JP3189928B2 - Heavy piston driven shock wind tunnel and control method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy-piston-driven impact wind tunnel generally called a gun tunnel, and a control method thereof.

[0002]

2. Description of the Related Art As is well known, a wind tunnel generates a uniform airflow having a controlled wind speed, and the airflow is blown onto a model of an object moving in the air, such as an aircraft, an automobile, and a ship. This is an experimental device for investigating the influence of the airflow on the real object of the object using a similarity law.

[0003] Various types of wind tunnels have been proposed so far according to the magnitude of the generated wind speed.

[0004] Among them, as a high-speed wind tunnel in which experiments at a high Mach number can be performed, as shown in FIG. 2, a high-pressure chamber 1 filled with high-pressure air is blown out using a tapered Laval tube. By connecting the low pressure chamber or the exhaust device 3 via the nozzle 2 and opening the pressure regulating valve 4 provided between the high pressure chamber 1 and the blowing nozzle 2, 300 m A configuration has been proposed to generate an airflow that exceeds the speed of sound above / s.

[0005] However, this wind tunnel has a problem that the equipment becomes large-scale and the equipment cost increases.

Therefore, a wind tunnel shown in FIG. 3 has been proposed. This connects a high-pressure chamber 5 filled with a high-pressure driving gas and a low-pressure chamber 6 filled with a low-pressure working gas via a rupture membrane (rupture disk) 7 and the other end of the low-pressure chamber 6. A blowing nozzle 8 is provided on the side of the rupture membrane 7.
, An airflow exceeding the speed of sound is generated due to the pressure difference between the high-pressure chamber 5 and the low-pressure chamber 6.

According to this wind tunnel, it is possible to form an airflow in a low Mach number region, but there is a problem that the duration of the airflow is short.

Therefore, a wind tunnel shown in FIG. 4 has been proposed. This is generally called a shock wind tunnel, and a high-pressure chamber 9 as a driving cylinder filled with a high-pressure driving gas and a low-pressure chamber 10 as a working cylinder filled with a low-pressure working gas are interposed through a rupture membrane 11. At the other end of the low pressure chamber 10, a measurement chamber 13, which is evacuated by a vacuum pump 13 a via a quick opening / closing valve 12 a and a blowing nozzle 12 using a Laval tube, is arranged at the other end of the low pressure chamber 10. By breaking the membrane 11, the driving gas inside the high-pressure chamber 9 expands rapidly to generate a shock wave in the low-pressure chamber 10, and while the generated shock wave is reflected at the pipe end of the low-pressure chamber 10, the vicinity of this pipe end A high-temperature and high-pressure gas (3000 K, about 100 atm) is generated, and the high-temperature and high-pressure gas is blown into the measurement chamber 13 from the nozzle 12 to form a hypersonic flow for about several ms.

[0009] However, in this shock wind tunnel, although the temperature of the high-temperature and high-pressure gas obtained becomes high, it is difficult to increase the pressure of the high-temperature and high-pressure gas.
There was a problem that it was difficult to extend beyond.

Therefore, as an improved shock wind tunnel, a slidable piston 1 is inserted into a low-pressure chamber 10 as shown in FIG.
4 is provided internally, and instead of forming a high-temperature and high-pressure gas by a shock wave when the rupture membrane 11 is broken, the isoenthalpy compression with a small thermal loss by the piston 14 is performed to reduce the duration of the airflow. A wind tunnel that expands to about 200 ms has been proposed. In this specification, such a type of wind tunnel is referred to as a heavy-piston-driven impact wind tunnel (gun tunnel).

The operating conditions of the heavy piston driven type wind tunnel are as follows:
It is determined by the piston weight and the piston drive pressure ratio.
In this type of heavy-piston-driven shock wind tunnel, pressure is increased without increasing the temperature of the resulting high-temperature and high-pressure gas, as compared to a shock wind tunnel, because isenthalpy compression with low thermal loss is performed. Therefore, the duration of the airflow can be extended.

[0012]

By the way, depending on the object of the experiment, there is a case where it is desired to conduct an experiment by forming a supersonic airflow having a Mach number of about 1 to 4 at normal temperature and normal pressure in the measurement chamber.

However, in the wind tunnel shown in FIG. 2 or FIG. 3, a supersonic airflow having a Mach number of about 1 to 4 can be formed, but the temperature of the airflow ejected from the blowing nozzle drops extremely below room temperature. Resulting in. In order to make the temperature of the airflow about normal temperature, the temperature of the high-pressure gas in the high-pressure chamber may be increased by using, for example, a heater, but in consideration of the heating capability of the heater, etc., the heating is surely performed to the predetermined temperature. It is not easy to do.

Further, in the shock wind tunnel shown in FIG. 4 and the heavy piston drive type shock wind tunnel shown in FIG. 5, the total enthalpy becomes too high, so that the temperature and pressure of the air flow become too high. Makes it difficult to eliminate the effects of

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. For example, it is possible to form a supersonic airflow having a Mach number of about 1 to 4 at normal temperature and normal pressure. An object of the present invention is to provide a heavy piston driven shock wind tunnel capable of forming a supersonic airflow at normal temperature and normal pressure, and a method of controlling the heavy piston driven shock wind tunnel capable of forming a supersonic airflow.

[0016]

SUMMARY OF THE INVENTION A heavy-piston driven shock wind tunnel according to the present invention has a high-pressure chamber filled with a high-pressure driving gas and a slidable piston inside and is filled with a low-pressure working gas. A cylindrical low-pressure chamber connected to the high-pressure chamber, and a rupture membrane separating the high-pressure chamber and the low-pressure chamber;
The low-pressure chamber includes a blow-off nozzle with a quick opening / closing valve provided at an end of the both ends of the low-pressure chamber that is not connected to the high-pressure chamber, and a measurement chamber connected to the blow-off nozzle and suctioned by vacuum. A plenum chamber having a heavy piston drive type impact wind tunnel, further comprising an orifice provided between the low pressure chamber and the blow nozzle, for controlling the temperature and pressure of the high pressure gas generated in the low pressure chamber before blowing. It is characterized by having.

[0017] A method for controlling a heavy piston driven shock wind tunnel according to the present invention comprises: a high pressure chamber filled with a high pressure driving gas;
It has a slidable piston inside and is filled with a low-pressure working gas, and generates a shock wave inside the low-pressure chamber by breaking a rupture membrane separating the cylindrical low-pressure chamber connected to the high-pressure chamber. By driving the piston, a high-pressure gas is generated inside a blow-off nozzle side with a quick open / close valve connected to an end of the both ends of the low-pressure chamber that is not connected to the high-pressure chamber. A method for controlling a heavy-piston driven shock wind tunnel in which the high-pressure gas is blown out as a supersonic airflow into a vacuum suctioned measurement chamber connected to the blow-out nozzle by opening the quick open / close valve, Providing a plenum chamber having an orifice for controlling the temperature and pressure of the high pressure gas generated in the low pressure chamber before blowing between the chamber and the blowing nozzle; And it is characterized in controlling the temperature and pressure of the air flow ejected.

[0018]

According to the heavy-piston driven shock wind tunnel and the control method therefor according to the present invention, the temperature and pressure of the high-temperature and high-pressure gas generated in the low-pressure chamber are set to, for example, normal temperature and normal pressure between the low-pressure chamber and the blow nozzle. Since a plenum chamber having an orifice to be controlled is provided, a pressure loss is given to the high-pressure gas by the orifice in the plenum chamber, so that the temperature of the supersonic air flow ejected from the quick opening / closing valve provided in the blowing nozzle is increased. And the pressure is controlled.

Further, in the heavy-piston-driven impact wind tunnel according to the present invention, the orifice is changeable because the orifice is replaceably installed.

Therefore, by changing the orifice diameter by replacing the orifice, the state of the stagnation point in the measurement chamber is adjusted, and the operating conditions of the wind tunnel are controlled with a very high degree of freedom. For example, control is performed at normal temperature and normal pressure.

[0021]

An embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing an example of the configuration of a heavy-piston driven shock wind tunnel according to the present invention.
1A is an overall view, and FIG. 1B is an enlarged view of a portion surrounded by a broken line in FIG.

As shown in FIG. 1A, a driving cylinder 15 which is a high-pressure chamber filled with a high-pressure driving gas is arranged. A working cylinder 18 having a slidable piston 16 and being filled with a low-pressure working gas is connected to the working cylinder 18. Both the driving cylinder 15 and the operating cylinder 18 are hollow cylindrical members, and a shock wave is generated in the operating cylinder 18 due to a pressure difference between the driving cylinder 15 and the operating cylinder 18 by breaking the rupture membrane 17.

Inside the working cylinder 18, a piston 16 which is moved in the longitudinal direction of the working cylinder 18 by using the above-mentioned shock wave as a driving source while sliding on the inner surface is provided.

As shown in FIGS. 1 (a) and 1 (b), the end of the working cylinder 18 which is not connected to the drive cylinder 15 is compressed by a piston 16 and is generated. For example, a plenum chamber 23 having an orifice 22 for controlling the temperature and pressure of a high-temperature and high-pressure gas of about 80 to 100 atmospheres is provided.

In the present embodiment, the orifice 22 is fastened to the flange surface of the plenum chamber 23 and can be replaced with another orifice having a different diameter. The diameter of the orifice 22 is appropriately set according to the control conditions of the high-temperature and high-pressure gas.

The orifice 22 has the function of reducing the flow rate of the high-pressure gas generated in the working cylinder 18 and controlling the conditions of the airflow blown out from a blowout nozzle 20 described later and formed in the measurement chamber 21.

As shown in FIG. 1A, an outlet nozzle 20 with a quick open / close valve 19 is installed in the plenum chamber 23. Although a non-diaphragm valve using an electromagnetic valve is used as the quick opening / closing valve, a rupture membrane may be used. Further, as the blowing nozzle 20, a nozzle using a known Laval tube is used.

A vacuum measuring chamber 21 is connected to the blowing nozzle 20. The measurement chamber 21 is provided with a vacuum pump 24 during measurement.
And the duration of the airflow is maintained at about 200 ms.

In the measuring room 21, a model to be measured such as an aircraft is arranged. In this embodiment, the model (not shown) is configured to be held by a jig. However, the model may be naturally dropped or fly in accordance with the timing at which the airflow occurs. By using no jig or the like, more accurate experimental results can be obtained.

The procedure for conducting a wind tunnel experiment using the heavy piston driven shock wind tunnel according to the present invention having the above configuration, that is, the method for controlling the heavy piston driven shock wind tunnel according to the present invention, is described above with reference to FIG. This will be described with reference to FIG. 1A and FIG.

The inside of the driving cylinder 15 is pressurized to a high pressure, and the inside of the working cylinder 18 is pressurized to a low pressure. The piston 16 is arranged at a predetermined position on the drive cylinder 15 side in the operation cylinder 18. Further, the quick opening / closing valve 19 is closed, and the inside of the measuring chamber 21 is evacuated by the vacuum pump 24.

In this state, the rupture membrane 17 is broken. Then, the driving gas in the driving cylinder 15 expands rapidly toward the inside of the operating cylinder 18 due to the pressure difference generated between the driving cylinder 15 and the operating cylinder 18, and a shock wave is generated inside the operating cylinder 18. The shock wave causes the piston 16 to slide at high speed inside the working cylinder 18, and within the plenum chamber 23 provided on the measurement chamber 21 side of the working cylinder 18, the working cylinder 18 of the two spaces partitioned by the orifice 22. A high-pressure gas of about 80 to 100 atm is retained on the side.

In this manner, high-temperature and high-pressure gas is stored in the plenum chamber 23 on the side of the working cylinder 18 of the two spaces separated by the orifice 22. Is opened, it is ejected from the ejection nozzle 20 into the measurement chamber 21 to form a supersonic airflow. Prior to the ejection from the blowing nozzle 20, the high-temperature and high-pressure gas passes through the orifice 22 provided in the plenum chamber 23, so that a pressure loss is given by the orifice 22, and the pressure and temperature of the airflow are reduced to normal temperature and normal pressure. Is controlled.

In this way, the pressure and temperature of the airflow formed in the heavy-piston-driven impact wind tunnel according to the present invention are controlled, and for example, it is possible to generate an airflow at normal temperature and normal pressure.

When the conditions of the driving gas filled in the high-pressure chamber are different, the obtained airflow is controlled to normal temperature and normal pressure by replacing the orifice and changing the orifice diameter appropriately.

[0036]

As described in detail above, in the heavy-piston driven shock wind tunnel according to the present invention, since the plenum chamber having the orifice is provided between the low-pressure chamber and the blow nozzle, the high temperature blown from the blow nozzle is high. It is possible to control the temperature and pressure of the enthalpy of the high-pressure gas. Also, the orifices are interchangeable. Therefore, by changing the orifice diameter by replacing the orifice, the state of the stagnation point of the wind tunnel in the measurement chamber is adjusted, and it becomes possible to control the operating condition of the wind tunnel with extremely high degree of freedom. It is possible to control the airflow to normal temperature and normal pressure.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the structure of a heavy-piston driven shock wind tunnel according to the present invention. FIG. 1 (a) is an overall view, FIG.
FIG. 2B is an enlarged view of a portion indicated by a broken line in FIG.

FIG. 2 is an explanatory diagram showing an example of the structure of a conventional high-speed wind tunnel.

FIG. 3 is an explanatory view showing another example of the structure of the conventional high-speed wind tunnel.

FIG. 4 is an explanatory view showing a structure of a conventional shock wind tunnel.

FIG. 5 is an explanatory view showing the structure of a conventional heavy-piston driven shock wind tunnel called a gun tunnel.

[Explanation of symbols]

 Reference Signs List 15 driving cylinder (high pressure chamber) 16 piston 17 rupture membrane 18 operating cylinder (low pressure chamber) 19 quick opening / closing valve 20 blowing nozzle 21 measuring chamber 22 orifice 23 plenum chamber 24 vacuum pump

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-307344 (JP, A) JP-A-7-218381 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01M 9/04

Claims (3)

(57) [Claims] A high-pressure chamber filled with a high-pressure driving gas;
A cylindrical low-pressure chamber which has a slidable piston therein and is filled with a low-pressure working gas and is connected to the high-pressure chamber; a rupture membrane separating the high-pressure chamber and the low-pressure chamber; and both ends of the low-pressure chamber A heavy-piston-driven shock wind tunnel, comprising: a blow-off nozzle provided with a quick opening / closing valve provided at an end on a side not connected to the high-pressure chamber; and a vacuum-suctioned measurement chamber connected to the blow-out nozzle. And a plenum chamber provided between the low-pressure chamber and the blow-off nozzle and having an orifice for controlling the temperature and pressure of the high-pressure gas generated in the low-pressure chamber before blowing. Heavy piston driven wind tunnel. 2. The heavy piston driven wind tunnel of claim 1, wherein said orifice is replaceable. 3. A high-pressure chamber filled with a high-pressure driving gas,
It has a slidable piston inside and is filled with a low-pressure working gas, and generates a shock wave inside the low-pressure chamber by breaking a rupture membrane separating the cylindrical low-pressure chamber connected to the high-pressure chamber. By driving the piston, a high-pressure gas is generated inside a blow-off nozzle side with a quick open / close valve connected to an end of the both ends of the low-pressure chamber that is not connected to the high-pressure chamber. A method for controlling a heavy-piston driven shock wind tunnel in which the high-pressure gas is blown out as a supersonic airflow into a vacuum suctioned measurement chamber connected to the blow-out nozzle by opening the quick open / close valve, Providing a plenum chamber having an orifice for controlling the temperature and pressure of the high pressure gas generated in the low pressure chamber before blowing between the chamber and the blowing nozzle; The method of the heavy piston driven shock tunnel, characterized by controlling the temperature and pressure of the air flow ejected.