JPH08271373A - Structure for nozzle section in arc heating type wind tunnel - Google Patents

Abstract

PURPOSE: To provide a structure for a nozzle section in an arc heating type wind tunnel capable of obtaining a stable ultra-supersonic speed and a high enthalpy current. CONSTITUTION: A nozzle section 15 is provided with a throat section 19 having a constant passage cross sectional area, a passage expansion section 20 having the passage cross sectional area expanded toward the tip, and an arc discharge section 24 constituted of a cathode 16 installed on the upstream side of a passage and an anode 17 installed on its downstream side. The anode 17 is installed within the range of the throat section 19, and the passage expansion section 20 is formed with a nozzle 18 made of an insulating material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a nozzle section in an arc-heated wind tunnel that is suitable for hypersonic velocity and high enthalpy flow and is suitable for performing atmospheric entry simulations and space environment tests of space vehicles. It is about structure.

[0002]

2. Description of the Related Art Recently, as space development has become active,
There is a demand for performing atmospheric entry simulations and space environment tests for space shuttles, HOPEs, and other space shuttles, and for that purpose hypersonic and high enthalpy wind tunnels (for example, Mach number (ratio of air velocity and sound velocity) of 5 or more). An arc-heated wind tunnel is used as one of the above.

FIG. 3 is a diagram showing an example of an arc heating type wind tunnel. The arc heating type wind tunnel 1 includes a measurement unit 2, a nozzle unit 3 including an arc discharge unit 23, an air supply system 4, a power supply 5, an exhaust system 6,
The vacuum tank 7, the cooling water system 8, and the second throat section 9 are roughly configured. Here, the measurement unit 2 is for installing the model 10 to actually perform the measurement, and the nozzle unit 3 accelerates the high-enthalpy airflow created by the arc discharge unit 23 to hypersonic velocity, and For injecting, the air supply system 4 for supplying gas to the nozzle part 3, the power supply 5 for supplying voltage to the arc discharge part 23 to generate arc discharge, The exhaust system 6 is for evacuating the vacuum tank 7, the cooling water system 8 is for cooling each part of the apparatus, and the second throat part 9 is for converting the flow velocity of the airflow from hypersonic velocity to subsonic velocity. belongs to.

FIG. 2 shows the structure of the nozzle portion 3 including the arc discharge portion 23 which is the main portion of the arc heating type wind tunnel. The nozzle portion 3 is divided into a throat portion 11 having a constant flow passage cross-sectional area and a flow passage expanding portion 12 located downstream of the throat portion 11 and having a flow passage cross-sectional area increasing toward the tip. A cathode 13 made of tungsten is installed on the upstream side of the throat portion 11, and a cylindrical anode 14 made of copper is installed on the downstream side thereof.
The cathode 13 and the anode 14 are the arc discharge part 23.
Is composed. The anode 14 not only serves as an electrode, but also serves as a nozzle. The center hole 14a of the anode 14 has a constant inner diameter on the base end side 14b thereof, and thus the throat. The part 11 is formed, and the distal end side 14c is expanded in diameter toward the front end to form the flow path enlarged part 12.

[0005]

Therefore, the gas is introduced into the nozzle portion 3, and at the same time, the cathode 13 and the anode 14 are introduced.
When a voltage is applied between them to generate an arc discharge, a cylindrical electron and ion plasma, a so-called positive column P, is generated and the cathode 13 and the anode 14 are connected by the positive column P. However, at this time, in the conventional nozzle section 3, the anode 14 extends from the throat section 11 to the flow channel expanding section 12 as described above, and therefore the grounding position of the positive column P in the anode 14 is not stable. As shown, there are cases where the flow path expansion portion 12 of the anode 14 is grounded. In that case, the flow path expansion part 1 which becomes the acceleration region of the air flow
Since the air flow is decelerated by the heating in 2,
In some cases, there has been a problem that the Mach number of the air flow in the measuring section is reduced.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a structure of a nozzle portion in an arc heating type wind tunnel capable of obtaining stable hypersonic velocity and high enthalpy flow. To do.

[0007]

In order to achieve the above object, the structure of the nozzle portion in the arc heating type wind tunnel of the present invention has a throat portion having a constant flow passage cross-sectional area and a downstream side of the throat portion. And an arc discharge part consisting of a cathode installed on the upstream side of the flow path and an anode installed on the downstream side of the flow path. Then, a hypersonic air flow is generated by performing an arc discharge in this arc discharge part, and in the nozzle part in the arc heating type wind tunnel for injecting the air flow through the flow path in the measurement part, the arc discharge part The anode is installed so as to fit within the range of the throat portion, and at least the inner wall surface of the flow channel expansion portion is formed of an insulating material. Is shall.

[0008]

According to the structure of the nozzle portion in the arc heating type wind tunnel of the present invention, the anode of the arc discharge portion is installed so as to be within the range of the throat portion, and at least the inner wall surface of the flow passage expanding portion is made of an insulating material. Since it is made of a material, the positive column generated when an arc discharge is generated between the cathode and the anode is always grounded at the throat part and never grounded at the flow path expansion part. That is, the positive column exists only in the throat part.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a view showing the structure of a nozzle portion 15 in the arc heating type wind tunnel of the present embodiment, in which reference numeral 16 is a cathode, 17 is an anode, and 18 is a nozzle.

The nozzle portion 15 is provided with a throat portion 19 having a constant flow passage cross-sectional area, and a flow passage expanding portion 2 located downstream of the throat portion 19 and having a flow passage cross-sectional area increasing toward the tip.
It has an arc discharge part 24 for generating an arc discharge. Therefore, a tungsten cathode 16 having a sharp tip and held by a cathode holder 20 is installed on the upstream side of the throat portion 19, and a cylindrical nozzle 18 made of an insulating material such as ceramics is provided on the downstream side thereof. is set up. Further, the central hole 18a of the nozzle 18 constitutes the throat portion 19 when the proximal end side 18b has a constant inner diameter, and the distal end side 18c successively enlarges the diameter toward the distal end to constitute the flow passage enlarging portion 20. are doing.
Further, a cutout 18d is formed in the central hole 18a of the nozzle 18 at the base end side of the throat portion 19.

An annular anode 17 made of copper is fixed in a state of being embedded in the notch 18d of the nozzle 18. As a fixing method, a method of screwing the anode 17 to the nozzle 18 may be used, or the anode 1 may be previously formed when an insulating material such as ceramics is molded.
The method of incorporating 7 may be used. Also, the anode 17
The central hole 17a of the nozzle has a constant inner diameter,
5 constitutes a part of the throat portion 19 which is closest to the base end side. The cathode 16 and the anode 17 form an arc discharge unit 24.

According to the structure of the nozzle portion 15 of this embodiment,
Since the anode 17 of the arc discharge portion 24 exists within the range of the throat portion 19 having a constant flow passage cross-sectional area, and the flow passage enlarged portion 20 is composed of the nozzle 18 made of an insulating material, the cathode 16, The positive column P generated when an arc discharge is generated between the anodes 17 is always grounded at the throat portion 19 as shown in FIG. 1, and in the case of the conventional nozzle portion in which the anode also serves as a nozzle. As described above, the positive column P does not come into contact with the ground in the flow path expanding portion 20.

Therefore, the positive light column P is always connected to the throat section 1.
Since it exists only in No. 9, the sonic velocity surface is stable and the air flow is stable, and since the air flow is not heated in the flow path expanding section 20, the flow path expanding section that the conventional nozzle section has The problem that the air flow slows down can be solved. Therefore, the arc-heated wind tunnel having the structure of the nozzle portion 15 of the present embodiment should be suitable for the atmospheric rush simulation and the space environment test of the space shuttle which requires hypersonic velocity and high enthalpy flow. You can

In this embodiment, the whole nozzle 18 is made of ceramics as an integral type, but at least only the inner wall surface side which is in direct contact with the air flow is made of an insulating material, and the other portions are made of an arbitrary material. It may be a nozzle formed in. Insulating materials other than ceramics may be used.

[0015]

As described above in detail, according to the structure of the nozzle portion in the arc heating type wind tunnel of the present invention, the anode of the arc discharge portion is installed so as to be within the range of the throat portion, Since at least the inner wall surface of the expansion part is made of an insulating material, the positive column generated by arc discharge between the cathode and anode is always grounded at the throat part, and the anode constitutes the flow path expansion part. Unlike the case of the nozzle section, the positive column does not come into contact with the ground in the flow path expanding section. Therefore, since the positive column always exists only in the throat part, the sonic surface is stabilized, the air flow is stabilized, and the air flow is not heated in the flow path expansion part which is the acceleration region. It is possible to solve the problem of deceleration of the airflow that the part has. Therefore, the arc heating type wind tunnel having the structure of the nozzle portion of the present invention is hypersonic,
It can be made suitable for atmospheric entry simulations and space environment tests of space vehicles that require high enthalpy flow.

[Brief description of drawings]

FIG. 1 is a side sectional view of a nozzle portion in an arc heating type wind tunnel shown as an embodiment of the present invention.

FIG. 2 is a side sectional view showing an example of a nozzle portion in a conventional arc heating type wind tunnel.

FIG. 3 is a schematic diagram showing a configuration of a general arc heating type wind tunnel.

[Explanation of symbols]

 1 Arc heating type wind tunnel 15 Nozzle section 16 Cathode 17 Anode 18 Nozzle 19 Throat section 20 Flow path expansion section 24 Arc discharge section P Positive column

Claims (1)

[Claims] 1. A throat portion having a constant flow passage cross-sectional area, and a flow passage expansion portion which is located on the downstream side of the throat portion and whose flow passage cross-sectional area increases toward the tip. It has an arc discharge part consisting of a cathode installed on the upstream side and an anode installed on the downstream side, and a hypersonic airflow is generated by performing an arc discharge in this arc discharge part, and in the measurement part, In the nozzle part in the arc heating type wind tunnel for injecting the air flow through the flow path, the anode of the arc discharge part is installed so as to be within the range of the throat part, and the flow path expansion part is at least the inside thereof. A structure of a nozzle portion in an arc heating type wind tunnel, characterized in that the wall surface is formed of an insulating material.