JPH07286936A - Airflow heater for wind tunnel - Google Patents

Abstract

PURPOSE:To enable clean flow with no debris mixed in the airflow to be formed by forming an airflow-heating heat reservoir body of a plurality of porous plates perforated for the passage of the airflow. CONSTITUTION:Each porous plate 3 of a heat storage body, through which a number of small-diameter holes 31 are formed to allow passage of airflow 4, is set perpendicular to the axis of a heater 2 and fitted into a groove 25, and a lid 27 is closed to heat the porous plates using a heating unit 26. Next, high-pressure airflow 4 from a bladder is introduced into a heater 2 from an inlet 21, and the airflow 4 introduced is allowed to pass through the holes 31 of the numerous porous plates 3 spaced apart inside the heater 2, and is converted into high-temperature airflow 5. In this case, the diameter and number of the holes 31, and the number of the porous plates 3, are adjusted to heat the passing airflow to a preset stagnation point, and the area of heat transfer is increased to reduce the time required for the airflow 4 to become the high-temperature airflow 5 at a predetermined temperature. Also, the porous plates 3 can be replaced easily using a crane with the lid 27 open. Therefore, the porous plates 3 are not moved, damaged and pulverized by the action of the high-pressure airflow 4, and the clean airflow with no debris mixed therein can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in a wind tunnel such as a hypersonic wind tunnel in which a gas in a high temperature state is aerated, and prevents dust generated from a heater when heating the aerated gas,
The present invention relates to an air flow heater for a wind tunnel that can perform a wind tunnel test with a clean air flow.

[0002]

2. Description of the Related Art In a hypersonic wind tunnel or the like, a high temperature and high pressure gas obtained by using an air flow heater for a wind tunnel is used as a stagnation state of the wind tunnel, and is passed through a hypersonic nozzle to a measuring section. There is one that is designed to obtain the required hypersonic Mach number. In such a wind tunnel, a hypersonic flow of about 1 to 2 minutes can be obtained at the measurement unit, and the state of the stagnation point of the wind tunnel can be changed over a wide range. Widely used in development.

Such a conventional hypersonic wind tunnel device and its operating condition will be described with reference to FIG. In the figure, 01 is a heater, which is composed of a cylindrical container,
A large number of alumina pebbles 02 as a heat storage body for heating a gas (hereinafter, referred to as an air flow) ventilated in the wind tunnel are stored.
Further, the heater 01 is equipped with a gas burner 03 as a heating device for heating the alumina pebble 02. After heating the alumina pable 02 with the gas burner 03 for several hours, the gas from the gas storage tank 04 is removed. A high-pressure air flow is introduced into the heater 01 from the inflow port 05, and is passed between the transferred alumina pebble (alumina pebble layer), so that the introduced high-pressure air flow is discharged as a high-temperature high-pressure air flow. It discharges from 06 to the collecting cylinder 07. The airflow in the stagnation point state of high temperature and high pressure in the collecting cylinder 07 is isentropically expanded by the nozzle 08, and a hypersonic flow with an airflow Mach number of 5 or more is generated in the measurement unit 09 at low temperature. A wind tunnel model 010 is installed in the measurement unit 09, and here, the wind tunnel model 010 is installed.
Measures the aerodynamic force and aerodynamic heating that acts on.

Further, in 011, the temperature of the air flow passing through the measuring section 09 at hypersonic speed increases again due to deceleration,
This is a cooler that cools this. Further, 012 is a muffling tower that reduces the noise generated by the operation of the wind tunnel to a required level, and 013 is a vacuum chamber as a large suction facility for effectively creating a hypersonic air flow.

In such a conventional hypersonic wind tunnel, the heating medium for heating the air flow, that is, the heat storage body 02 for heating by contact with the air flow is a pebbles of alumina pebble (aluminum oxide (Al ₂ O ₃ )). ) Layer,
When a high-pressure airflow flows into the heater 02 at a high speed and passes through the alumina pebble layer, the alumina pebbles move and rub against each other due to the airflow, or the side walls of the heater 01 collide with each other and are damaged, resulting in minute damage. Generates powder. Then, this fine powder flows out of the heater 01 together with the air flow, becomes debris, and is a wind tunnel facility including a valve body of a shut-off valve (not shown) installed in the discharge pipe line downstream of the heater 01. , And cause damage to the wind tunnel model 010. In particular, in the measurement unit 09, since the air flow becomes high speed, debris directly collides with the wind tunnel model 010 set in the measurement unit 09, and there is a disadvantage that fine erosion occurs on the wind tunnel model 010 surface. It becomes remarkable. That is, in the aerodynamic force measurement test of the wind tunnel model 010, as the wind tunnel test progresses, the surface of the wind tunnel model 010 becomes rough, causing a slight disturbance in the air flow on the surface of the wind tunnel model 010, and lowering the accuracy of the aerodynamic force measurement data. In the aerodynamic heating measurement, there is a problem that the measurement data of the aerodynamic heating is affected by the collision of debris on the heat sensor on the surface of the wind tunnel model 010, and the accuracy of the measurement data is reduced.

FIG. 6 is a diagram comparing an aerodynamic force measurement value and an aerodynamic heating measurement value with an air flow D containing debris and a clean air flow C containing no debris. As shown in FIG. 6 (A), the increase in the lift coefficient C _L with the increase in the angle of attack α is larger in the measured value in the airflow D including debris than in the clean airflow C. % Goes up. Also,
As shown in FIG. 6B, in the aerodynamic heating measurement of the leading edge of the main wing, the aerodynamic heating rate at the leading edge of the main wing, the measured value in the air flow D containing debris, and the measured value in the clean air flow C are shown. It is about 10% higher than in this way,
It can be seen that the air flow D containing debris has a significant effect on the accuracy of the measurement data due to the debris contained in the air flow.

On the other hand, by using a heat-defective conductor called alumina pebble 02 for the heat storage body, the heat storage effect is high,
While the heating time of the high-pressure airflow passing through the alumina pebble layer is long, the heating to the passing airflow becomes slow, and as a result, the temperature in the collecting cylinder 07 reaches a required level and is relatively low until it cools down. There is a problem that requires a long time. That is, until the high-speed airflow in the measurement unit 09 becomes stable, the aerodynamic force applied to the wind tunnel model 010 or the aerodynamic heating measurement cannot be performed, and during that time, the air-blowing only to generate the hypersonic flow in the measurement unit can be continued. Inevitably, there was waste associated with this.

Further, since the alumina pebbles having a poor thermal conductivity are used as a heat storage material, the temperature of the alumina pebbles layer in a portion where a large amount of high-speed air current flows greatly decreases, and the temperature in a portion where the air current does not flow at all is large. Since the decrease is small, there is a problem due to an imbalance in the temperature distribution of the alumina pebble layer. That is, from the viewpoint of heat resistance, alumina pebble,
The heating by the gas burner 03 can be performed only after the temperature distribution of the entire alumina pebbles is approximately in equilibrium, so that the heating of the heat storage body for the next wind tunnel test after the completion of one wind tunnel test causes a temperature drop. It is necessary to wait for cooling of the alumina pebble layer in a portion where there is little heat before heating, which takes time, and there is also the problem that the wind tunnel operating rate significantly decreases.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art. (1) When a high-speed air flow passes, debris of fine powder does not occur, and damage to the wind tunnel model or the like due to debris occurs. It is possible to improve the accuracy of measurement data without causing it. (2) The heating of the passing airflow is performed rapidly, which promotes the stability of the airflow, and the imbalance of the temperature distribution in the heat storage body that occurs during wind tunnel operation. However, it is an object of the present invention to provide an airflow heater for a wind tunnel that can be promptly resolved after the wind tunnel is stopped and the use efficiency and operating rate of the wind tunnel can be improved.

[0010]

Therefore, the airflow heater for a wind tunnel according to the present invention has the following means.

A heat storage body, which is installed in a heater and heats a gas (air flow) that is ventilated in a wind tunnel by contact, is formed of a plurality of perforated plates having a large number of holes through which the air flow passes.

The porous plate is arranged substantially orthogonal to the axis of the cylindrical heater, and the porous plate is arranged inside the heater with a gap between adjacent porous plates. It was fixed to the heater so as not to move.

[0013]

The airflow heater for a wind tunnel of the present invention has the following means. (1) The movement of the perforated plates constituting the heat storage body due to the airflow passing through the heat storage body is eliminated, the mutual rubbing of the perforated plates or the inner wall of the heater Can be prevented, the generation of fine powder can be prevented, the wind tunnel model can be prevented from being damaged, and the accuracy of the wind tunnel test measurement data can be improved. Further, it is possible to prevent damage to the wind tunnel equipment installed on the downstream side of the heater. (2) Since the perforated plates constituting the heat storage body are arranged in the direction orthogonal to the axis of the heater, and a gap is provided between the adjacent perforated plates, it is possible to form an air flow in the heater in the axial direction. The heat exchange is promptly performed, a stable airflow under a constant temperature condition is obtained in a short time, and useless operation of the wind tunnel can be reduced. (3) Further, since the airflow passing through the heat storage body flows evenly through the plurality of perforated plates, there is little imbalance in the temperature distribution of the perforated plates after the end of the operation of the wind tunnel, and the temperature distribution of the perforated plates becomes substantially uniform in a short time. Reheating can be started in a short time, and the operating rate of the wind tunnel can be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the airflow heater for a wind tunnel according to the present invention will be described below with reference to the drawings. FIG. 1 is a view showing a first embodiment of an air flow heater for a wind tunnel of the present invention, and FIG. 1 (A) is a vertical sectional view,
FIG. 1 (B) is a front view of a perforated plate constituting the heat storage body, FIG.
(C) is a perspective view showing the inside.

As shown in these figures, the airflow heater 1 for a wind tunnel comprises a heater 2 and a perforated plate 3 as a heat storage body.
The heater 2 has a cylindrical shape with an inlet 21 for introducing the high-pressure airflow 4 from the air storage tank into the inside of the heater 2 and an outlet 22 for discharging the hot airflow 5 heated inside to the downstream side. And a vacuum layer 23 for suppressing heat conduction and radiation to the surroundings. In addition, the porous plate 3 is provided inside the vacuum layer 23 of the cylindrical portion 24.
An electric heater 26 is provided as a heating device, which has a groove 25 for fitting the peripheral edge of the perforated plate 3 formed orthogonally to the axis of No. 4 and serving as a heating device. Further, the cylindrical portion 24 of the heater 2 has a vertically divided structure, and the upper portion has a lid 27 structure capable of opening and closing the inside.

The porous plate 3 is made of a refractory metal such as tungsten, molybdenum, tantalum, etc., having a disk-shaped outer shape,
It has an aperture ratio of 30 to 60% in which a large number of small holes 31 through which the air flow 4 passes are opened.

After the lid 27 of the heater 2 is opened and the perforated plate 3 hung by a crane is fitted into the groove 25 formed on the inner surface of the heater 2 so as to be orthogonal to the axis of the heater 2, Lid 27
And the perforated plate 3 is heated by the electric heater 26. In the case of this embodiment, the perforated plate 3 can be heated up to the 1000 ° C. level in a few minutes. Then, a high pressure air flow 4 from the air storage tank is operated from a valve provided in the pipe line to heat the heated air 2 from the inflow port 21.
To be introduced inside. High-pressure airflow 4 introduced into heated air 2
Becomes a high-temperature airflow 5 by passing through the holes 31 of a large number of perforated plates 3 arranged in the heater 2 at intervals.
By adjusting the diameter of the holes 31 of the perforated plate 3, the number of the holes 31 and the number of the perforated plates 3, the passing airflow can be heated to the temperature of the set stagnation point. The perforated plate 3 can also be easily replaced by opening the lid 27 above the heater 2 and raising and lowering one by one with a crane. Further, since the perforated plate 3 is made of a metal having a high melting point, and the heat transfer area can be increased depending on the number of the small holes 31 formed in the perforated plate 3 and the number of the perforated plates 3, the heating efficiency of the air flow 4 is increased by the alumina pebble. By adjusting the power level of the electric heater 26 so that the temperature of the high temperature airflow 5 becomes substantially constant and the time for the airflow 4 to reach the high temperature airflow 5 of a predetermined temperature is faster. You can control.

Since this embodiment is constructed as described above,
When heating the air flow 4, the porous plate 3 as a heat storage body moves and is damaged by the action of the air flow 4 passing through the heater 3.
It is possible to form a clean hypersonic flow without debris in the measurement section without generating fine powder. This will not cause erosion on the surface of the wind tunnel model, and
The accuracy of the measurement data of the wind tunnel model can be improved. Further, damage to the wind tunnel equipment including the valve body of the shutoff valve installed on the downstream side of the heater 2 will not occur.

Further, since the heating efficiency is improved, a stable air flow having a predetermined temperature can be obtained in a short time, so that the air blowing time of the wind tunnel can be reduced and an efficient wind tunnel test can be carried out.

Further, when the wind tunnel test of one form is completed and the wind tunnel is stopped, the temperature distribution of the perforated plate 3 has a small imbalance and the temperature distribution becomes substantially uniform in a short time. The reheating of the perforated plate 3 for the test can be performed within a short time, and the wind tunnel stop time can be shortened to increase the wind tunnel operating rate.

Next, FIG. 2 is a vertical sectional view showing a second embodiment of the present invention. In this embodiment, the inside of the vacuum layer 23 provided in the cylindrical portion 24 of the heater 2 is covered with a cylindrical heat insulating material 28.
And is provided with a burner 29 as a heating device. In the case of this embodiment, as compared with the first embodiment, the groove 26 formed on the inner surface of the heat insulating material 28 on which the perforated plate 3 is disposed becomes easier to process, but the time required for heating the perforated plate 3 is longer. Become. However, the perforated plate 3 can be heated to the 1000 ° C. level in about 30 minutes, and the heat exchange can be made higher than that of the conventional one. The operation and effect of this embodiment are the same as those of the first embodiment except for the above points.

Next, FIG. 3 is a view showing a third embodiment of the present invention, FIG. 3 (A) is a longitudinal sectional view, and FIG. 3 (B) is a front view of a perforated plate. In this embodiment, the heater 2 is arranged vertically as in the conventional case. The perforated plate 3'is made of alumina. The perforated plate 3'is provided by penetrating the columns 32, and the upper and lower ends of the columns 32 are fixed to the inside of the heater 2 and the inside of the heater 2. The perforated plates 3'are horizontally stacked and supported.

In this embodiment, the groove on the inner surface of the cylindrical heat insulating material 28 is not required, and the processing is further facilitated.
Since the perforated plate 3'is assembled outside the heater 2 and can be installed inside the heater 2 as an aggregate, and can be taken out from the inside of the heater 2 as an aggregate, the perforated plate 3 '
It will be extremely easy to perform maintenance and inspection. Further, the perforated plate 3'of the present embodiment is formed of an alumina (Al ₂ O ₃ ) plate as described above, but has a structure in which it is firmly held at equal intervals by the five columns 32. The perforated plate 3 ′ does not move due to the high-speed air flow, and the perforated plates 3 ′ do not come into contact with each other or between the perforated plate 3 ′ and the inner wall of the heater 2 such as the heat insulating material 28, so that generation of fine powder can be prevented.

Also, the heating time by the burner 29 is faster than the heating of the conventional tightly packed alumina pebbles, the heat is transferred to the entire inside of the heater 2 through the holes of the perforated plate, and one hour is sufficient. . The heating efficiency is not much different from the case of alumina pebble, but the appropriate temperature setting can be done in a short time by adjusting the heat transfer area by the number of perforated plates 31, the diameter and number of holes 31, and the set temperature by the burner. Can be done at. The heater 2 is of a vertical type as described above, and in this case, the lid 27 'on the upper side is opened and the heater 2 is taken out by a crane. In addition, the first embodiment and the second
Compared with the embodiment, it can be made lighter in weight and more advantageous in price.

Next, FIG. 4 is a view showing a fourth embodiment of the present invention. FIG. 4 (A) is a longitudinal sectional view, FIG. 4 (B) is a front view of a perforated plate 3 ″, and FIG. 4 (C). FIG. 4 is a partial vertical cross-sectional view of a porous plate 3 ″.

This embodiment has substantially the same structure as that of the third embodiment, except that the porous plate 3 "is made of an alumina porous plate 35 and a refractory metal 34.
It is completely wrapped and formed. Therefore, the air flow 4 passing through the heater 2 exchanges heat with the refractory metal 34 parts, and the heating efficiency is improved as compared with the third embodiment, and the strength becomes rigid, and the generation of fine powder is completed. Can be prevented. Further, by adopting the alumina porous plate 35, there is also a heat storage effect, and while the heating time of the airflow 4 passing therethrough can be lengthened, the porous plate 3 ″
Since the heat transfer area can be freely set according to the number of holes, the number of holes 31, the diameter, and the number, the rapid heat transfer characteristic to the air flow 4 is not lost.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that combinations of the above-mentioned embodiments are possible without departing from the scope of the claims. It includes.

[0028]

According to the airflow heater for a wind tunnel of the present invention, with the structure shown in the claims, generation of fine powder, that is, debris, from the heat storage medium, which is the heating medium, is suppressed, and debris is generated in the airflow. It is possible to realize a clean flow without any increase, and to improve the measurement accuracy of aerodynamic and aerodynamic heating.
Also, by improving the air heating efficiency, the airflow temperature can be stabilized quickly and the same test data can be acquired.
It requires less ventilation time. Further, the heating time of the heater is greatly shortened, and the heat storage body can be reheated after the wind tunnel is stopped within a short time, which leads to a dramatic improvement in the wind tunnel operating rate. As a result, the development of hypersonic airplanes and spacecraft can be dramatically accelerated.

[Brief description of drawings]

FIG. 1 is a view showing a first embodiment of an air flow heater for a wind tunnel of the present invention, FIG. 1 (A) is a vertical sectional view, FIG. 1 (B) is a front view of a perforated plate, and FIG. 1 (C) is Perspective view,

FIG. 2 is a vertical sectional view showing a second embodiment of the present invention,

FIG. 3 is a view showing a third embodiment of the present invention, FIG. 3 (A) is a longitudinal sectional view, FIG. 3 (B) is a front view of a perforated plate,

FIG. 4 is a view showing a fourth embodiment of the present invention, FIG. 4 (A) is a vertical sectional view, FIG. 4 (B) is a front view of a perforated plate, and FIG. 4 (C) is a partial sectional view of the perforated plate. ,

[Fig. 5] Overall device diagram of the hypersonic wind tunnel,

FIG. 6 is a comparison diagram of measurement data according to the state of air flow.
(A) is a comparison diagram of aerodynamic measurement data, FIG. 6 (B) is a comparison diagram of aerodynamic heating measurement data,

[Explanation of symbols]

 1 Wind Tunnel Air Flow Heater 2 Heater 3, 3 ', 3 "Perforated Plate 4 Heated Air Flow 5 High Temperature Air Flow 21 Inlet 22 Discharge Port 23 Vacuum Layer 24 Inner Cylinder Part 25 Groove 26 Electric Heater 27, 27 as Heating Device ′ Lid 28 Insulating material 29 Burner as a heating device 31 Hole 32 Strut 34 High melting point metal for coating 35 Alumina plate

Claims (1)

[Claims] 1. A tubular body provided with a heat storage body for heating by performing heat exchange by contacting with the air flow, an inlet for introducing and discharging the air flow, a discharge port, and a heating device for heating the heat storage body housed inside. In the air current heater for a wind tunnel, which comprises the heater, the plurality of perforated plates arranged and fixed in the inside of the heater, the heat storage bodies being substantially orthogonal to the axis of the heater and having a mutual interval therebetween. An air flow heater for a wind tunnel, which is characterized by