JP3300730B2 - Flat nozzle for arc heating wind tunnel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat nozzle (flat contour nozzle) used in a flat specimen test of an arc heating wind tunnel, and more particularly to a flat nozzle having a boundary layer suction means on a wall surface thereof.

[0002]

2. Description of the Related Art An arc-heated wind tunnel is used for investigating (testing) an airflow environment applied to a body surface when a spacecraft or the like re-enters the atmosphere at a high speed, and particularly for investigating heat resistance and heat insulation.

FIG. 5 is a conventional schematic perspective view showing the main part of the conventional apparatus. The arc heater 01 using a direct current discharge contacts the air flow ejected through a flat nozzle 02 to the right side of the figure, and the lower part thereof contacts the air stream. A plate-shaped specimen 03 is attached along the airflow.

FIG. 6 is a perspective view of the flat nozzle 02 shown in FIG. 5 when viewed from the opposite direction. The jet of air current is performed from the nozzle throat 02a to the nozzle outlet 02b.

[0005] In Fig. 5 and Fig. 6, the flat nozzle 02 is shown as an example, but the nozzle shape differs depending on the purpose of the test. Basically, if it is desired to keep the pressure and heat load uniform in the direction of the jet flow, that is, in the axial direction, the nozzle cross section should be uniform (nozzle wall parallel), and the axis should be perpendicular to the axis (perpendicular to the axis). When it is desired to keep the pressure and heat load uniform, the nozzle may be formed in a conical shape in which the nozzle cross section changes uniformly and uniformly in the axial direction. Of course, those of these intermediate shapes are also used.

When the airflow flowing along the object is viewed slightly microscopically, not limited to the airflow in the nozzle, the airflow flowing in contact with the surface of the object is referred to as an adherent flow due to friction with the object or due to friction with the object. The airflow hardly moves due to the stopping force of the visual unevenness, and gradually increases according to the viscosity as the distance from the surface increases, and rapidly increases at a certain distance or more. An airflow layer on the object side of a line connecting the position of transition to the airflow speed in the flow direction is generally called a boundary layer. The thickness of the boundary layer changes depending on the viscosity of airflow, temperature, surface roughness of an object, and the like. When viewed from a cross section perpendicular to the air flow, the static pressure change of the air flow is not uniform inside and outside the boundary layer. Since the latest data is disturbed by the boundary layer, it is desired that the boundary layer be completely absent or a uniform thin layer when investigating pressure (static pressure) and heat load.

In other words, in the above example, the boundary layer is a stagnant layer in which heat has already been radiated, and can also be referred to as a heat insulating layer for preventing heat exchange between an air flow (heating gas flow) and an object (test specimen). It interferes with the heating efficiency of the object, and its thick presence forces a large amount of airflow.

[0008] In the flat specimen test of the arc heating wind tunnel, a flat contour nozzle (a flat contour nozzle) was used in order to minimize the air flow rate, make the wind tunnel scale realistic, and apply a more uniform heat and pressure load in the axial direction. The contour is a nozzle wall shape that becomes parallel as it progresses in the axial direction, and is indispensable for giving a uniform pressure and heat load distribution in the axial direction. Is
A flow (secondary flow) in the direction perpendicular to the axis is grown in the nozzle, and a boundary layer having a very non-uniform thickness is produced in the direction, and the heat load, which is a main parameter of the test, is made extremely non-uniform in the direction perpendicular to the axis. There is a problem to do.

In the conventional example shown in FIG. 6, in order to obtain a uniform heat load in the direction perpendicular to the axis, the pressure and the heat load distribution in the axial direction are sacrificed, and the nozzle wall has a conical (simple swivel) shape. As a result, there is no record of achieving ideal load uniformity in both directions. In addition, about these prior arts, for example, the literature "The 60-MW Shu
tle Interaction Heating
Facility "and the like.

[0010]

The flat nozzle for the conventional arc heating wind tunnel has the following problems to be solved.

That is, in the conventional flat nozzle, the uniformity of the heat and pressure distribution, which is the test condition, must be limited to one or the other. If uniform conditions in the direction perpendicular to the axis are required, the conical shape is required. When testing using a nozzle and requiring uniform conditions in the axial direction, the uniform conditions in the direction perpendicular to the axis are sacrificed using a contour-shaped nozzle, and real environment conditions cannot be simulated at once. There was a problem.

[0012] Therefore, the performance of the test specimen must be evaluated by adding analysis including many assumptions based on the test data in both directions, and the test condition and the number of times of test naturally become enormous. .

The present invention solves the above-mentioned problems, and forcibly (aggressively) makes a boundary layer formed by a contour-shaped nozzle and non-uniform in the axial direction to apply a uniform heat load in both axial directions. It is an object of the present invention to provide a flat nozzle for an arc heating wind tunnel capable of performing the above.

[0014]

According to the present invention, as a means for solving the above-mentioned problems, in a flat nozzle used for a flat-shaped specimen test of an arc heating wind tunnel, a boundary layer is sucked into a nozzle wall surface.
Multiple holes penetrated by dividing the area into blocks and in front of the holes
Back pressure control valve connected to each block
A gas suction means communicating with the control valve and capable of reducing the pressure in the nozzle; and a gas suction means attached to the nozzle wall near the plurality of holes.
The holes divided into blocks were measured for uneven heat load distribution.
Controlling the back pressure control valve of the gas suction means corresponding to
To provide a flat nozzle for an arc heating wind tunnel, comprising: a plurality of heat load sensors .

[0015]

The present invention is configured as described above and has the following effects.

That is, a plurality of through-holes are provided in the wall surface of the flat nozzle, and a gas suction means provided with a back pressure control valve communicating with the holes and a heat load sensor are provided. For example, the boundary layer formed along the wall surface in the flat nozzle is sucked to the outside to solve the problem, or the control is performed so that the hole corresponding to the thick portion of the boundary layer among the plurality of holes is more strongly sucked. Thereby, the thickness can be made uniform.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a schematic configuration diagram showing a state in which a plate-shaped specimen test is performed using a flat nozzle (hereinafter simply referred to as a “nozzle”) in an arc heating wind tunnel according to this embodiment. a) is a side cross-sectional view, (b) is a cross-sectional view taken along the line AA of (a), FIG. 2 is an enlarged view (explanatory view) in the vicinity of the boundary layer suction hole 2 of FIG. 1 (a), and FIG. 1 (a), a schematic diagram for comparing a plurality of circular cases and a slot-like case when the boundary layer suction holes 2 are viewed in the hole axis direction, and FIG. 4 is a comparative performance line of the test results. FIG.

In FIG. 1, reference numeral 1 denotes a nozzle shown in a side sectional view,
1a is a nozzle throat, 1b is a nozzle outlet, 1c is a nozzle wall, 2 is a plurality of boundary layer suction holes penetrated through the lower nozzle wall 1c of the nozzle 1, 3 is a boundary layer suction hole 2, and a width direction of the airflow. A suitable number of the nozzles 1 communicate with each other via a pipe line to suck the gas in the nozzle 1, thereby sucking the boundary layer formed near the nozzle wall 1 c surface, that is,
A back pressure control valve for controlling the back pressure, 4 is a heat load sensor (calorimeter) for measuring the heat load distribution on the nozzle wall 1c surface, 5 is a gas sucked by the vacuum pump 6 via the boundary layer suction hole 2 When the temperature is relatively high, a heat exchanger for cooling the suction gas from the viewpoint of protection of the vacuum exhaust pump 6, etc., and a vacuum 6 for continuously sucking the gas in the nozzle 1 from the boundary layer suction hole 2 It is an exhaust pump.

Next, the operation of the above configuration will be described.

First, an outline of the operation will be described. The lower wall surface of the contour-shaped flat nozzle 1, that is, the nozzle wall 1c (specimen 0
3), the boundary layer suction hole 2 is provided, so that if the back pressure is set lower than the nozzle air flow static pressure by the vacuum exhaust pump 6 and the back pressure control valve 3, the boundary layer suction hole 2 Is sucked from the boundary layer suction hole 2, the temperature boundary layer becomes thinner, the gas temperature gradient near the nozzle wall 1c can be made larger, and the nozzle determined by (gas temperature gradient) × (transfer coefficient) The heat load on the wall 1c can be increased.

That is, as shown in FIG. 2, a thicker temperature boundary layer is made thinner by forming a boundary layer and positively sucking a cooled gas while applying heat to the nozzle wall 1c by a differential pressure. By changing the temperature gradient in the vicinity of the nozzle wall 1c surface, it is possible to increase the heat load on the test pieces 03 set flush.

Next, the operation will be described in detail.

The boundary layer suction hole 2 is divided into blocks on the lower wall surface of a wide area downstream of the nozzle 1, that is, the nozzle wall 1c, and the boundary layer suction area is subdivided to provide a more uniform heat load and a higher heat load. It is arranged so that it can be given. Further, a plurality of thermal load sensors 4 (one in the width direction of the airflow, many) are attached, so that unevenness of the thermal load distribution caused by unevenness of the boundary layer thickness can be accurately measured. From the measured values, an appropriate boundary layer suction amount is estimated, the back pressure of each corresponding boundary layer suction hole 2 is set to a target value by the back pressure control valve 3, and gas in the boundary layer is sucked,
That is, the heat load is controlled. The suction can be performed continuously and stably by the vacuum pump 6. If the temperature of the suction gas is relatively high, the heat exchanger 5 is operated to lower the temperature of the suction gas.

As shown in FIG. 3, a suction plate 1d having boundary layer suction holes 2a and 2b (slot-like) simulating a nozzle wall in order to confirm a change in heat load due to suction of the boundary layer (feasibility of the present method). , 1e were replaced and installed at the nozzle outlet 1b, and as a result of the investigation, the difference between the static air pressure and the back pressure was 10 Torr.
Although smaller than r, as shown in FIG. 4, a heat load improvement (control) of 1.6 to 2.8 times was confirmed as compared with the case without the suction hole (that is, the conventional example).

As described above, according to this embodiment, the nozzle 1
A plurality of boundary layer suction holes 2 penetrating through the lower nozzle wall 1c downstream of the nozzle wall 1c appropriately aspirate the boundary layer in the vicinity of the nozzle wall 1c and aspirate the same, so that the thickness thereof can be made uniform. There is an advantage that the heat load received can be improved by 1.6 to 2.8 times as compared with the conventional example.

If the test is performed without using the vacuum pump 6 (or by closing the back pressure control valve 3), there is an advantage that the nozzle 1 can be used as a conventional contour-shaped nozzle.

Further, by distributing a large number of boundary layer suction holes 2 over a wide area and connecting suction lines independently of each other, the boundary layer in the width direction of the gas flow (gas flow) can be freely controlled. There is the advantage that the data of many cases can be obtained correspondingly and the test range is significantly expanded.

Further, since the boundary layer can be controlled to be thin, the heating (heating) efficiency for the specimen is increased, and there is an advantage that the air flow required for the test can be correspondingly reduced.

Further, since the thickness of the boundary layer can be controlled uniformly, there is an advantage that accurate test data can be obtained. Therefore, there is an advantage that a large number of tests are not required and the test period is shortened.

[0031]

The present invention has the following effects because it is configured as described above.

That is, a gas suction means , a heat load sensor, which penetrates a plurality of holes through a nozzle wall surface of a flat nozzle used for a flat-shaped specimen test of an arc heating wind tunnel and has a back pressure control valve capable of reducing the pressure in the nozzle. Is provided, the gas suction means is operated to suck the boundary layer in the nozzle wall surface, and the boundary layer can be eliminated or controlled to have a uniform thickness, so that the heat load efficiency for the specimen can be remarkably improved.

Further, since the boundary layer can be controlled to be thin and uniform in thickness, accurate test data can be obtained.

Further, since the heat load efficiency for the specimen can be remarkably improved, the air flow rate can be significantly reduced. Accordingly, heat source power, test time, and the like are also reduced.

Further, since the thickness of the boundary layer can be variously changed, the test range is greatly expanded.

In addition, since accurate test data can be obtained, the number of tests and, therefore, the test period can be shortened.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a state in which a flat nozzle test is performed using a flat nozzle in an arc heating wind tunnel according to an embodiment of the present invention, (a) is a side sectional view, and (b) is a side view. Is a cross-sectional view taken along the line AA in FIG.

FIG. 2 is an enlarged view (explanatory view) of the vicinity of a boundary layer suction hole 2 in FIG.

FIG. 3 is a schematic explanatory view showing a comparative test situation using suction plates 1d and 1e having boundary layer suction holes 2a and 2b (slot shape) corresponding to FIG. 1 (a);

4 is a comparative performance diagram showing test results in FIG. 3,

FIG. 5 is a schematic perspective view showing a test situation using a conventional arc heating wind tunnel;

FIG. 6 is a perspective view of the flat nozzle 02 in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle (flat nozzle) 1c Nozzle wall 2 Boundary layer suction hole 3 Back pressure control valve 4 Heat load sensor (calorie meter) 5 Heat exchanger 6 Vacuum exhaust pump 03 Specimen

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01M 9/04

Claims (1)

(57) [Claims] In a flat nozzle used for a flat-shaped specimen test of an arc heating wind tunnel , suction of a boundary layer on a nozzle wall surface is performed.
A plurality of holes through the viewing range and divided into blocks, the same hole
A back pressure control valve connected to each of the blocks;
A gas suction means communicating with the pressure control valve and provided so as to reduce the pressure in the nozzle, and attached to the nozzle wall near the plurality of holes;
The unevenness of the heat load distribution was measured and divided into blocks.
Controlling the back pressure control valve of the gas suction means corresponding to the hole
A flat nozzle for an arc-heating wind tunnel, comprising: a plurality of heat load sensors .