JP2002303563A - Device for controlling collection tunnel pressure of blowout type wind tunnel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deformation and breakage of a straightening member 63 such as a punching metal in a collection tunnel and a model 64 or the like in a measurement chamber 58 by preventing a phenomenon that a pressure in the collection tunnel 56 of a blowout type wind tunnel fluctuates periodically positively and negatively during stop of ventilation measurement. SOLUTION: An opening of a regulator 55 is controlled so that the pressure in the collection tunnel 56 detected by a sensor 71 during the ventilation measurement becomes a pressure P1 for ventilation measurement set by a pressure setting means 72 for ventilation measurement. The opening of the regulator 55 is controlled so that a pressure P2 detected by the sensor 71 during stop of the measurement becomes the atmospheric pressure P0 set by an atmospheric pressure setting means 73. Thereby, during the stop of the measurement, the pressure in the collection tunnel 56 is maintained to the atmospheric pressure. Therefore, the pressure in the collection tunnel 56 does not fluctuate periodically, and the air flows in one direction the same as during the ventilation measurement and without flow back.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure control device for a collective cylinder of a blow-out type wind tunnel.

[0002]

2. Description of the Related Art FIG. 11 is a system diagram of the prior art. In the blow-out type wind tunnel 21, the air storage tank 22 is filled with compressed air at high pressure, and at the time of ventilation measurement, the main valve 23 interposed in the pipeline 46 is opened, and the compressed air is sent from the pressure regulating valve 24 to the collecting cylinder 25. It flows into the measuring chamber 27 where the model to be subjected to the ventilation measurement is to be arranged from the first throat section 26, is decelerated from the second throat section 28 through the diffusion cylinder 29, and is released to the atmosphere through the silencer 31. . A plurality of flow regulating members 32 are provided in the collecting cylinder 25 along the flow direction. The rectifying member 32 functions to rectify the compressed air to the measurement chamber 27 and make the pressure distribution uniform in a cross section perpendicular to the flow direction of the compressed air. The rectifying member 32 is made of, for example, a wire mesh, a perforated plate, or a punching metal.

When the measurement is stopped, the fully closed command signal generating means 34
Is supplied from a switch 35 to a subtraction means 36, which includes a position of a valve body of the pressure regulating valve 24,
That is, the output of the position detecting means 37 for detecting the stroke of the pressure regulating valve 24 is provided. The output of the fully closed command from the subtracting means 36 is given to the position control means 38, and the valve body of the pressure regulating valve 24 is driven to be displaced by the pressure regulating valve driving means 39.
Thus, the pressure regulating valve 24 is maintained in the fully closed state by the output of the fully closed command signal generating means 34.

At the time of ventilation measurement, with the main valve 23 open, compressed air flows from the pressure regulating valve 24 into the collecting cylinder 25, and ventilation measurement is performed. The output indicating the ventilation measurement pressure set by the pressure setting means 41 is given to another subtraction means 42. The subtracting means 42 includes the collecting cylinder 25
An output from a sensor 43 that detects the pressure in the chamber is also provided. The output of the subtraction means 42 is given to the pressure control means 44. The pressure of the pressure control means 44 passes through a switch 45 switched for ventilation measurement from the time of stoppage, and
4 is provided to a subtraction means 36 for driving. At this time, the switch 35 is shut off. The pressure regulating valve driving means 39 drives the valve body of the pressure regulating valve 24 so that the pressure detected by the sensor 43 in the collecting cylinder 25 is maintained at the ventilation measurement pressure set by the pressure setting means 41. .

After the measurement of the ventilation, the switch 45 is turned off again, and the switch 35 is turned on, whereby the pressure regulating valve 24 is fully closed.

FIG. 12 is a graph showing experimental results of the prior art shown in FIG. 11 by the present inventor. Time t1
Previously, the main valve 23 was fully opened, the switch 35 was closed as shown in FIG. 11, and the switch 45 was open.
At time t1, the switch 35 is switched to start ventilation measurement. At the time t2 at which the measurement is stopped, the switch 35 is closed and the switch 45 is opened to keep the pressure regulating valve 24 in a fully closed state. The contents indicated by the lines a to a in FIG. 12 are as shown in Table 1.

[0007]

[Table 1]

In FIG. 12, lines a, a; a;
The position of the vertical axis in FIG. 12 representing the atmospheric pressure of a is different for convenience of illustration, and the position of the atmospheric pressure is indicated by reference numeral 11 with respect to the lines a, a and by reference numeral with respect to the line a. 14 and reference 1 for line a
Indicated by 7.

As shown by a line a in FIG. 12, after the measurement stop time t2, the pressure in the collecting cylinder 25 becomes 1 at atmospheric pressure.
7, the static pressure in the measurement chamber 27 periodically fluctuates above and below the atmospheric pressure. The present inventor has found that such a periodic fluctuation of the pressure in the collecting cylinder 25 occurs.

The inventor of the present invention explains the reason why such a phenomenon of periodic fluctuation of pressure occurs as follows. That is, when the pressure control valve 24 is fully closed at the maximum value of the rate of change of the opening degree of the pressure control valve 24 during the closing time at the time t2, the high-pressure compressed air accumulated in the collecting cylinder 25 is discharged to the first throat portion. 26, measuring chamber 27, second throat section 28, diffusion cylinder 2
After passing through 9, the gas is exhausted from the silencer 31. At this time, due to the state of the first and second throat portions 26 and 27 and the pressure in the collecting cylinder 25, the flow of air from the collecting cylinder 25 is reduced, and the pressure in the collecting cylinder 25 is lower than the atmospheric pressure due to the inertial force of the air. , The collecting cylinder 25 and the measuring chamber 27 are kept in a negative pressure state. When the collecting cylinder 25 becomes negative pressure,
Air flows into the collecting drum 25 through the silencer tower 31, the diffusion drum 29, the second throat portion 28, the measurement chamber 27, and the first throat portion 26, and flows backward. Thereby, the pressure in the collecting cylinder 25 becomes higher than the atmospheric pressure. A phenomenon occurs in which such positive and negative fluctuations in pressure are repeated from two to three times to 12 to 13 times.

After the pressure regulating valve 25 is fully closed as described above, the pressure in the collecting cylinder 25 periodically fluctuates in the positive and negative directions, thereby deforming and breaking the rectifying member 32 and causing the measurement chamber 27 to move.
The noise in the low-frequency range is generated by adverse effects on the model inside (intrusion of foreign matter from the silencer, influence on the detector, and the like), and furthermore, external air is sucked in and exhausted from the silencer 31.
Although the rectifying member 32 has sufficient strength to withstand high-pressure compressed air flowing from the pressure regulating valve 24 side, reinforcement for the air flow in the opposite direction is not performed, and as described above, the rectifying member 32 has a long Deformation and breakage during use. Even if these are not necessarily broken, they will be broken after long-term use. Prolonged use results in shortened life. Therefore, no damage that does not result in damage has been found in the prior art.

It is conceivable to reinforce the rectifying member 32 in order to prevent the air from flowing backward due to the negative pressure inside the collecting cylinder 25 and deforming or damaging the rectifying member 32. The pressure loss due to the rectifying member 32 increases. Therefore, the measurement result in the measurement chamber 27 is adversely affected.

Prior art techniques for controlling the pressure of a collecting cylinder of a blow-out type wind tunnel include, for example, Japanese Patent Publication No. 6-19301 and Japanese Patent Publication No. 6-1.
9302 and Japanese Patent Publication No. 6-29826. These prior arts also have the same problems as the prior arts shown in FIGS. 11 and 12 described above.

In summary, in the prior art, a phenomenon is known in which the pressure in the collecting cylinder 25 periodically fluctuates above and below the atmospheric pressure when the collecting cylinder is fully closed by the pressure regulating valve after the measurement of the ventilation is stopped. Not. Therefore, in the prior art, no motivation has been made to solve the above-mentioned problems caused by such a phenomenon.

[0015]

SUMMARY OF THE INVENTION It is an object of the present invention to stop a ventilation measurement, terminate the operation, and prevent a phenomenon in which the pressure in the collecting cylinder fluctuates periodically. It is to provide a pressure control device.

[0016]

According to the present invention, a compressed air stored in an air storage tank is guided to a collecting cylinder from a pressure regulating valve having a variable opening, and a throat section and a measuring section are provided downstream of the collecting cylinder. Are provided in series, a sensor 71 for detecting the pressure in the collecting cylinder, and a ventilation measuring pressure for setting a predetermined ventilation measuring pressure in the collecting cylinder during ventilation measurement. In response to the output of the setting means 72, the sensor and the pressure setting means for ventilation measurement, the opening degree of the pressure regulating valve is controlled so that the detection pressure of the sensor becomes the pressure for ventilation measurement during ventilation measurement, and the measurement is stopped. In order to reduce the opening of the pressure regulating valve to less than the opening during ventilation measurement, or to control the valve fully closed, and at the time of stoppage, the pressure in the collecting cylinder should be And means for preventing negative pressure for introducing air. A collecting cylinder pressure controller Shikifudo.

According to the present invention, as will be described later with reference to FIGS. 1 to 10, in a blow-out type wind tunnel, which is a kind of an intermittent type wind tunnel, a compressed air is filled in an air storage tank and stored therein. The flow rate of high-pressure compressed air in the air tank into the collecting cylinder is controlled by a pressure regulating valve,
The pressure during the ventilation measurement inside the collecting cylinder is set to a desired predetermined pressure. The predetermined pressure may be a constant value during the ventilation measurement, or may be a value that changes with time. The high-pressure compressed air of the collecting cylinder passes through the throat part and creates a high-speed airflow for about 10 to 60 seconds in the measuring unit where the model is arranged. This high-speed airflow is transmitted from the measurement unit to another
The two throats may be decelerated via a diffuser and configured to pass through a muffler tower, thus being vented to the atmosphere.

When the measurement of the ventilation is stopped, the opening of the pressure regulating valve is made smaller than the opening during the measurement of the ventilation or is completely closed by the control means. At the time of the stop, the pressure in the collecting cylinder does not become negative. Then, air is introduced into the collecting cylinder by the negative pressure prevention means shown in FIGS. Although this air may be configured to be introduced into the collecting cylinder via the pressure regulating valve, in another embodiment of the present invention, the air upstream from the pressure regulating valve through which the compressed air from the air storage tank is guided is provided. The compressed air from the pipe of the collecting cylinder may be introduced into the collecting cylinder, or the outside air may be supplied into the collecting cylinder. It is configured so that the pressure does not become negative.

In the prior art, when the measurement of ventilation is stopped, that is, after the operation is stopped, the pressure in the collecting cylinder becomes lower than the atmospheric pressure and becomes a negative pressure, which causes a reciprocating movement of air into the collecting cylinder. Have not been discovered, and thus there is no motivation to solve such problems. The inventor of the present invention has a phenomenon that the pressure of the air in the collecting cylinder periodically fluctuates due to the negative pressure in the collecting cylinder or periodically,
Discovered as described above. According to the present invention, the negative pressure preventing means for preventing the pressure in the collecting cylinder from becoming negative pressure is provided, whereby the reciprocating movement of the air can be prevented when stopping in the collecting cylinder. Therefore, it is possible to prevent deformation and shortening of the life of the rectifying means provided in the collecting cylinder, and to prevent adverse effects on the model in the measuring chamber connected to the collecting cylinder via the throat portion.

Further, according to the present invention, the compressed air stored in the air storage tank is guided to the collecting cylinder from a pressure regulating valve whose opening degree is variable, and a throat section and a measuring section are provided in series downstream of the collecting cylinder. In the collective cylinder pressure control device of the blow-out type wind tunnel, a sensor 71 for detecting a pressure in the collective cylinder, a ventilation measurement pressure setting means 72 for setting a predetermined ventilation measurement pressure in the collective cylinder during ventilation measurement, Atmospheric pressure setting means 73 for setting the atmospheric pressure, in response to the output of the sensor and the pressure setting means for ventilation measurement and the atmospheric pressure setting means, during ventilation measurement, so that the detection pressure of the sensor becomes the pressure for ventilation measurement, And means for controlling the opening of the pressure regulating valve so that the pressure in the collecting cylinder becomes the atmospheric pressure when the measurement is stopped.

Further, according to the present invention, the control means includes a switching means 74 for switching and outputting the outputs of the ventilation measurement pressure setting means and the atmospheric pressure setting means, and a subtracting means for calculating a difference between the outputs of the sensor and the switching means. 78 and in response to the output of the subtraction means,
Pressure regulating valve drive control means for controlling the opening of the pressure regulating valve so that the difference becomes zero.

According to the present invention, as shown in FIGS. 1 to 4, during ventilation measurement, the pressure detected by the sensor in the collecting cylinder is determined in advance by the ventilation measurement pressure setting means. The opening degree of the pressure regulating valve is controlled so as to be a ventilation measurement pressure. When the ventilation measurement is stopped, that is, after the operation is completed, the opening of the pressure regulating valve is controlled such that the pressure in the collecting cylinder detected by the sensor becomes the atmospheric pressure set by the atmospheric pressure setting means 73. . Therefore, the pressure in the collecting cylinder does not become a negative pressure, and the reciprocating movement of the air in the collecting cylinder is eliminated.

The control means includes a switching means 74 for switching a set value between the ventilation measurement pressure and the atmospheric pressure. The difference between the output of the sensor and the output of the switching means is subtracted by a subtraction means 78, and the pressure regulating valve drive control is performed. The opening of the pressure regulating valve is drive-controlled by the means. As a result, the pressure detected by the sensor in the collecting cylinder is maintained at the ventilation measurement pressure or the atmospheric pressure.

Further, according to the present invention, the compressed air stored in the air storage tank is guided to the collecting cylinder from a pressure regulating valve whose opening degree is variable, and a throat section and a measuring section are provided in series downstream of the collecting cylinder. In a collective cylinder pressure control device for a blow-out type wind tunnel, a sensor for detecting a pressure in the collective cylinder, a ventilation setting pressure setting means for setting a predetermined ventilation measurement pressure in the collective cylinder during ventilation measurement, and an atmospheric pressure In response to the outputs of the atmospheric pressure setting means, the sensor, the ventilation pressure setting means and the atmospheric pressure setting means, during the ventilation measurement, the detection pressure of the sensor becomes the ventilation measurement pressure, and When stopped, a gradual decrease time change rate a that is less than the maximum value of the pressure decrease time change rate of the collection cylinder pressure setting so that the pressure in the collection cylinder becomes the atmospheric pressure.
And a means for controlling the pressure of the blow-out type wind tunnel.

According to the present invention, as shown in FIG.
The time change rate of the signal for setting the atmospheric pressure from the atmospheric pressure setting means is controlled to be small by the limiter 92 or the like, so that the rate of decrease in the pressure in the collecting cylinder is moderated to prevent the pressure from becoming negative. it can. The rate of change of the drop time for changing the setting of the collecting cylinder pressure is set to a gentle value a, and the rate of change of the drop time is set to a value a less than the maximum rate of change of time. In this way, when the ventilation measurement is stopped, the phenomenon that the collecting cylinder pressure gradually decreases and the negative pressure inside the collecting cylinder becomes negative can be avoided. The limiter 92 in FIG. 2 is a time change rate limiter of the pressure set value, and is not a valve closing time change rate limiter of the pressure regulating valve 55. The valve closing time change rate limiter of the pressure regulating valve is indicated by reference numeral 99 in FIG.

According to the present invention, the control means includes switching means for switching and outputting the outputs of the ventilation measurement pressure setting means and the atmospheric pressure setting means, and subtraction means for calculating the difference between the outputs of the sensor and the switching means. In response to the output of the subtracting means, the pressure regulating valve drive control means for driving and controlling the opening of the pressure regulating valve so that the difference becomes zero is interposed between the atmospheric pressure setting means and the pressure regulating valve drive control means. A limiter 92 for limiting the rate of change a in pressure drop time of the setting of the collecting cylinder pressure to less than a predetermined value.
And characterized in that:

According to the present invention, the control means for controlling the falling time rate of change of the setting of the collecting cylinder pressure to a small value includes a limiter 92 relating to the falling time rate of change, thereby preventing a sudden change in the collecting cylinder pressure. It is possible to suppress the decrease time change rate a from becoming a large value. Therefore, the collecting cylinder pressure is gradually reduced when the operation is stopped. In this way, the pressure regulating valve gradually closes, so that the pressure in the collecting cylinder can be prevented from becoming negative.

Further, according to the present invention, the compressed air stored in the air storage tank is guided to the collecting cylinder from a pressure regulating valve whose opening degree is variable, and a throat section and a measuring section are provided in series downstream of the collecting cylinder. In a collective cylinder pressure control device for a blow-out type wind tunnel, a sensor for detecting pressure in the collective cylinder, a pressure setting means for ventilation measurement for setting a predetermined pressure for ventilation measurement in the collective cylinder during ventilation measurement, and a pressure regulating valve The output of the fully-closed command signal generating means 88 for generating a fully-closed command signal for fully closing and the output of the fully-closed command signal generating means are adjusted so that the pressure in the collecting cylinder does not become negative when the measurement is stopped. A valve closing time rate of change limiter 99 that changes with time at a gradual valve closing time rate of change b that is less than the maximum value of the valve closing time rate of change of the opening degree of the pressure valve, a sensor and a pressure setting means for ventilation measurement Response to the output of the valve closing time change rate limiter During measurement, the opening of the pressure regulating valve is controlled so that the detection output of the sensor becomes the pressure for ventilation measurement, and when the measurement is stopped, the opening of the pressure regulating valve is driven and controlled by the output of the valve closing time change rate limiter. And a drive control means.

According to the present invention, as shown in FIG.
When the ventilation measurement is stopped, the fully-closed command signal from the fully-closed command signal generating means 88 is corrected by the valve-closing time rate-of-change limiter 99 to a gentle valve-closing time change rate b, and the opening of the pressure regulating valve is sharply increased. Restrict valve closing action. This also prevents the pressure in the collecting cylinder from becoming negative and causing reciprocation of air.

Further, according to the present invention, the compressed air stored in the air storage tank is guided to the collecting cylinder from a pressure regulating valve whose opening degree is variable via a pipe, and a throat section and a measuring section are provided downstream of the collecting cylinder. In a collective cylinder pressure control device for a blow-out type wind tunnel provided in series, a sensor for detecting a pressure in the collective cylinder, and a ventilation setting pressure setting means for setting a predetermined ventilation measurement pressure in the collective cylinder during ventilation measurement , A connecting pipe 104 connecting the pipe and the collecting cylinder, and a negative pressure prevention valve 105 interposed in the connecting pipe.
During ventilation measurement, the negative pressure prevention valve is fully closed, and when measurement is stopped, the negative pressure prevention valve is opened and compressed air in the pipeline is collected so that the pressure in the collection cylinder does not become negative. And a control unit for introducing the pressure into the inside of the air blower.

The present invention also provides a throttle 1 interposed in a connecting pipe.
08 is further included.

Further, the present invention is characterized in that the negative pressure preventing means is a check valve 109 provided in the collecting cylinder and for introducing outside air when the pressure in the collecting cylinder becomes negative.

According to the present invention, FIGS. 8, 9 and 10
As shown in the figure, the compressed air in the conduit for guiding the compressed air from the air storage tank from the collecting cylinder to the pressure regulating valve passes through the connecting pipe 104 and the negative pressure prevention valve 105, and when the ventilation measurement is stopped, To prevent the pressure in the collecting cylinder from becoming negative when the operation is stopped.

According to the present invention, as shown in FIG. 9, it is also possible to further provide a throttle 108 in the negative pressure check valve so that the opening and closing operation of the negative pressure check valve can be performed accurately. As shown in, a check valve 109 is provided on the collecting cylinder,
When the pressure in the collecting cylinder becomes negative, outside air is taken into the collecting cylinder from the outside.

[0035]

FIG. 1 is a system diagram of an embodiment of the present invention. In the blow-out type wind tunnel 51, the air storage tank 52 is filled with compressed air at a high pressure of, for example, 12 kg / cm ² or more. The compressed air from the air storage tank 52 flows into the collecting cylinder 56 from the pressure regulating valve 55 via the main valve 54 through the pipe 53. A first throat portion 57, a measurement chamber 58, and a second throat portion 59 are arranged in the collecting cylinder 56 in this order from left to right in FIG. 1 along the flow direction of the compressed air. The second throat portion 59 is further connected to a diffusion drum 61 for decelerating the compressed air.
Is connected, and the compressed air is released to the atmosphere. A plurality of flow regulating members 63 are provided in the collecting cylinder 56 along the flow direction. The rectifying member 63 functions to rectify the compressed air to the measurement chamber 58 and to make the pressure distribution uniform in a cross section perpendicular to the flow direction of the compressed air. Rectifying member 6 for this compression
3 may be made of, for example, a wire mesh, a perforated plate, a punched metal, a honeycomb plate, or the like. The rectifying member 63 is installed so as not to be deformed or damaged by the flow of the compressed air from the pressure regulating valve 55 downstream (to the right in FIG. 1). In the measurement chamber 58, a model 64 on which a wind tunnel test is to be performed is arranged.

The pressure regulating valve 55 is configured such that a valve body 66 can be displaced toward and away from a valve seat 65 provided near a connection portion of the collecting cylinder 56 with the conduit 53. When the valve element 66 is seated in contact with the valve seat 65, the pressure regulating valve 55
Is a fully closed state. The opening is increased by the valve body 66 being displaced away from the valve seat 65 to the right in FIG. Valve 6
6 is driven reciprocally by a pressure regulating valve driving means 67 including a hydraulic cylinder and the like, whereby the opening of the pressure regulating valve 55 is changed. The position of the valve body 66 and therefore the pressure regulating valve 55
Is detected by the position detecting means 68.

The pressure P2 of the air in the collecting cylinder 56 is detected by the sensor 71. During the measurement of the ventilation, for example, 1.
5 kg / cm ² or more. Ventilation measurement pressure setting means 7
2 sets a predetermined ventilation measurement pressure P1 in the collecting cylinder 56 during ventilation measurement. Atmospheric pressure setting means 73
A signal for setting the pressure of the air in the collecting cylinder 56 to the atmospheric pressure P0 is derived. Each output of these setting means 72, 73 is
Each of the switches 75 and 76 of the switching means 74 is connected. Outputs of these switches 75 and 76 are supplied to one input of a subtraction means 78 via a line 77.
A signal representing the pressure P2 detected by the sensor 71 is provided to the other input of the subtracting means 78. In the switching means 74, when the ventilation measurement is stopped, the switch 75 is turned off and the switch 76 is kept on as shown in FIG. During the ventilation measurement, the switch 75 is turned on and the switch 76 is turned off. The pressure control deviation P12 represented by the signal derived from the line 79 of the subtracting means 78 is P12 = P0−P2 when the ventilation measurement is stopped, and P12 = P0−P2 during the ventilation measurement.
12 = P1-P2.

The signal output from the subtracting means 78 to the line 79 is supplied to the pressure control means 81. The pressure control means 81 is provided with a pressure regulating valve 55 corresponding to the pressure control deviation P12.
, And thus a signal representing the stroke position of the valve element 66 of the pressure regulating valve 55 is derived to a line 82. The forced stop switching means 83 has switches 84 and 85. A signal derived from the pressure control means 81 to a line 82 is supplied to one input of a subtraction means 87 from a line 86 via a switch 84.

The output of the fully closed position setting means 88 which outputs a command signal indicating the fully closed position at which the valve body 66 of the pressure regulating valve 55 is seated on the valve seat 65 to be fully closed is supplied via a switch 85 to a line. 86 is given to the subtraction means 87. In the forced stop switching means 83, during normal ventilation measurement, the switch 84 is conducting and the switch 85 is off. When an abnormality occurs during the ventilation measurement and the pressure regulating valve 55 should be fully closed,
Or, when the ventilation measurement is stopped, the valve body 66 of the pressure regulating valve 55
Is to be seated on the valve seat 65 to be in the fully closed state, the stop compulsory switching means 83 performs a switching operation, the switch 84 is turned off, and the switch 85 is turned on.

The output of the position detecting means 68 is given to the other input of the subtracting means 87. The position control means 89 gives a command to the subtraction means 87 via the line 86 so that the output of the subtraction means 87 becomes zero, that is, the position of the valve element 66 of the pressure regulating valve 55 detected by the position detection means 68. A signal representing the amount of displacement for positioning at the position is derived and given to the pressure regulating valve driving means 67. The pressure regulating valve driving means 67 drives the valve body 66 of the pressure regulating valve 55 by stroke displacement in response to the output from the position control means 89.

Before the ventilation measurement, when the blow-out type wind tunnel 51 is completely stopped, the switch 84 is turned off and the switch 85 is turned on in the forced stop switching means 83. Therefore, the output of the fully closed position setting means 88 is
Is given to the subtraction means 87. Accordingly, the output of the position control means 89 causes the pressure regulating valve driving means 67 to drive the valve element 66 of the pressure regulating valve 55 to be seated on the valve seat 65, and the output of the position detecting means 68 in this seated state is given to the subtracting means 87. Thus, the position control deviation of the subtracting means 87 is zero.

Prior to the ventilation measurement, the forced stop switching means 8
In 3, the switch 84 is turned on and the switch 85 is turned off. Before the ventilation measurement, while the measurement is stopped, the switch 75 of the switching means 74 is shut off, and the switch 76 is in a conductive state. Therefore, the pressure control means 81
Is a pressure regulating valve 55 for the pressure P2 detected by the sensor 71 in the collecting cylinder 56 to become the atmospheric pressure P0 set by the atmospheric pressure setting means 73 and the pressure control deviation P12 of the subtracting means 78 to become zero. A signal representing the command position of the valve body 66 is derived and given to the subtraction means 87. Thus, the collecting cylinder 5
6 is maintained at the atmospheric pressure, and the pressure regulating valve 55 is in a fully closed state. Therefore, the first throat 57
The air does not flow back into the collecting cylinder 56 after passing through.

In the ventilation measurement, the switch 74 is switched from the state shown in FIG. 1 while the main valve 54 is open, the switch 75 is turned on, and the switch 76 is turned off. As a result, an output representing the predetermined ventilation measurement pressure P1 from the ventilation measurement pressure setting unit 72 is given to the subtraction unit 78 via the switch 75 and the line 77. Thereby, the pressure control means 81
Derives a signal indicating the position of the valve element 66 of the pressure regulating valve 55 so that the pressure P2 detected by the sensor 71 in the collecting cylinder 56 becomes equal to the ventilation measurement pressure P1. In this way, the high-pressure compressed air from the air storage tank 52 is supplied from the line 53 through the main valve 54 to the inside of the collecting cylinder 56 from the pressure regulating valve 55. The compressed air in the collecting cylinder 56 is rectified by the rectifying member 63, the pressure distribution is made uniform, and the compressed air is introduced from the first throat 57 into the measuring chamber 58 with a high-speed airflow of Mach 0.6 to 4.0. The ventilation of the model 64 is measured. The compressed air from the measurement chamber 58 is discharged to the atmosphere via the second throat section 59, the diffusion drum 61 and the silencer 62.

When the ventilation measurement is completed and the measurement is stopped, the switch 75 of the changeover switch 74 is turned off and the switch 76 is turned on. Therefore, the atmospheric pressure setting means 73
The output representing the atmospheric pressure P0 set by the above is supplied to the subtracting means 78 from the line 77 via the switch 76.
Therefore, the pressure control means 81 derives a signal indicating the position of the valve body 66 of the pressure regulating valve 55 so that the pressure P2 detected by the sensor 71 in the collecting cylinder 56 becomes equal to the atmospheric pressure P0. Thus, the pressure in the collecting cylinder 56 is always kept at the atmospheric pressure P0 when the measurement is stopped.
While the atmospheric pressure P0 is maintained, the switch 83 is switched to a state in which the airflow in the wind tunnel is stopped (after a timer has elapsed from the time of stop, or in a state where the atmospheric pressure is maintained and the pressure regulating valve is fully closed). Then, the switch 84 is turned off and the switch 85 is turned on. Thus, the state is returned to the state before the ventilation measurement. Therefore, there is no possibility that air flows backward from the measurement chamber 58 into the collecting cylinder 56 via the first throat portion 57. As a result, there is no risk that the rectifying member 63 in the collecting cylinder 56 will be deformed or damaged by the backflowing air, and since the air does not flow back in the measurement chamber 58, there is no possibility that the model 64 will be adversely affected. Also, because this backflow of air does not occur,
There is no danger that air from the outside will be sucked into the silencer 62, and therefore no noise in the low frequency range due to the backflow of air will occur.

FIG. 2 is a system diagram of another embodiment of the present invention. The embodiment of FIG. 2 is similar to the embodiment of FIG. 1 described above, and corresponding parts are denoted by the same reference numerals.
It should be noted that in this embodiment, a time rate-of-change limiter 92 is interposed in the line 77 between the switching means 74 and the subtracting means 78. The time rate-of-change limiter 92 functions to limit the pressure-decrease time-change rate of the setting of the collecting cylinder pressure to less than a predetermined value a.

FIG. 3 is a flowchart for explaining the operation of the time change rate limiter 92. The time change rate limiter 92 is realized by a processing circuit such as a microcomputer, for example. Step s1 to step s
When the input representing the set pressure P1 or P0 inputted from the switching means 74 to the time change rate limiter 92 and the output given to the subtraction means 78 from the time change rate limiter 92 are represented by Y, the following equation is obtained. It is determined whether 1 is established. t represents time.

[0047]

(Equation 1)

When the equation 1 is satisfied, the process proceeds from step s2 to step s3, where the output Y of the time change rate limiter 92 is output.
_n is derived as in Equation 2. _{Y n = Y n-1 +} a (Y n-1: previous output) ... (2)

Thus, the time change rate dX / dt of the input X given to the time change rate limiter 92 from the switching means 74.
Is less than the predetermined value a, the time change rate is suppressed to the predetermined value a to prevent a sudden change in the output Y. As a result, the pressure P2 detected by the sensor 71 in the collecting cylinder 56 is suppressed from changing at a large time change rate exceeding the predetermined value a. Therefore the collecting cylinder 56
In addition, backflow of air from the measurement chamber 58 and the first throat portion 57 can be prevented. Step s3 to step s
Then, the sequence goes to 4 to end a series of operations.

When Expression 1 is not satisfied in Step s2, that is, when Expression 3 is satisfied, the process proceeds to Step s5.

[0051]

(Equation 2)

The time change rate limiter 9 from the switching means 74
2 is a predetermined value a
When the value is less than the value, the output Y is derived in the step s5 as the expression 4 while keeping the input X. Y = X (4)

FIG. 4 is a diagram for explaining the operation of the time change rate limiter 92. As shown in FIG. 4A, before time t12, the pressure in the collecting cylinder 56 is maintained at the ventilation measurement pressure P1. Stop time t of ventilation measurement
2 and thereafter, as shown in FIG.
Is turned off, and the switch 76 is turned on. Therefore, after time t2, switching means 7
From 4, a signal indicating the atmospheric pressure P 0 set by the atmospheric pressure setting means 73 is derived from the line 77 as indicated by reference numeral 93 in FIG. Thus line 77
Changes rapidly from P1 to P0 around time t2.

In the present invention, the output Y of the time change rate limiter 92 is given by the function of the time change rate limiter 92.
As indicated by reference numeral 94 in FIG. 4B, the predetermined value a is a signal representing a command pressure that decreases with a lapse of time, for example, on a linear line with the lapse of time. Will be given. In one embodiment of the present invention, a = −5 kPa / sec may be selected.

In another embodiment of the present invention, the time change rate limiter 92 in FIG. 2 is connected between the switch 76 of the switching means 74 and the input of the time change rate limiter 92 as shown by reference numeral 92a. It may be configured to be interposed, or may be interposed as indicated by reference numeral 92b in the line 79 from which the output of the subtraction means 78 is derived, and in other embodiments of such an implementation , Line 7
7 is not provided with a time rate of change limiter 92, and the signal on its line 77 is provided directly to the subtraction means 78.

FIG. 5 is a system diagram of still another embodiment of the present invention. This embodiment is similar to the embodiment of FIGS. 1 to 4 described above, and corresponding parts are denoted by the same reference numerals. It should be noted that in this embodiment, the output of the ventilation measurement pressure setting means 72 is provided to the subtraction means 78 via the line 77. Switching means 96 is interposed between the pressure control means 81 and the subtraction means 87. The switching means 96 has a switch 97 for providing the output of the pressure control means 81 to the subtraction means 87 via a line 86, and another switch 98 for outputting the output of the fully closed position setting means 88. During the ventilation measurement, the switch 97 is turned on and the switch 98 is turned off. When the measurement is stopped, the switch 97 is turned off as shown in FIG. 5, and the switch 98 is turned on.

Between the switch 98 and the subtraction means 87,
The valve closing time change rate limiter 99 is interposed. The valve closing time change rate limiter 99 can be realized by a processing circuit such as a microcomputer.

FIG. 6 is a flowchart for explaining the operation of the valve closing time change rate limiter 99. Step r
The process proceeds from step 1 to step r2, where the signal representing the position θ0 of the fully closed position of the valve body 66 of the pressure regulating valve 55, and therefore the time change rate dX1 / dt of the input X1 of the valve closing time change rate limiter 99.
Is greater than or equal to a predetermined value b, that is,
Is determined.

[0059]

(Equation 3)

[0060] When the equation 5 is satisfied, with respect to the input X1 of the closing time variation rate limiter 99, when the output of the valve closing time variation rate limiter 99 and Y1 _n, the output Y of Formula 6
1 is derived. Y1 _n = Y1 _n-1 + b (6)

When the time change rate dX1 / dt of the input X1 of the valve closing time change rate limiter 99 is equal to or larger than the predetermined value b, the time change rate is limited to the predetermined value b. Thus, the process moves from step r3 to step r4, and a series of operations is completed.

When Expression 5 is not satisfied in Step r2, in Step r5, the valve closing time change rate limiter 99 operates so that the input X1 is directly used as the output Y1 as in Expression 8. Y1 = X1 (7)

FIG. 7 is a diagram for explaining the operation of the valve closing time change rate limiter 99. Before time t2,
It is assumed that the ventilation measurement operation is being performed, and the switch 97 of the switching means 96 has been turned off at time t12, and the switch 98 has been switched to the conducting state. At this time, the input to the valve closing time change rate limiter 99 is obtained from the output indicating the stroke position of the valve element 66 from the pressure control unit 81 indicating the opening degree θ1 of the pressure regulating valve 55 during the ventilation measurement, from the fully closed position setting unit 88. Is suddenly changed as indicated by reference numeral 101 to the output at the position of the fully closed opening θ0 represented by

When the time rate of change from the position θ1 to θ0 of the input X1 is equal to or greater than the predetermined value b, the valve closing time change rate limiter 99 outputs the command indicated by the reference numeral 102 in step r3. An output Y1 which is a value is derived. As a result, the opening of the pressure regulating valve 55 is gradually changed, and the pressure regulating valve 55 is fully closed.

In another embodiment of the present invention, the time change rates a and b of the time change rate limiter 92 and the valve closing time change rate limiter 99 are represented by reference numerals 94 and 7 in FIG.
As shown by reference numeral 102 in (2), although it is changed linearly in the first order, in another embodiment of the present invention, another curve 9 in FIGS. 4 (2) and 7 (2) is used.
4a, 102a and the like may be configured to change with time.

FIG. 8 is a system diagram of still another embodiment of the present invention. This embodiment is similar to the embodiment of FIGS. 1 to 7, and corresponding parts are denoted by the same reference numerals.
It should be noted that in this embodiment, the main valve 54
A connection pipe 104 is interposed between the pressure control valve 55 and the pressure control valve 55. One end of the connecting pipe 104 is connected to the pipe 53 between the main valve 54 and the pressure regulating valve 55 as described above. Connecting pipe 10
The other end of 4 is connected to collecting cylinder 56. In the middle of the connecting pipe 54, a negative pressure prevention valve 105 capable of controlling flow and fully closing
Is interposed.

The output of the position control means 89 is supplied to the pressure regulating valve driving means 67 and the time change rate limiter 10
6 given. The time change rate limiter 106 has a configuration similar to the time change rate limiter 99 in FIG. 2 described above, and when the value of the valve element 66 of the pressure regulating valve 55 is equal to or larger than a predetermined large time change rate value c, the time change rate With a predetermined value c
It works to suppress. The output of the time rate-of-change limiter 106 is provided to a driving unit 107 that opens and closes the negative pressure prevention valve 105 to adjust the aperture amount. In this way, when the ventilation measurement is stopped, the pressure regulating valve 55 moves at a large time rate of change and immediately enters the fully closed state, whereas the negative pressure prevention valve 105 moves with time from the time when the ventilation measurement is stopped. From the fully open state to the fully closed state, the opening is controlled at a time rate of change equal to or less than a predetermined value c to adjust the flow rate. As a result, the pressure in the collecting cylinder 56 does not suddenly change, and the flow of air flowing backward from the measuring chamber 58 for air in the collecting cylinder 56 to the collecting cylinder 56 via the first throat portion 57 can be prevented.

In each of the above embodiments, the values a, b, c
Is set to a gradual valve closing time change rate that is less than the maximum value of the valve closing time change rate of the opening degree of the pressure regulating valve 55, and thus it is possible to prevent the phenomenon that the backflow of air in the collecting cylinder 56 occurs as described above. it can.

FIG. 9 is a system diagram of still another embodiment of the present invention. The embodiment shown in FIG. 9 is similar to the embodiment shown in FIG. 8 described above, and corresponding portions are denoted by the same reference numerals. In particular, in this embodiment, the connecting pipe 104 includes not only the negative pressure prevention valve 105 but also the throttle 10.
8 is also interposed. As a result, when the ventilation measurement is stopped, the pressure in the collecting cylinder 56 is changed and reduced with a time change rate as small as possible to bring the pressure to the atmospheric pressure, and the above-described phenomenon of the backflow of air can be prevented. In the embodiment of FIG. 9, the time change rate limiter 1 used in FIG.
06 can be omitted.

FIG. 10 is a system diagram of another embodiment of the present invention. This embodiment is similar to the embodiment of FIGS. 1 to 9 and corresponding parts are denoted by the same reference numerals. In this embodiment, in particular, a check valve 109 is connected to the collecting cylinder 56. The check valve 109 introduces external air into the collecting cylinder 56 when the pressure of the air in the collecting cylinder 56 becomes a negative pressure lower than the atmospheric pressure. When the pressure in the collecting cylinder 56 is higher than the atmospheric pressure, the check valve 109 remains shut off.
Such a configuration shown in FIG. 10 is simple, and implementation of the present invention is easy.

The present invention can be implemented in connection with supersonic, subsonic, and transonic wind tunnels.

[0072]

According to the present invention, it is possible to prevent the pressure in the collecting cylinder from becoming negative, so that the flow of compressed air in the collecting cylinder is controlled by the pressure regulating valve from the collecting cylinder, the throat section, and the measuring section. Since the compressed air flows into the chamber in one direction, the backflow of the compressed air to the collecting cylinder does not occur, and the phenomenon of periodic repetition of the flow of air into and out of the collecting cylinder does not occur. As a result, the rectifying means provided in the collecting cylinder is not deformed and the life is not shortened, and there is no adverse effect on the model provided in the measuring chamber. Can be prevented. Advantageous Effects of Invention According to the present invention, it is possible to prevent a phenomenon that air periodically enters and exits when measurement of ventilation to the collecting cylinder is stopped.

[Brief description of the drawings]

FIG. 1 is a system diagram of an embodiment of the present invention.

FIG. 2 is a system diagram of another embodiment of the present invention.

FIG. 3 is a flowchart for explaining an operation of a time change rate limiter 92;

FIG. 4 is a diagram for explaining an operation of a time change rate limiter 92;

FIG. 5 is a system diagram of still another embodiment of the present invention.

FIG. 6 is a flowchart for explaining the operation of a valve closing time change rate limiter 99;

FIG. 7 is a diagram for explaining the operation of the valve closing time change rate limiter 99;

FIG. 8 is a system diagram of still another embodiment of the present invention.

FIG. 9 is a system diagram of still another embodiment of the present invention.

FIG. 10 is a system diagram of another embodiment of the present invention. In this embodiment,

FIG. 11 is a system diagram of the prior art.

FIG. 12 is a graph showing experimental results of the prior art shown in FIG. 11 by the present inventor.

[Explanation of symbols]

 REFERENCE SIGNS LIST 51 blow-out wind tunnel 52 air storage tank 53 conduit 54 main valve 55 pressure regulating valve 56 collecting cylinder 57 first throat section 58 measuring chamber 59 second throat section 61 diffusion drum 62 silencer 63 rectifying member 64 model 67 pressure regulator driving means 68 Position detection means 71 Sensor 72 Ventilation measurement pressure setting means 73 Atmospheric pressure setting means 80 Pressure regulating valve drive control means 81 Pressure control means 83 Forced stop switching means 88 Fully closed position setting means 89 Position control means 92, 106 Time change rate limiter Reference numeral 96 Switching means 99 Valve closing time change rate limiter 104 Connecting pipe 105 Negative pressure prevention valve 107 Driving means 108 Throttle 109 Check valve

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasunori Kusume 3-1, 1-1 Higashikawasaki-cho, Chuo-ku, Kobe-shi, Hyogo F-term in Kawasaki Heavy Industries, Ltd. Kobe factory (reference) 2G023 AA04 AB01 AC06

Claims (9)

[Claims] 1. A compressed air stored in an air storage tank is guided to a collecting cylinder from a pressure regulating valve having a variable opening, and a blow-out type wind provided with a throat portion and a measuring portion connected downstream of the collecting cylinder. A pressure sensor for detecting pressure in the collecting cylinder; a pressure setting means for measuring ventilation for setting a predetermined pressure for measuring ventilation in the collecting cylinder during ventilation measurement; In response to the output from the measurement pressure setting means, during ventilation measurement, the opening of the pressure regulating valve is controlled so that the pressure detected by the sensor becomes the pressure for ventilation measurement. Control means for controlling the opening degree to be smaller than the opening degree during ventilation measurement or for fully closing; and negative pressure preventing means for introducing air into the collecting cylinder so that the pressure in the collecting cylinder does not become negative when stopped. Pressure control of a blow-out type wind tunnel characterized by including Apparatus. 2. A compressed air stored in an air storage tank is guided to a collecting cylinder from a pressure regulating valve having a variable opening, and a blow-out type wind provided with a throat portion and a measuring portion connected downstream of the collecting cylinder. In the cylinder collecting cylinder pressure control device, a sensor 71 for detecting a pressure in the collecting cylinder, a ventilation measuring pressure setting means 72 for setting a predetermined ventilation measuring pressure in the collecting cylinder during the ventilation measurement, In response to the output of the atmospheric pressure setting means 73 to be set, the sensor, the pressure setting means for ventilation measurement, and the atmospheric pressure setting means, during the ventilation measurement, the detection pressure of the sensor becomes the pressure for ventilation measurement, and Means for controlling the opening of the pressure regulating valve so that the pressure inside the collecting cylinder is at atmospheric pressure when the collecting cylinder is stopped. 3. The control means includes: a switching means 74 for switching and outputting the outputs of the ventilation measurement pressure setting means and the atmospheric pressure setting means; and a subtracting means 7 for calculating a difference between outputs of the sensor and the switching means.
And a pressure regulating valve drive control means for controlling the opening of the pressure regulating valve so as to make the difference zero in response to the output of the subtraction means. Pressure control device for the collecting cylinder. 4. A compressed air stored in an air storage tank is guided to a collecting cylinder from a pressure regulating valve having a variable opening, and a blow-out type wind provided with a throat portion and a measuring portion connected downstream of the collecting cylinder. A pressure sensor for detecting pressure in the collecting cylinder, a pressure measuring means for setting a predetermined ventilation measuring pressure in the collecting cylinder during ventilation measurement, and an atmospheric pressure. Atmospheric pressure setting means, in response to the output of the sensor and the ventilation pressure setting means and the atmospheric pressure setting means, during ventilation measurement, so that the detection pressure of the sensor becomes the ventilation measurement pressure, and when the measurement is stopped, A blowing means characterized by including means for controlling the pressure in the collecting cylinder to a small value with a gradual decreasing time change rate a that is less than the maximum value of the pressure decreasing time change rate in the setting of the collecting cylinder pressure so that the pressure in the collecting cylinder becomes the atmospheric pressure. Collective cylinder pressure control device for wind tunnel. 5. The control means includes: a switching means for switching and outputting an output of the ventilation measurement pressure setting means and the atmospheric pressure setting means; a subtraction means for calculating a difference between outputs of the sensor and the switching means; A pressure regulating valve drive control means for controlling the opening of the pressure regulating valve so that the difference becomes zero in response to the output of the pressure control valve; The apparatus according to claim 4, further comprising a limiter (92) for limiting a rate of change (a) of the pressure drop time in setting the pressure to a value less than a predetermined value. 6. A compressed air stored in an air storage tank is guided to a collecting cylinder from a pressure regulating valve having a variable opening, and a blow-out type wind provided with a throat section and a measuring section connected downstream of the collecting cylinder. A sensor for detecting the pressure in the collecting cylinder, a ventilation setting pressure setting means for setting a predetermined ventilation measuring pressure in the collecting cylinder during the measurement of the ventilation, and a pressure regulating valve fully closed. The output of the full-close command signal generating means 88 for generating a full-close command signal, and the output of the full-close command signal generating means are controlled so that the pressure in the collecting cylinder does not become negative when the measurement is stopped. Valve closing time rate of change b that is less than the maximum value of the valve closing time rate of change, the valve closing time rate of change limiter 99 that changes with time, a sensor, a pressure setting means for ventilation measurement, and valve closing. In response to the output of the time rate of change limiter, The detection output of Sa controls the degree of opening of the pressure regulating valve so that the air flow measuring pressure,
A pressure regulating valve drive control means for controlling the opening of the pressure regulating valve in accordance with the output of the valve closing time change rate limiter when the measurement is stopped. 7. A compressed air stored in an air storage tank is guided to a collecting cylinder from a pressure regulating valve whose opening degree is variable via a pipeline, and a throat section and a measuring section are provided downstream of the collecting cylinder in series. A pressure sensor for detecting a pressure in the collecting cylinder; a pressure measuring means for setting a predetermined ventilation measuring pressure in the collecting cylinder during ventilation measurement; and a pipe. A connecting pipe 104 connecting the road and the collecting cylinder, a negative pressure prevention valve 105 interposed in the connecting pipe, a negative pressure preventing valve is fully closed during ventilation measurement, and the negative pressure preventing valve is opened when measurement is stopped. A control means for introducing compressed air in the pipeline into the collecting cylinder so that the pressure in the collecting cylinder does not become negative pressure. 8. The apparatus according to claim 7, further comprising a throttle (108) interposed in the connecting pipe. 9. The check valve according to claim 1, wherein the negative pressure preventing means is a check valve provided in the collecting cylinder and for introducing outside air when the pressure in the collecting cylinder becomes negative. Collective cylinder pressure control device for blow-out type wind tunnel.