JPH0629826B2 - Collecting cylinder pressure control device - Google Patents

Description

The present invention relates to a collecting cylinder pressure control device for a blow-out type wind tunnel, and more particularly to a mechanism for controlling the Mach number of an air flow (hereinafter referred to as a Mach number control device). The present invention relates to a collecting cylinder pressure control device for a blow-out type wind tunnel.

[Conventional technology]

As shown in FIG. 2, the blow-out type wind tunnel guides the compressed air accumulated in the storage tank 1 through the high-pressure conduit 2 and reduces the pressure to a constant pressure by the pressure regulating valve 3 whose valve opening can be adjusted by a signal from the outside. After that, it has a schematic configuration of discharging to the atmosphere via a collecting cylinder (also called a rectifying cylinder) 4, a nozzle 5, and a measuring unit 6 that regulates the flow of the air flow. Aerodynamic measurements can be performed.

As described above, in the blow-out wind tunnel, ventilation is performed only by releasing the compressed air accumulated in the storage tank 1, and therefore the ventilation time is limited to an extremely short time (usually several seconds to several tens of seconds). During this time, the measurement must be completed.
Further, if the compressed air inside the storage tank 1 is discharged by ventilation, it takes a long time (typically several hours) to refill the storage tank 1 with the compressed air. Therefore, in the control device of the blow-out type wind tunnel, not only the accuracy for guaranteeing the reproducibility of the experiment but also the high-speed responsiveness of controlling the air flow inside the wind tunnel to a desired state within a short time is required.

FIG. 3 is a block diagram of a conventional collecting cylinder pressure control device for a blow-out type wind tunnel. This device opens the pressure regulating valve 3 so that the total pressure (stagnation point pressure) of the collecting cylinder 4 becomes a predetermined value. It has a function of adjusting the degree.

In FIG. 3, a collective-cylinder pressure control device 10 takes a difference between a collective-cylinder pressure setting device 11 for setting a pressure in the collective cylinder and an output of the collective-cylinder pressure setting device 11 and a collective-cylinder pressure described later. A subtracter 12, a feedback control unit 13 that performs proportional and integral calculations on the output of the subtractor 12, and a gain converter 14 that adjusts the gain of the output of the feedback control unit 13 according to the pressure of the storage tank. I have it.

Such a conventional collecting cylinder pressure control device inputs the pressure signal in the collecting cylinder 4 detected by the collecting cylinder pressure transmitter 7, and deviates from the collecting cylinder pressure setting signal output from the collecting cylinder pressure setter 11. Is calculated by the subtracter 12, and the feedback controller 13 performs proportional and integral calculations on this deviation. Gain conversion according to the pressure signal in the storage tank 1 output from the storage tank pressure transmitter 8 with respect to the feedback control signal output from the feedback control unit 13 is performed.
In step 4, the pressure regulating valve opening signal is output to the pressure regulating valve 3 so that the stagnation pressure of the collecting cylinder 3 becomes a predetermined pressure.

As a collecting cylinder pressure control device, various proposals have been made in the past, such as TR-647 of Aerospace Research Institute, JP-A-61-138304, JP-A-63-256835.

All of these control the pressure regulating valve 3 only by the feedback control unit 13 as described above, but in the Aerospace Research Institute Report TR-647 and Japanese Patent Laid-Open No. 63-256835, the gain converter is used. 14, the gain conversion of 1 / P _T (P _T indicates a storage tank pressure signal) is performed to compensate for the characteristic change of the pressure regulating valve due to the decrease in the storage tank pressure. In 138304, the collecting cylinder pressure transmission characteristic of the wind tunnel is measured during ventilation, and the gain and integration time are set online based on the results.

In such a conventional blow-out wind tunnel, it is considered sufficient if the collecting cylinder pressure control device can maintain the collecting cylinder pressure at a constant value under a constant Mach number, that is, a constant air flow rate at the measurement unit. It was extremely rare to change the collecting cylinder pressure and Mach number during one ventilation due to the difficulty of control.

On the other hand, with the rapid progress of aircraft in recent years and the improvement of wind tunnel measurement technology using computers, the Mach number and collecting cylinder pressure are changed in the middle of one ventilation,
It has been desired to measure transient response and obtain more sophisticated data.

[Problems to be Solved by the Invention]

However, in the conventional collecting cylinder pressure control device, if the proportional gain corresponding to 1 / P _T is simply used, it is necessary to reset the proportional gain each time the pressure setting value of the collecting cylinder is changed. However, there is a problem that the operation becomes complicated.

In addition, the amount of air passing through the pressure regulating valve changes depending on the pressure upstream and downstream of the pressure regulating valve, but generally the air pressure in the storage tank gradually decreases with ventilation, so the pressure on the upstream side and the pressure on the downstream side of the pressure regulating valve approach each other. , The air volume at the same valve opening decreases. That is, although the flow rate gain of the pressure regulating valve is reduced, the gain of the storage tank is reduced to 1 / P _T, and the storage tank pressure is significantly reduced. Cannot be fully compensated.

Further, if the proportional gain is set based on the measurement result during ventilation as in Japanese Patent Laid-Open No. 61-138304, an appropriate setting can be made, but the configuration of the control device becomes complicated and lacks reproducibility. There is a problem that the optimum proportional gain cannot be determined without ventilation.

The present invention is made in order to eliminate the drawbacks of the conventional collecting cylinder pressure control device by the feedback control, and simplifies the operation at the time of changing the Mach number setting value and the collecting cylinder pressure setting value, and An object of the present invention is to provide a collecting cylinder pressure control device capable of obtaining an appropriate control gain at the end of ventilation.

[Means for Solving the Problems]

According to the present invention, in the collecting cylinder pressure control device for controlling the pressure in the collecting tunnel of the blow-out type wind tunnel, which is equipped with the control mechanism for controlling the air flow by the compressed air stored in the storage tank, the stagnation pressure of the collecting cylinder Collecting cylinder pressure setter that outputs the collecting cylinder pressure setting signal that commands the set value, collecting cylinder pressure transmitter that outputs the stagnation point pressure detection value of the collecting cylinder as a collecting cylinder pressure signal, and pressure in the storage tank is detected For the storage tank pressure transmitter that outputs as a storage tank pressure signal, the collecting cylinder pressure setting signal output from the collecting cylinder pressure setting device, and the collecting cylinder pressure signal output from the collecting cylinder pressure transmitter A feedback control unit that performs a control calculation and calculates a feedback control signal for controlling the stagnation pressure detection value of the collecting cylinder to the value set by the collecting cylinder pressure setter and outputs the valve opening command signal of the pressure regulating valve. , Storage tank pressure generation And a gain converter for calculating a proportional gain with respect to a valve opening command signal based on these signals, which receives a storage tank pressure signal output from the container and a collecting cylinder pressure setting signal output from the collecting cylinder pressure setting device. It is characterized by that.

[Work]

According to the present invention, the proportional gain is increased in order to compensate for the decrease in air volume due to ventilation. That is, the decrease in the flow rate gain of the pressure regulating valve is compensated by increasing the proportional gain. Therefore, even when the pressure setting value of the collecting cylinder is changed or when the pressure of the storage tank is significantly reduced at the end of ventilation, the operation can be simplified and optimum gain compensation can be obtained. Further, the set value of the proportional gain can be grasped before ventilation.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to FIG. 1 which is a block diagram showing a configuration of an embodiment of the present invention.

The collecting cylinder pressure control device 20 in FIG. 1 sets a target value of the collecting cylinder pressure and outputs a collecting cylinder pressure setting signal indicating the target value of the collecting cylinder pressure, as in the conventional device. A feedback control unit 23 that performs proportional and integral calculations with respect to the output of the pressure setter 21 and the stagnation pressure of the collecting cylinder to be described later, and outputs the feedback control signal
Gain calculator 24 to adjust the output gain of the feedback control unit 23 is provided by the output P _t which is converted into an electric signal by the gas storage tank pressure transmitter 8 for detecting the pressure of the gas storage tank 1. On the other hand, the total pressure (stagnation point pressure) of the collecting cylinder 4 is converted into an electric signal in the collecting cylinder pressure transmitter 7 and transmitted to the subtractor 22 described above. Further, unlike the conventional device, the setting signal P _{O of the} collecting cylinder pressure setting device 20 is directly given to the gain converter 24, and the gain conversion is P
Two signals of _t and P _O are used as parameters. As an output of such a collecting cylinder pressure control device 20, a signal of the calculation result of the gain calculation unit 24 is transmitted to the pressure regulating valve 3 and the valve opening degree is adjusted.

Here, the storage tank pressure and the collecting cylinder pressure set value are used to control the valve opening for the following reason.

Originally, in order to control the pressure regulating valve, it is desirable to perform control by using the pressure regulating valve upstream side pressure and downstream side pressure. First,
Looking at the upstream side, the pressure becomes unstable in the high-pressure conduit section, which is the upstream side of the pressure regulating valve, so the pressure in the storage tank where the pressure is more stable than here is estimated as the pressure on the upstream side of the pressure regulating valve. did. Since the pressure loss due to the high-pressure conduit is small, the difference is small even if the pressure in the storage tank is adopted, and there is no particular problem.

On the other hand, regarding the pressure on the downstream side of the pressure regulating valve, the downstream side of the pressure regulating valve is the collecting cylinder, but for this pressure, a more stable collecting cylinder pressure set value is used instead of the collecting cylinder pressure detected by the collecting cylinder pressure transmitter. To do. This is because the blow-out type wind tunnel is a precision machine manufactured with extremely high precision, and since it is possible to control the collecting cylinder pressure according to the set value, the collecting cylinder pressure set value is used instead.

Next, the relationship between the pressure control valve opening and the air volume when the storage tank pressure and the collecting cylinder pressure set value are used will be described.

The relational expression between the pressure regulating valve opening and the air volume can be obtained according to the characteristics of the pressure regulating valve, but for optimum control of the pressure regulating valve, the relational expression is the reverse of this relational expression, that is, the pressure regulating valve opening is proportional to the air volume. By setting the gain, it becomes possible to cancel the relational expression between the pressure control valve opening degree and the air volume.

Now, assuming that the upstream pressure of the pressure regulating valve is the storage tank pressure P _T , the downstream pressure is the collecting cylinder pressure set value P ₀ , and the pressure regulating valve opening degree is θ,
The air volume X _G determined by these is given by the following equation.

In case of (non-choke state) (Choke state) X _G = C1 ′ · P _T · θ (2) where k is the specific heat ratio of air, normally k = 1.4, C ₁ ,
C ₁ ′ is a constant determined by the pressure regulating valve.

A conventional collecting cylinder pressure control device, for example, the above-mentioned document, Aerospace Research Institute report TR-647 and JP-A-63-2.
The gain compensation performed at 56835 is for the choked state.

Based on such a relationship, in the above-described gain calculation unit 24, the storage tank pressure signal P _T sent from the storage tank pressure transmitter 8 and the collecting cylinder pressure setting sent from the collecting cylinder pressure setter 21 are set. The following calculation, which is an inverse relational expression to the above calculation, is performed with the signal P ₀ to obtain the coefficient V _G representing the variable gain in the gain converter 21.

In case of (non-choke state) In case of (choke state) However, C ₂ , C ₂ ′ are constants, and these conditional expressions and gain calculation expressions are
It is stored in the internal memory.

According to the collecting cylinder pressure control device as described above, it is determined according to the collecting cylinder pressure set value P ₀ and the storage tank pressure P _T that the choke state is present, and the non-choke state is determined, and each state is dealt with. Select the formula to calculate. Therefore, in the choke state where the storage tank pressure P _T is sufficiently high,
The same performance as before is demonstrated by the gain from equation (4).
The gain is calculated by Eq.

The collecting cylinder pressure control device according to the present invention can be configured by combining analog electronic circuits, and a part or all thereof can be realized by an electronic computer.

In the above-mentioned embodiment, the working fluid is air, but the present invention can obtain the same effect even when a gas other than air, such as nitrogen or helium, is used.

[Advantages of the Invention] As described above, according to the present invention, the proportional gain is increased in order to compensate for the decrease in air volume due to ventilation, and therefore, when the pressure set value of the collecting cylinder is changed and when ventilation is completed, Even when the tank pressure drops significantly, the operation can be simplified and optimum gain compensation can be obtained. Further, since the set value of the proportional gain can be confirmed before ventilation, drivability is improved and stable operation can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a collecting cylinder pressure control device according to the present invention, FIG. 2 is a schematic explanatory view showing a typical blowout type wind tunnel, and FIG. 3 is a conventional collecting cylinder pressure control. It is a block diagram of an apparatus. 1 ... Storage tank, 2 ... High-pressure conduit, 3 ... Pressure regulating valve, 4 ...
Collecting cylinder, 7 ... Collecting cylinder pressure transmitter, 8 ... Storage tank pressure transmitter, 20 ... Collecting cylinder pressure control device, 21 ... Collecting cylinder pressure setting device, 23 ... Feedback control unit, 24 ... Gain calculator.

Claims (1)

[Claims] 1. A collecting cylinder pressure control device for controlling a pressure in a collecting tunnel of a blow-out type wind tunnel, comprising a control mechanism for controlling a flow of compressed air stored in a storage tank, and a stagnation pressure of the collecting cylinder. A collecting cylinder pressure setting device that outputs a collecting cylinder pressure setting signal that commands a setting value, a collecting cylinder pressure transmitter that outputs a stagnation point pressure detection value of the collecting cylinder as a collecting cylinder pressure signal, and a pressure of the storage tank And a collecting cylinder pressure setting signal output from the collecting cylinder pressure setter, and a collecting cylinder pressure output from the collecting cylinder pressure transmitter. A control calculation is performed on the signal, and a feedback control signal for controlling the stagnation pressure detection value of the collecting cylinder to a value set by the collecting cylinder pressure setting device is calculated to output a valve opening command signal of the pressure regulating valve. Feedback The control unit receives the reservoir pressure signal output from the reservoir pressure transmitter and the collecting cylinder pressure setting signal output from the collecting cylinder pressure setter, and based on these signals, the valve opening command signal. And a gain converter that calculates a proportional gain with respect to the collecting cylinder pressure control device.