nozzle 12 A supersonic airflow with high frequency pressure fluctuations can be created in the chamber 14.

Therefore, the structure is further simplified, and the high-frequency pressure fluctuation waveform can be controlled to create an air flow with high-frequency pressure fluctuation in the measurement chamber 14.

Next, one embodiment of the waveform control device and the waveform control method for an impact wind tunnel according to claims 3 and 4 of the present invention will be described with reference to FIG.

In this embodiment, by controlling the waveform, the duration of the stationary air flow created in the measuring chamber 14 is extended.

In the shock wave tunnel waveform control device 40, the second low pressure chamber 42 is further provided at the tip of the low pressure chamber 9 via the diaphragm 41.
Are connected, and the blowing nozzle 12 and the measurement chamber 14 are installed at the tip of the second low-pressure chamber 42. The other basic structure is the same as that of the impact wind tunnel of FIG. 4D.

In the percussion wind tunnel waveform control device 40, one or a plurality of holes are formed in front of the moving end (the right end in the figure) of the piston 15 in the low pressure chamber 9 in order to control the waveform.
(In the illustrated example, it is a perforated plate.).
The rest of the configuration is the same as that of the above-mentioned embodiment, so its explanation is omitted.

The operation of the waveform control device 40 for an impact wind tunnel thus configured and the method for controlling the waveform of an impact wind tunnel will be described.

First, as a preparation before the experiment, the high pressure chamber 8 is filled with compressed air as a driving gas by using a small compressor or the like. The pressure for filling the high-pressure chamber 8 with compressed air is appropriately determined according to the measurement conditions such as the finally required high-speed air flow. Further, the piston 15 in the low pressure chamber 9 is moved to the end on the high pressure chamber 9 side, and the diaphragms 10 and 41 are attached to the high pressure chamber 8 and between the low pressure chamber 9 and the second low pressure chamber 42, respectively. Put it in a closed state.

Further, after the model to be measured is installed in the measuring chamber 14, the inside of the measuring chamber 14 is vacuum-sucked by the vacuum pump 13, and the inside of the low pressure chamber 9 and the second low pressure chamber 42 are also sucked.
The inside is also set to a predetermined low pressure.

After the preparation is completed in this way, the diaphragm 10 that divides the high pressure chamber 8 and the low pressure chamber 9 is broken.

Then, due to the pressure difference between the high pressure chamber 8 and the low pressure chamber 9, the compressed air in the high pressure chamber 8 expands rapidly, which drives the piston 15 at high speed and the piston 15
The air in the low-pressure chamber 9 in front of is rapidly compressed, and a high-temperature high-pressure gas in an adiabatic compression state with less thermal loss is produced.

After passing through the porous portion of the perforated plate 43 before the moving end of the low pressure chamber 9, the high temperature and high pressure gas further breaks the diaphragm 41 and expands toward the second low pressure chamber 42.

Then, a shock wave is formed in the forward direction, which is compressed and high-temperature high-pressure gas is produced at the tip of the second low-pressure chamber 42. This high-temperature high-pressure gas is expanded by the blow-out nozzle 12 and is kept stationary in the measurement chamber 14. A high velocity air stream is formed.

The duration of the high-speed airflow formed in the measuring chamber 14 is such that the diaphragm 41 between the low pressure chamber 9 and the second low pressure chamber 42 is broken to generate a shock wave, and at the same time, the piston 15 expands toward the tip. The time required for the reflected expansion wave to reach the tip of the second low pressure chamber 42 is determined by the conventional perforated plate 4
When No. 3 is not installed, the duration becomes T1 due to the expansion wave shown in FIG.

On the other hand, in this shock wind tunnel waveform control device 40, since the hole plate 43 is installed in front of the moving end of the piston 15 in the low pressure chamber 9, the expansion wave expanding by the diaphragm 41 is applied to the hole plate 43. After passing through the hole of No. 4, the surface of the piston 15 reflects and becomes a reflected expansion wave, but the development of the expansion wave can be suppressed by the resistance required to pass through the hole of the hole plate 43.
It is possible to delay the time for the reflected expansion wave to reach the tip of the second low pressure chamber 42, whereby the duration time can be extended to T, as shown in FIG.

By installing the perforated plate 43 in this way,
The waveform of the reflected expansion wave can be controlled, and thus the duration of the steady air flow formed in the measurement chamber 14 can be extended.

Therefore, the duration can be extended as compared with the conventional impact wind tunnel, and the experiment in the impact wind tunnel becomes easier.

Further, since it is only necessary to install the perforated plate 43 for extending the duration, the structure is simple and the high pressure gas can be easily considered.

[0056]

As described above in detail with reference to the embodiments, according to the waveform control device and the waveform control method for an impact wind tunnel according to claims 1 and 2 of the present invention, the high-pressure drive gas in the high-pressure chamber is rapidly changed. When expanding and moving the piston in the low pressure chamber at high speed to obtain high temperature and high pressure compressed fluid and expanding this compressed fluid to obtain high speed air flow, a perforated plate is provided in front of the moving end of the low pressure chamber where the piston moves at high speed. I did so,
A high-frequency pressure fluctuation is created by the shock wave formed on the exit side of these perforations and the reflected wave reflected at the end of the low-pressure chamber, and by expanding this, a compressible high-speed air flow that causes the high-frequency pressure fluctuation can be easily created. .

Thus, the waveform of the air flow created in the shock wind tunnel can be easily controlled, and the air flow accompanied by the high frequency pressure fluctuation can be obtained to conduct the wind tunnel experiment.

According to the waveform control device and the waveform control method for an impact wind tunnel according to claims 3 and 4 of the present invention, the high-pressure drive gas in the high-pressure chamber is rapidly expanded to move the piston in the low-pressure chamber at a high speed to increase the temperature. After obtaining a high-pressure fluid and expanding the fluid into the second low-pressure chamber to create a shock wave, and further expanding the obtained fluid to obtain a high-speed airflow, the moving end of the low-pressure chamber in which the piston moves at high speed Since the perforated plate having one or a plurality of holes formed in front is provided, a part of the air flow expanding from the low pressure chamber toward the second low pressure chamber is controlled by the control of the reflective expansion group by the perforated plate. It is possible to delay the time required for the high-speed fluid to be reflected by the piston to reach the high-speed fluid, and to extend the duration of the steady high-speed air flow.

[Brief description of drawings]

1 is a schematic configuration diagram of a main portion according to an embodiment of a waveform control device for an impact wind tunnel according to claim 1 of the present invention, showing the front and rear of a blowout nozzle of the impact wind tunnel shown in FIG. 4 (d). It is a thing.

FIG. 2 is a schematic configuration diagram of a main part according to another embodiment of the waveform control device for an impact wind tunnel according to claim 1 of the present invention, which is before and after the blowing nozzle of the impact wind tunnel shown in FIG. 4 (d). Is shown.

FIG. 3 is a schematic configuration diagram of an embodiment of a waveform control device for an impact wind tunnel according to claim 3 of the present invention and an explanatory diagram comparing the duration with a conventional device.

FIG. 4 is an explanatory view showing structures of a conventional high speed wind tunnel and impact wind tunnel.

[Explanation of symbols]

 8 High-pressure chamber 9 Low-pressure chamber 10 Diaphragm 11 Rapid opening / closing valve 12 Blow-out nozzle 13 Vacuum pump 14 Measuring chamber 15 Piston 20 Waveform controller for shock wind tunnel 21 Perforated plate 30 Waveform controller for shock wind tunnel 41 Waveform controller for shock wind tunnel 41 Septum 42 Second low-pressure chamber 43 Perforated plate T Duration

Claims (4)

[Claims] 1. A shock wind tunnel in which a high-pressure drive gas in a high-pressure chamber is rapidly expanded to move a piston in a low-pressure chamber at high speed to obtain a high-temperature and high-pressure fluid, and the fluid is expanded to obtain a high-speed air flow, wherein the piston is A shock characterized in that a perforated plate is provided in front of the moving end of the low-pressure chamber that moves at high speed to create an air flow having a high-frequency pressure fluctuation waveform by the shock wave formed on the exit side of the porous and the reflected wave from the end of the low-pressure chamber. Wind tunnel waveform controller. 2. An impact wind tunnel in which a high-pressure drive gas in a high-pressure chamber is rapidly expanded to move a piston in a low-pressure chamber at high speed to obtain a high-temperature and high-pressure fluid, and the fluid is expanded to obtain a high-speed air flow A perforated plate is provided in front of the moving end of the low-pressure chamber that moves at high speed, and a high-frequency pressure fluctuation is created by the shock wave formed on the exit side of these perforations and the reflected wave reflected at the end of the low-pressure chamber, and this fluid is expanded to generate high-frequency waves. A method for controlling a waveform of an impact wind tunnel, characterized in that a compressible high-speed air flow that causes pressure fluctuation is created. 3. A low pressure chamber in an impact wind tunnel for rapidly expanding a high pressure driving gas in a high pressure chamber to move a piston in a low pressure chamber at a high speed to obtain a high temperature and high pressure fluid and expanding the fluid to obtain a high speed airflow. The second low pressure chamber is connected to the end of the low pressure chamber, and one or a plurality of holes are formed in front of the moving end of the low pressure chamber where the piston moves at high speed, so that the second low pressure chamber expands with the expansion of the fluid. A waveform control device for an impact wind tunnel, characterized in that a perforated plate is provided for delaying the arrival time of the reflected wave of the wave at the high-speed airflow to prevent the waveform from being disturbed, thereby extending the duration. 4. A high-pressure drive gas in the high-pressure chamber is rapidly expanded to move a piston in the low-pressure chamber at a high speed to obtain a high-temperature and high-pressure fluid, and the fluid is expanded to a second low-pressure chamber to generate a shock wave. In an impact wind tunnel that further expands the obtained fluid to obtain a high-speed airflow, a hole plate having one or a plurality of holes is provided in front of the moving end of the low-pressure chamber in which the piston moves at high speed, A method for controlling a waveform of an impact wind tunnel, characterized in that the expansion wave resulting from the expansion of the fluid is reflected by the piston and is delayed in reaching the high-speed fluid to extend the duration of the high-speed air stream.