JP2515649B2 - Pressure control device for blow-out wind tunnel - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is generally used when performing a high Mach number aerodynamic test such as in a hypersonic wind tunnel. More specifically, the temperature of air decreases as it accelerates and liquefies. The present invention relates to a pressure control device for a blow-out type wind tunnel provided with a heater for preventing the above.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing a general structure of a blow-out type wind tunnel of this type. In FIG. 4, 1 is an air storage tank for storing high-pressure compressed air. Reference numeral 3 denotes a pressure regulating valve, which guides the high-pressure compressed air in the air storage tank 1 through the high-pressure conduit 2 and reduces the pressure to a constant pressure according to the valve opening adjusted by a signal from the outside. Reference numeral 4 is a heater, 5 is a collecting cylinder, 6 is a nozzle, and 7 is a measuring unit. The compressed air depressurized to a constant pressure by the pressure regulating valve 3 is used as the heater 4, the collecting cylinder 5, the nozzle 6 and the measuring unit. It is discharged into the vacuum chamber 8 via the section 7. Here, a is a shutoff valve for shutting off the outlet of the heater 4, and b is a cooler for cooling the air that has exited the measuring unit 7. Further, air heating by the heater 4 is usually 800 ° C to 1 ° C.
At about 000 ° C., the air is prevented from being liquefied due to the decrease of the air temperature accompanying the acceleration.

In the above-mentioned wind tunnel, since only the compressed air stored in the air storage tank 1 allows ventilation and all the air after ventilation is discharged into the vacuum chamber 8, the ventilation time is typically several seconds. It is limited to a very short time of about several tens of seconds, during which all measurements must be completed.
Further, after the compressed air inside the air storage tank 1 is released by ventilation to increase the pressure in the vacuum tank 8, the air storage tank 1 is refilled for a retest and the vacuum tank 8 is again filled with a predetermined vacuum. Requires a large amount of time on the order of several hours. Further, in the wind tunnel for performing the aerodynamic test at such a high Mach number, since the Mach number of the airflow is determined by the shape of the nozzle 6, no special control device is provided, and the nozzle is not provided in accordance with the required Mach number. It is customary to replace 6.

[0004] The pressure control device in the wind tunnel controls the total pressure of the collecting cylinder 5, that is, the stagnation point pressure to a predetermined value.
It has the function of adjusting the opening of the pressure regulating valve 3, and in order to stabilize the air flow inside the wind tunnel in a short time in order to extend the test time even a little, in addition to the accuracy to guarantee the reproducibility of the test. High-speed response is required.

By the way, a conventional pressure control device for a blow-out type wind tunnel is constructed as shown in FIG. In the figure, reference numeral 10 is a pressure control device, and the opening of the pressure setting device 11, the feedback control unit 12 for performing proportional / integral control, and the ventilation valve 3 does not become excessive at the beginning of ventilation, and the air flow rate of the heater 4 does not become excessive. As described above, the valve opening limiter 13 keeps the opening of the pressure regulating valve 3 at a constant opening. In the conventional blow-out type wind tunnel pressure control device having such a configuration, the pressure on the downstream side of the pressure regulating valve 3 is detected by the pressure transmitter 9 as the stagnation pressure of the collecting cylinder 5, and the detection signal and the pressure setting device 11 are used. The feedback control unit 12 calculates a deviation from the pressure setting signal output from the feedback control unit 12 and performs proportional / integral calculation on the deviation. Aerospace technology research institute report TR-116, TR
-647, JP-A 61-138304, JP-A 63-
235845, JP-A-63-256835 and JP-A-2-302642).

Further, in order to prevent an increase in the air flow rate to the heater 4 in the initial stage of ventilation, ventilation is started with the shut-off valve a closed, and the feedback control unit is provided after the heater 4 is completely filled with air. Activating 12 was also done.

[0007]

By the way, the heater 4 of the wind tunnel of this kind generally has a large amount of heat storage body (usually about 7 to 10 tons) therein, and an excessive air flow rate is applied to this. If it is given, the heat storage body may float up and damage the inside of the heater 4, which may cause the following control problem. That is, it is necessary to limit the air flow rate in order to prevent the heat storage body inside the heater 4 from floating, but in the conventional device, safety is confirmed empirically because there is no mechanism for limiting the air flow rate. I have no choice but to drive within the range.

Further, in the case of a new facility, it is necessary to determine the operable range by trial and error, the trial operation period becomes long, and there is a high possibility that the heater 4 is damaged by an erroneous operation. Further, when adjusting the pressure control device, it is necessary to consider the floating of the heat storage body inside the heater 4, and it is difficult to select control parameters until sufficient pressure control performance is exhibited.

The present invention has been made in view of the above situation, regardless of the setting of the operating point in the early stage of ventilation,
The floating heat storage inside the heater is eliminated, and even if there is an error in the trial run, the heater is prevented from being damaged,
It is an object of the present invention to provide a pressure control device for a blow-out type wind tunnel that can realize safe and high-performance pressure control.

[0010]

In order to achieve the above object, a pressure control device for a blow-out type wind tunnel according to claim 1 of the present invention is a differential pressure limit setting device for setting a pressure difference allowed by a heat storage type heater. The differential pressure limit setting signal output from the heater and the differential pressure signal of the heater output from the differential pressure signal transmitter that detects the pressure difference between the inlet and the outlet of the heater are input to the differential pressure limit control unit for heating. When the differential pressure limit signal exceeds the differential pressure limit setting signal, a differential pressure limit control unit that outputs a differential pressure limit control signal for limiting the air flow rate, a pressure control signal output from the pressure control unit, and the difference The differential pressure limiting control signal output from the pressure limiting control unit is input, and a low level signal selector that outputs a signal corresponding to the one with a smaller air flow rate is provided.

According to a second aspect of the present invention, there is provided a pressure control device for a blow-out type wind tunnel, wherein the differential pressure signal transmitter is a first pressure transmitter for detecting pressure on the inlet side of the heater, and the heater. A second pressure transmitter for detecting the pressure on the outlet side of the device and a subtractor for calculating the difference between the pressures detected by the first and second pressure transmitters are used. is there.

[0012]

According to the first aspect of the present invention, in the pressure control section, the air flow rate necessary for maintaining the pressure of the collecting cylinder at the set value is set by the well-known control means such as normal feedback control and feedforward control. The corresponding opening of the pressure regulating valve is obtained, and the differential pressure limit control section outputs a differential pressure limit setting signal output from the differential pressure limit setting device and a differential pressure signal detecting the pressure difference between the inlet and outlet of the heater. Input the heater differential pressure signal output from the heater, command the opening of the pressure regulating valve so that the pressure difference becomes the pressure difference allowed by the heater, and, in the low-level signal selector, By inputting the pressure control signal output from the control unit and the differential pressure limiting control signal output from the differential pressure limiting control unit, the one with a smaller air flow rate of both signals, that is, the opening of the pressure regulating valve is smaller. Select the signal corresponding to Outputs Les the pressure regulating valve so that the valve opening is controlled. In this way, by combining the differential pressure limiting control unit and the low-level signal selector, depending on the pressure difference between the inlet and the outlet of the heater, the predetermined pressure control working state and the differential pressure limiting control state are automatically set. It can be switched.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a pressure control device for a blow-out type wind tunnel according to an embodiment of the present invention. In FIG. 1, 1 to 7, 9 and a are the same as the conventional example shown in FIG. Are denoted by the same reference numerals and detailed description thereof will be omitted.

In FIG. 1, reference numeral 20 denotes a pressure control device, which sets a target value of the stagnation pressure of the collecting cylinder 5 and outputs it as a pressure setting signal, and an output of this pressure setting device 21. A pressure control unit 22 that performs proportional / integral calculation with respect to a pressure signal to be described later, and performs various known controls such as feedforward control as necessary, and an allowable value of the pressure difference between the inlet and the outlet of the heater 4 are set. A differential pressure limit setting unit 23 that gives an allowable value of this pressure difference as a differential pressure limit setting signal, and a proportional / integral calculation with respect to the output from this differential pressure limit setting unit 23 and a heater differential pressure signal described later. The differential pressure limiting control unit 24 for performing the above, the pressure control signal output from the pressure setting unit 21 and the differential pressure limiting control signal output from the differential pressure limiting control unit 24 are input to open the opening degree of the pressure regulating valve 3. Select the signal corresponding to the smaller And a low signal selector 25 for. Reference numeral 15 is a differential pressure signal transmitter for detecting a pressure difference between the inlet and the outlet of the heater 4, which converts the pressure difference into an electric signal and transmits it to the differential pressure limiting control section 24.

Next, the operation of the above configuration will be described. The stagnation pressure of the collecting cylinder 5 is converted into an electric signal by the pressure transmitter 9 and transmitted to the pressure controller 22, and the pressure difference between the inlet and the outlet of the heater 4 detected by the differential pressure signal transmitter 15. Is converted into an electric signal and transmitted to the differential pressure limit control unit 24. Further, as the output of the pressure control device 20, the signal selected by the low-level signal selector 25 is transmitted to the pressure regulating valve 3, and the valve opening is automatically adjusted by the selected signal.

Now, the operations of the differential pressure limit control section 24 and the low level signal selector 25 will be described in more detail. At the initial stage of ventilation, the pressure control unit 22 rapidly opens the pressure regulating valve 3 to raise the pressure of the heater 4 and the collecting cylinder 5 at a low pressure to the pressure set by the pressure setter 21, and a large amount of air is heated by the heater 4. And it will be sent to the collecting cylinder 5. At this time, the pressure difference between the inlet and the outlet of the heater 4 temporarily increases and exceeds the allowable value given by the differential pressure limit setting unit 23.

FIG. 2 shows the response operation of each part of the pressure control device 20. The solid line in FIG. 2 shows the response in the above embodiment, and the broken line does not include the differential pressure limit control part 24. Shows the response. In FIG. 7C, when ventilation starts at point A, the opening degree of the pressure regulating valve 3 increases. However, at the point B, the pressure difference between the inlet and the outlet of the heater 4 is the differential pressure limit setter 23 as shown by C in FIG. 2B.
When the permissible value set in is reached, the differential pressure limit control unit 24
By the action of, the opening of the pressure regulating valve 3 is limited to suppress an increase in the pressure difference between the inlet and the outlet of the heater 4. Waiting for the pressure of the heater 4 to rise with the pressure difference between the inlet and the outlet of the heater 4 being limited, the pressure is set by the pressure setter 21 shown by D in FIG. 2 (a). When the pressure reached
The pressure difference gradually decreases, and the differential pressure limiting control shifts to the pressure control.

When the transient response as described above ends,
The pressure difference between the inlet and the outlet of the heater 4 is the differential pressure limit setting device 23.
Since the value is smaller than the allowable value C set in step 1, the low-order signal selector 25 selects the pressure control by the pressure controller 22 instead of the differential pressure limit control.

FIG. 3 is an overall configuration diagram of a blow-out type wind tunnel pressure control device according to another embodiment of the present invention. In FIG. 3, the difference from the above embodiment is that the differential pressure signal transmitter 15 is used. The second pressure transmitter 14 for transmitting the outlet pressure of the heater 4 is provided. Since other configurations are the same as those of the embodiment shown in FIG. 1, the same reference numerals are given to corresponding parts. And their description is omitted. In this embodiment, the pressure transmitter 9 used for pressure control is the first pressure transmitter, and the output from the first pressure transmitter 9 and the output from the second pressure transmitter 14 are Is input to the subtractor 26, the difference between the two is calculated, and the calculated value is calculated as the differential pressure limit control unit 24.
By inputting into, the same operation and action as in the above embodiment can be obtained.

The pressure control device of the present invention can be realized by combining known analog electronic circuits. However, even if a part or all of the arithmetic operations are performed by an electronic computer, the same effect as in the above embodiment is obtained. Play.

Further, in each of the above-mentioned embodiments, air is used as the working fluid, but a gas other than air, such as nitrogen or helium, may be used, and the same effect as in the above-mentioned embodiments is obtained. Furthermore, in each of the above embodiments, the pressure on the downstream side of the pressure regulating valve 3 which is easy to measure is used as the stagnation point pressure of the collecting cylinder 5, but in addition to this, for example, the heater 4
It is also possible to directly measure the outlet pressure and the stagnation point pressure of the collecting cylinder 5 and use the signal for control.

[0022]

As described above, according to the present invention, the pressure difference between the inlet and the outlet of the heater is increased by combining the differential pressure limiting control section and the low level signal selector, and the heat storage in the heater is increased. If there is a possibility that the body will float up, it will automatically switch to the differential pressure limit control state, and if the above-mentioned pressure difference becomes small and there is no possibility that the heat storage body will float up, the prescribed pressure control will be performed automatically. You can switch to the state. Therefore, it is possible to prevent the heater from being damaged even when the operating point is freely set without considering the floating of the heat storage body inside the heater, including the initial stage of ventilation.
Further, even during the trial operation, the operation can be performed without flowing an air flow rate higher than the preset value, and there is no possibility of damage to the heater due to trial and error. Furthermore, since the pressure control device can be adjusted separately from the floating of the heat storage body in the heater, the control parameters can be freely selected and the pressure control performance can be sufficiently exhibited.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a pressure control device for a blow-out type wind tunnel according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a pressure control operation.

FIG. 3 is an overall configuration diagram of a pressure control device for a blow-out type wind tunnel according to another embodiment of the present invention.

FIG. 4 is a general configuration diagram of a blow-out wind tunnel.

FIG. 5 is an overall configuration diagram of a conventional pressure control device for a blow-out type wind tunnel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Storage tank 3 Pressure regulating valve 4 Heat storage type heater 5 Collecting cylinder 6 Nozzle 9 First pressure transmitter 14 Second pressure transmitter 15 Differential pressure signal transmitter 20 Pressure controller 21 Pressure setter 22 Pressure controller 23 Differential pressure limit setter 24 Differential pressure limit controller 25 Low level signal selector

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Claims (2)

(57) [Claims] 1. A heat storage type heater, wherein high pressure compressed air stored in an air storage tank is passed through a pressure regulating valve and heated by a heat storage type heater.
Air and together are adapted to air to the nozzle via the collecting cylinder located between the nozzle, the pressure regulating valve
In a pressure control device for a blow-out type wind tunnel equipped with a pressure control unit for controlling the pressure of the collecting cylinder by adjusting the flow rate, the pressure difference allowed by the regenerative heater is set and output as a differential pressure limit setting signal. A differential pressure limit setting device, a differential pressure signal transmitter for outputting the pressure difference between the inlet and the outlet of the heater as a heater differential pressure signal, and a differential pressure limit setting signal output from the differential pressure limit setting device and When the heater differential pressure signal output from the differential pressure signal transmitter is input and the heater differential pressure signal becomes equal to or higher than the differential pressure limit setting signal, a differential pressure limit control signal for limiting the air flow rate is output. A differential pressure limiting control unit,
The pressure control signal output from the pressure control unit and the differential pressure limit control signal output from the differential pressure limit control unit are input, and a signal corresponding to the one with a smaller air flow rate is output to the pressure regulating valve. A pressure control device for a blow-out type wind tunnel, comprising: 2. The differential pressure signal transmitter comprises a first pressure transmitter for detecting pressure on the inlet side of the heater, a second pressure transmitter for detecting pressure on the outlet side of the heater, and these. 2. The pressure control device for a blow-out type wind tunnel according to claim 1, comprising a subtractor for calculating a difference between pressures detected by the first and second pressure transmitters.