JPH08166317A - Nozzle for high-temperature wind tunnel - Google Patents

Abstract

PURPOSE: To obtain a nozzle which restrains oxygen from being dissociated in an aerial-current component at a nozzle exit part by a method wherein, when a gas, to be tested, which is composed mainly of nitrogen is passed through a nozzle throat, oxygen is jetted so as to be mixed. CONSTITUTION: A gas to be tested flows into from the direction of an arrow 7, and it is detected that the gas has reached the upstream part of a throat. Then, oxygen which has been pressurized is passed through a chamber 3, and it is jetted to the direction of an arrow 4 by a jet hole so as to be mixed with the gas, to be tested, at a downstream part from a boundary line 5. Since the oxygen is jetted on the upstream side of a sound-velocity line 6, a disturbance due to shock waves is small. Since the gas to be tested is constituted mainly of nitrogen, a mixed gas of the nitrogen and the oxygen is produced when the oxygen is jetted at the throat part, and the dummy air can be formed at this time. The sum of the mass fraction of the gas to be tested and that of the jetted oxygen is set at 100%. Then, a jet flow rate is adjusted in such a way that the mass fraction of the oxygen becomes 21%. When the nitrogen and the oxygen are mixed sufficiently at a proper mass fraction ratio at the throat part, the composition of every component at a nozzle exit part can be brought close to that of the air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle for a high temperature wind tunnel used in a ground wind tunnel facility for simulating an atmospheric reentry phenomenon of a space shuttle.

[0002]

2. Description of the Related Art Conventionally, no special means has been taken in a nozzle for a high temperature wind tunnel in order to suppress the dissociation of oxygen. That is, under the conventional operating conditions, the dissociation of oxygen was not a serious problem. However, it is necessary to take some improvement measures to realize the aerodynamic test under higher operating conditions.

[0003]

It is necessary to create a high enthalpy flow in a ground wind tunnel facility that simulates the atmospheric reentry phenomenon of a space shuttle. As a device for generating a high enthalpy flow, a wind tunnel mainly using arc heating or shock waves can be considered. Conventionally, in all the wind tunnels, since the working fluid, air, is heated to a high temperature (10000K), most of the oxygen molecules are dissociated. Furthermore, even if the oxygen is rapidly expanded through the ultrasonic nozzle, the dissociated oxygen cannot return to the original oxygen molecule by the time it reaches the nozzle outlet, and the mass fraction becomes 10%.
% Dissociated oxygen may be present. When extremely dissociated air is used as a test gas in an aerodynamic test, it is difficult to simulate the atmospheric reentry phenomenon of a space shuttle.

An object of the present invention is to provide a nozzle for a high temperature wind tunnel which can suppress the dissociation of oxygen in the air flow component at the nozzle outlet.

[0005]

In order to achieve the above object, the present invention does not utilize air as a nitrogen / oxygen mixed gas as a test gas in a high temperature wind tunnel, but uses nitrogen and oxygen separately. That is, when the test gas containing nitrogen as the main component passes through the nozzle throat, oxygen is injected and mixed.

[0006]

According to the technical means of the above construction, when it is detected that the test gas reaches the upstream side of the throat, oxygen is injected from the injection hole provided in the throat portion and mixed with the test gas. At this time, the injection hole is provided in the subsonic region in the throat portion. By injecting in the subsonic region, it is possible to reduce the occurrence of disturbance due to shock waves. Since the composition of the test gas is mainly composed of nitrogen, a mixed gas of nitrogen and oxygen is created by injecting oxygen at the throat,
It can be simulated air. At this time, when the sum of the mass fractions of the test gas and the injected oxygen is 100%, the injection flow rate is adjusted so that 21% is the oxygen mass fraction. The velocity of the test gas near the throat is 1000 to 2000.
It is very fast at m / s, but since the diameter of the throat part is as small as several tens of mm, it can be mixed relatively easily. Finally, the composition of air is approximated at the nozzle outlet. Although the temperature of the gas in the throat part is about several thousand K, the throat part is short and the flow velocity is very high, so that the injected oxygen flows out to the nozzle part before it is dissociated. In the nozzle, the gas expands rapidly and the temperature drops, so even if a small amount of dissociated oxygen is generated, the reaction proceeds in the direction of recombination and the dissociated atoms try to return to the molecule, so there is no problem. In addition, gaseous oxygen is usually used as the injected oxygen. When using room temperature oxygen,
A cooling effect can be expected near the thermally severe throat.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged view of the vicinity of the throat of the high temperature wind tunnel nozzle. Since it is an axisymmetric body, only the upper half is shown in the figure. Reference numeral 1 is a nozzle throat, and 2 is a supersonic nozzle.

According to the above structure, when it is detected that the test gas flows in the direction of the arrow 7 in the figure and reaches the upstream of the throat, the pressurized oxygen passes through the chamber 3 and the injection hole causes the arrow 4 to move. And is mixed with the test gas downstream from the boundary line 5. Since the injection is performed on the upstream side of the sonic velocity line 6, there is little disturbance due to the shock wave. Since the test gas is mainly composed of nitrogen, a mixed gas of nitrogen and oxygen can be created by blasting oxygen in the throat part, and can be made into simulated air. At this time, the sum of the mass fractions of the test gas and the injected oxygen is 1
When set to 00%, the injection flow rate is adjusted so that 21% is the oxygen mass fraction. When nitrogen / oxygen is sufficiently mixed at an appropriate mass fraction ratio in the throat, the composition of each component at the nozzle outlet can be made close to that of air. When gaseous oxygen at room temperature is used as the jet oxygen, a cooling effect can be expected in the vicinity of the throat, which is thermally severe.

Another embodiment of the present invention will be described with reference to FIG. The difference of this embodiment from the first embodiment is that the nozzle throat portion is provided with a plurality of holes. In this case, the same effect as that of the first embodiment can be obtained, and the effect of cooling the nozzle wall surface can be expected more than that of the first embodiment.

[0010]

According to the present invention, when the test gas containing nitrogen as a main component passes through the nozzle throat, oxygen is injected and mixed to form simulated air at the nozzle outlet, and the proportion of dissociated oxygen is generated. Can be greatly reduced to approach the composition of air.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a nozzle throat portion for a high temperature wind tunnel used in an embodiment of the present invention.

FIG. 2 is a sectional view of a nozzle throat portion showing another embodiment of the present invention.

[Explanation of symbols]

1 ... Nozzle throat, 2 ... Supersonic nozzle, 3 ... Chamber, 4 ... Oxygen injection direction, 5 ... Boundary line, 6 ... Sonic line, 7
… Inflow direction of test gas.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kuniyoshi Tsubouchi 502 Jinritsucho, Tsuchiura City, Ibaraki Prefecture

Claims (2)

[Claims] 1. A nozzle for a high temperature wind tunnel in which a test gas containing nitrogen as a main component is expanded and accelerated by a supersonic nozzle, and a nozzle throat portion is provided with a hole for injecting and mixing oxygen into the test gas. Characteristic high-temperature wind tunnel nozzle. 2. The nozzle for a high temperature wind tunnel according to claim 1, wherein the nozzle throat has a plurality of holes.