CN109738150B - Low-speed backflow wind tunnel small wind speed precision control method - Google Patents
Low-speed backflow wind tunnel small wind speed precision control method Download PDFInfo
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Abstract
The low-speed backflow wind tunnel small wind speed precision control method can improve the low-speed backflow wind tunnel small wind speed control precision without changing the original low-speed backflow wind tunnel flow field parameters, and effectively expands the low-speed backflow wind tunnel experiment range. The control method comprises the following steps: processing an air vent on the wall of the stable section, and mounting sealing strips on two sides of the air vent; manufacturing an air discharge quantity control sleeve and installing a guide rail and a rack; erecting a stepping motor, installing a gear, and connecting a control end of the stepping motor into a computer; a wind speed probe is installed in the wind tunnel test section and is connected to a computer through a micro differential pressure sensor; the air vent is isolated from the outside through the air vent control sleeve; starting the wind tunnel, measuring the actual wind speed in the wind tunnel test section, comparing the actual wind speed with the set wind speed, communicating the air release hole with the outside, increasing the communication area at a constant speed, gradually reducing the actual wind speed in the wind tunnel test section, and stopping the stepping motor immediately when the actual wind speed in the wind tunnel test section reaches the set wind speed.
Description
Technical Field
The invention belongs to the technical field of wind tunnel experiments, and particularly relates to a low-speed backflow wind tunnel small wind speed precision control method.
Background
The wind tunnel is a pipeline-shaped experimental device, can generate and control airflow in a manual mode, is used for simulating the flowing condition of air around an aircraft or an entity, and can measure the action effect of the airflow on the entity and observe physical phenomena. Wind tunnel experiments are indispensable components in aircraft development work, play an important role in the research and development of aviation and aerospace engineering, and are indispensable in the fields of transportation, building construction, wind energy utilization and the like along with the development of industrial aerodynamics. In the wind tunnel experiment, the model or the object is often fixed in the wind tunnel to be repeatedly blown, experimental data is obtained through a measurement and control instrument and equipment, and in order to ensure that the experimental result is accurate, the flow in the experiment must be similar to the actual flow state, namely the requirement of the similarity law must be met. However, due to the limitations of wind tunnel size and power, it is difficult to simulate all similar parameters simultaneously in a wind tunnel, and it is common to select some similar parameters that have the greatest influence for simulation according to the subject to be studied. In addition, the flow field quality of the wind tunnel test section, such as the uniformity of air flow velocity distribution, the size of the deviation of the average air flow direction from the axis of the wind tunnel, the pressure gradient along the axis of the wind tunnel, the uniformity of section temperature distribution, the turbulence of the air flow and the like, must meet certain standards, and the primary premise for realizing the flow field quality is the wind tunnel wind speed control accuracy.
According to the different speed ranges of the wind tunnel test sections, the wind tunnel test sections can be divided into a low-speed wind tunnel (Ma is less than or equal to 0.3), a subsonic wind tunnel (Ma is less than or equal to 0.3 and less than or equal to 0.8), a transonic wind tunnel (Ma is less than or equal to 0.8 and less than or equal to 1.4), a supersonic wind tunnel (Ma is less than or equal to 1.5 and less than or equal to 5.0) and a hypersonic wind. The low-speed wind tunnel can be divided into a direct-current wind tunnel and a return wind tunnel, and the return wind tunnel is widely applied due to low power and good flow field performance.
Taking a low-speed backflow wind tunnel as an example, the speed is generally below 100m/s, and the currently applied control means mainly comprises frequency conversion speed regulation control and direct current speed regulation control. Due to the development of the current frequency conversion technology, the frequency conversion speed regulation is widely applied to wind tunnel control. The power system fan of the low-speed backflow wind tunnel is driven by an alternating-current asynchronous motor, and the variable-frequency speed regulation controls the rotating speed of the motor by changing the input frequency of the alternating-current asynchronous motor, so that the wind speed of a wind tunnel test section is controlled. The low-speed backflow wind tunnel controls the wind speed of the test section by controlling the rotating speed of the asynchronous motor, and within the control range of 0-100 m/s, the requirement that each experimental wind speed can meet the precision requirement is difficult to meet.
Because some experiments must be carried out under a small wind speed, such as dust diffusion and smoke diffusion in the aspect of environmental pollution, the wind speed is generally required to be below 1m/s or even lower in the experiments. If only from the perspective of controlling the rotating speed of the motor, the control precision of the small wind speed is difficult to meet, and some people try to increase the loss of the wind tunnel by inserting more damping nets so as to improve the control precision of the small wind speed, but the actual result is not ideal, the wind speed cannot be continuously adjusted, and the adjustment range is limited.
The traditional wind speed control part of the low-speed backflow wind tunnel mainly comprises a computer, an acquisition card, a photoelectric isolator, a frequency converter, a fan motor, a differential pressure sensor, a signal conditioner, a wind speed sensor and a transmitter, wherein an execution process is to input a set wind speed value, the computer adopts a PID algorithm to calculate a corresponding output digital signal according to the set wind speed, the digital signal is converted into an analog signal quantity through a D/A (digital/analog) digital-to-analog converter until the acquisition card sends an analog voltage signal, the analog voltage signal enters the photoelectric isolator, a low-voltage signal is isolated from a high-voltage signal through the photoelectric isolator, the high-voltage signal is prevented from entering the computer, the high-voltage signal directly enters the frequency converter through the photoelectric isolator, and the frequency converter correspondingly changes the power supply frequency of the fan motor according to a control signal so as to change the rotating speed of the motor and. Meanwhile, the wind speed sensor and the transmitter continuously acquire wind speed differential pressure signals and send the signals back to the computer, the computer converts the voltage signals into wind speed, simultaneously compares the measured wind speed with the set wind speed, calculates the deviation, calculates the voltage to be accumulated under the corresponding deviation by calling a PID algorithm, outputs new analog voltage signals again by combining the output voltage, and continuously repeats the process until the wind speed value reaches the set wind speed value.
The wind speed control mode is very suitable for controlling the precision of large wind speed, but is not suitable for controlling the precision of small wind speed any more, the precision control error is large, and when the actual wind speed of small wind speed is lower than 3m/s, the wind speed control system can not be started even. Therefore, a method for improving the control accuracy of the low wind speed in the low-speed backflow wind tunnel is needed.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides the low-speed backflow wind tunnel small wind speed precision control method, which can improve the small wind speed control precision of the low-speed backflow wind tunnel without changing the flow field parameters of the original low-speed backflow wind tunnel and effectively expand the experimental range of the low-speed backflow wind tunnel.
In order to achieve the purpose, the invention adopts the following technical scheme: a low-speed backflow wind tunnel small wind speed precision control method comprises the following steps:
the method comprises the following steps: firstly, reforming the wall of the stable section hole, and processing four air vents on the wall of the stable section hole, wherein the four air vents are uniformly distributed on the wall of the stable section hole along the circumferential direction;
step two: processing a sealing groove on the outer surface of the hole wall of the stable section at two sides of the air vent, and embedding a sealing strip in the sealing groove;
step three: manufacturing a deflation amount control sleeve, sleeving the deflation amount control sleeve on the outer side of the hole wall of the stabilization section, arranging a plurality of guide rails between the inner surface of the deflation amount control sleeve and the outer surface of the hole wall of the stabilization section, wherein the guide rails are fixedly connected with the outer surface of the hole wall of the stabilization section, and the deflation amount control sleeve can move along the guide rails;
step four: a rack is arranged on the outer surface of the air bleeding amount control sleeve, and the rack is ensured to be parallel to the guide rail;
step five: a step motor is fixedly erected above the rack, a gear is arranged on a motor shaft of the step motor to ensure that the gear is meshed with the rack, and then a control end of the step motor is connected with a computer of the wind tunnel system;
step six: installing a wind speed probe in the wind tunnel test section, connecting a data connector of the wind speed probe with a computer through a micro-pressure difference sensor, then installing a damping net and a honeycomb device in the wall of the stable section, and finishing the transformation work of the low-speed backflow wind tunnel;
step seven: before the wind tunnel is started, the step motor is controlled to act, the gear and the rack are meshed for transmission, so that the air discharge amount control sleeve completely covers the sealing strips on the two sides of the air discharge hole, and the air discharge hole is completely isolated from the outside;
step eight: the wind tunnel is started, a wind speed probe is used for collecting a differential pressure signal of actual wind speed in a wind tunnel test section, a micro differential pressure sensor is used for processing the differential pressure signal, the processed differential pressure signal is directly transmitted to a computer, the computer can compare the differential pressure signal with set wind speed, meanwhile, the computer sends a control instruction to a stepping motor, the stepping motor drives an air bleeding amount control sleeve to move, so that an air bleeding hole is communicated with the outside, the communication area of the air bleeding hole and the outside is increased at a constant speed, the actual wind speed in the wind tunnel test section is gradually reduced under the air bleeding effect, and when the computer judges that the actual wind speed in the wind tunnel test section reaches the set wind speed, the stepping motor is immediately stopped, and the communication area of the air bleeding hole and the outside is kept constant.
The invention has the beneficial effects that:
the low-speed backflow wind tunnel small wind speed precision control method can improve the small wind speed control precision of the low-speed backflow wind tunnel without changing the flow field parameters of the original low-speed backflow wind tunnel, and effectively expands the experimental range of the low-speed backflow wind tunnel.
Drawings
FIG. 1 is a schematic structural diagram of a low-speed backflow wind tunnel (before small wind speed precision control) after reconstruction is completed;
3 FIG. 3 2 3 is 3 a 3 cross 3- 3 sectional 3 view 3 taken 3 along 3 line 3 A 3- 3 A 3 of 3 FIG. 3 1 3; 3
FIG. 3 is a cross-sectional view taken along line B-B of FIG. 1;
FIG. 4 is a schematic structural diagram of a low-speed backflow wind tunnel (in small wind speed precision control) after the reconstruction is completed;
in the figure, 1 is a stable section hole wall, 2 is an air vent, 3 is a sealing strip, 4 is an air vent control sleeve, 5 is a guide rail, 6 is a rack, 7 is a stepping motor, 8 is a gear, 9 is a wind tunnel test section, 10 is a wind speed probe, 11 is a micro differential pressure sensor, 12 is a damping net, 13 is a honeycomb device, and 14 is a computer.
Detailed Description
The invention is described in further detail below with reference to the figures and the specific embodiments.
A low-speed backflow wind tunnel small wind speed precision control method comprises the following steps:
the method comprises the following steps: firstly, reforming a stable section hole wall 1, processing four air vents 2 on the stable section hole wall 1, and uniformly distributing the four air vents 2 on the stable section hole wall 1 along the circumferential direction;
step two: processing a sealing groove on the outer surface of the stable section hole wall 1 at two sides of the air vent 2, and then embedding a sealing strip 3 in the sealing groove;
step three: manufacturing an air discharge quantity control sleeve 4, sleeving the air discharge quantity control sleeve 4 on the outer side of the stable section hole wall 1, arranging a plurality of guide rails 5 between the inner surface of the air discharge quantity control sleeve 4 and the outer surface of the stable section hole wall 1, fixedly connecting the guide rails 5 with the outer surface of the stable section hole wall 1, and enabling the air discharge quantity control sleeve 4 to move along the guide rails 5;
step four: a rack 6 is arranged on the outer surface of the air bleeding amount control sleeve 4, and the rack 6 is ensured to be parallel to the guide rail 5;
step five: a step motor 7 is fixedly erected above the rack 6, a gear 8 is arranged on a motor shaft of the step motor 7 to ensure that the gear 8 is meshed with the rack 6, and then the control end of the step motor 7 is connected with a computer 14 of the wind tunnel system;
step six: installing a wind speed probe 10 in a wind tunnel test section 9, connecting a data connector of the wind speed probe 10 with a computer 8 through a micro-pressure difference sensor 11, then installing a damping net 12 and a honeycomb device 13 in a stable section tunnel wall 1, finishing the transformation work of the low-speed backflow wind tunnel, and obtaining the transformed effect as shown in figures 1-3;
step seven: before the wind tunnel is started, the step motor 7 is controlled to act, the gear 8 is meshed with the rack 6 for transmission, so that the air discharge amount control sleeve 4 completely covers the sealing strips 3 on two sides of the air discharge hole 2, and the air discharge hole 2 is completely isolated from the outside;
step eight: starting the wind tunnel, acquiring a differential pressure signal of an actual wind speed in the wind tunnel test section 9 through a wind speed probe 10, processing the differential pressure signal by a micro differential pressure sensor 11, directly transmitting the processed differential pressure signal to a computer 14, comparing the differential pressure signal with a set wind speed by the computer 14, sending a control instruction to a stepping motor 7 by the computer 14, driving an air discharge control sleeve 4 to move by the stepping motor 7, so that an air discharge hole 2 is communicated with the outside, the communication area of the air discharge hole 2 and the outside is increased at a constant speed, the actual wind speed in the wind tunnel test section 9 is gradually reduced under the air discharge effect, and when the computer 14 judges that the actual wind speed in the wind tunnel test section 9 reaches the set wind speed, immediately stopping the stepping motor 7, so that the communication area of the air discharge hole 2 and the outside is kept constant, as shown in fig. 4.
In order to better illustrate that the invention can effectively improve the small wind speed control precision of the low-speed backflow wind tunnel, the low-speed backflow wind tunnel is actually transformed, the cross-sectional dimension of the stable section tunnel wall 1 of the low-speed backflow wind tunnel is 800mm multiplied by 800mm, the length of the stable section tunnel wall 1 is 1200mm, the cross-sectional dimension of the wind tunnel test section 9 is 400mm multiplied by 400mm, the length of the wind tunnel test section 9 is 800mm, and the size of the air release hole 2 is 500mm multiplied by 200 mm; the micro differential pressure sensor 11 has a measurement range of 25pa and a full-scale accuracy of 0.0005 pa.
Taking a dust diffusion experiment as an example, the set wind speed required by the experiment is 0.8m/s, the actual wind speed in the wind tunnel test section 9 is 3m/s after the wind tunnel is started, and the wind speed is smoothly adjusted to 0.8m/s after the wind speed is adjusted by the method, and the wind speed control precision reaches +/-0.15 m/s, so that the set target of the invention is completely realized.
The embodiments are not intended to limit the scope of the present invention, and all equivalent implementations or modifications without departing from the scope of the present invention are intended to be included in the scope of the present invention.
Claims (1)
1. A low-speed backflow wind tunnel small wind speed precision control method is characterized by comprising the following steps:
the method comprises the following steps: firstly, reforming the wall of the stable section hole, and processing four air vents on the wall of the stable section hole, wherein the four air vents are uniformly distributed on the wall of the stable section hole along the circumferential direction;
step two: processing a sealing groove on the outer surface of the hole wall of the stable section at two sides of the air vent, and embedding a sealing strip in the sealing groove;
step three: manufacturing a deflation amount control sleeve, sleeving the deflation amount control sleeve on the outer side of the hole wall of the stabilization section, arranging a plurality of guide rails between the inner surface of the deflation amount control sleeve and the outer surface of the hole wall of the stabilization section, wherein the guide rails are fixedly connected with the outer surface of the hole wall of the stabilization section, and the deflation amount control sleeve can move along the guide rails;
step four: a rack is arranged on the outer surface of the air bleeding amount control sleeve, and the rack is ensured to be parallel to the guide rail;
step five: a step motor is fixedly erected above the rack, a gear is arranged on a motor shaft of the step motor to ensure that the gear is meshed with the rack, and then a control end of the step motor is connected with a computer of the wind tunnel system;
step six: installing a wind speed probe in the wind tunnel test section, connecting a data connector of the wind speed probe with a computer through a micro-pressure difference sensor, then installing a damping net and a honeycomb device in the wall of the stable section, and finishing the transformation work of the low-speed backflow wind tunnel;
step seven: before the wind tunnel is started, the step motor is controlled to act, the gear and the rack are meshed for transmission, so that the air discharge amount control sleeve completely covers the sealing strips on the two sides of the air discharge hole, and the air discharge hole is completely isolated from the outside;
step eight: the wind tunnel is started, a wind speed probe is used for collecting a differential pressure signal of actual wind speed in a wind tunnel test section, a micro differential pressure sensor is used for processing the differential pressure signal, the processed differential pressure signal is directly transmitted to a computer, the computer can compare the differential pressure signal with set wind speed, meanwhile, the computer sends a control instruction to a stepping motor, the stepping motor drives an air bleeding amount control sleeve to move, so that an air bleeding hole is communicated with the outside, the communication area of the air bleeding hole and the outside is increased at a constant speed, the actual wind speed in the wind tunnel test section is gradually reduced under the air bleeding effect, and when the computer judges that the actual wind speed in the wind tunnel test section reaches the set wind speed, the stepping motor is immediately stopped, and the communication area of the air bleeding hole and the outside is kept constant.
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0619303B2 (en) * | 1989-05-27 | 1994-03-16 | 川崎重工業株式会社 | Wind tunnel wind speed controller |
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| JPH09113404A (en) * | 1995-10-17 | 1997-05-02 | Mitsubishi Heavy Ind Ltd | Breeze-velocity control apparatus |
| JPH10123010A (en) * | 1996-10-24 | 1998-05-15 | Mitsubishi Heavy Ind Ltd | Wind velocity controller for wind tunnel |
| CN100538307C (en) * | 2007-01-16 | 2009-09-09 | 中国计量学院 | A kind of wind tunnel calibration method for large flow gas pipeline averaging velocity tube flowmeter |
| CN105572422B (en) * | 2014-10-13 | 2019-04-09 | 辽宁省计量科学研究院 | High-performance wind speed measurement system |
| CN205229186U (en) * | 2015-12-17 | 2016-05-11 | 刘智勇 | Wind speed intelligent control device |
| CN205593725U (en) * | 2016-04-18 | 2016-09-21 | 武汉科技大学 | Test air tunnel |
| CN109243263A (en) * | 2018-08-30 | 2019-01-18 | 北京航空航天大学 | A kind of Table top type DC low-speed wind-tunnel of teaching demonstration and experiment |
| CN109115448A (en) * | 2018-09-30 | 2019-01-01 | 天津中德应用技术大学 | A kind of TT&C system suitable for small-sized wind tunnel |
| CN109115449A (en) * | 2018-10-19 | 2019-01-01 | 天津中德应用技术大学 | A kind of intelligent Wind Speed regulator control system suitable for small-sized wind tunnel |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH0619303B2 (en) * | 1989-05-27 | 1994-03-16 | 川崎重工業株式会社 | Wind tunnel wind speed controller |
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