CN102426091B - Protective device of dynamic pressure sensor used in wind tunnel air inlet experiment - Google Patents
Protective device of dynamic pressure sensor used in wind tunnel air inlet experiment Download PDFInfo
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- CN102426091B CN102426091B CN 201110310432 CN201110310432A CN102426091B CN 102426091 B CN102426091 B CN 102426091B CN 201110310432 CN201110310432 CN 201110310432 CN 201110310432 A CN201110310432 A CN 201110310432A CN 102426091 B CN102426091 B CN 102426091B
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Abstract
The invention discloses a protective device of a dynamic pressure sensor used in a wind tunnel air inlet experiment. A pressure monitoring sensor monitors a dynamic pressure airflow change rate in an air inlet. After an amplified pressure airflow change rate signal exceeds a set parameter, an air inlet power supply is turned off. N dynamic pressure sensors collect dynamic pressure data of the air inlet. The data is amplified and is sent to an industrial controller through a VXI data acquisition system so as to obtain a distortion index needed by the air inlet experiment. A vibration monitoring sensor measures dynamic airflow vibration change in the air inlet. After the amplified dynamic airflow vibration signal exceeds the set parameter, the air inlet power supply is turned off. By using the protective device of the invention, the dynamic pressure sensor can be protected so that economic losses can be reduced. Folding installation can be achieved and usage is convenient.
Description
Technical field
The present invention relates to survey control technology field, especially a kind of protective device of pressure transducer.
Background technology
The wind-tunnel air inlet experiment is completed measurement to distortion index with dynamic pressure transducer.Very difficult and cost is high due to the technology of making dynamic pressure transducer, so the dynamic pressure transducer price is very expensive.The sill Key experiments analytical equipment of air inlet/engine Compatibility Evaluation as " dynamic pressure distortion high-speed data acquisition and real time storage and processing system ", thought a kind of technical sophistication, the system that involves great expense abroad, U.S. FAT company once offered 3,000,000 dollars, and wherein the dynamic pressure transducer proportion is very large.Do not wait according to its unit price of difference unit from thousands of to tens thousand of of the indexs such as the measuring accuracy of dynamic pressure transducer, range, frequency response, quality.The measurement of inlet distortion index is tested at every turn to be needed with the dynamic pressure transducer more than 10, and the quality of the dynamic pressure data that measure can directly affect experimental result, so dynamic pressure transducer is most important.Need to select as requested range and the precision of dynamic pressure transducer during general air inlet experiment.The too large measuring accuracy of measurement range selection does not reach and requires data inaccurate, and selected range is moderate can effectively be obtained to measure dynamic data but be very easy to damage dynamic pressure transducer, changes again very trouble after damaging.Studying carefully the flimsy reason of its appearance is when carrying out air inlet experiment because of wind-tunnel, in air intake duct, dynamic pressure is arranged not only but also have dynamic vibration and dynamic impulsion, air-flow is very complicated, the flow field is extremely unstable, cause the damage of dynamic pressure transducer, wherein vibrated and impacted the factor that causes larger.Technology does not have good way effectively to protect dynamic pressure transducer now.The parameters such as transducer range and precision are selected to avoid the damage of dynamic pressure transducer with experiment experience and experimental data to air intake duct exactly.Again measurement quality and experimental data are played conclusive effect because the price of dynamic pressure transducer is very expensive.Extremely important with regard to what show to the protection of dynamic pressure transducer like this.For this reason " vibration with impact " published " application of traveling wave rod pressure gages in the explosion wave load test " literary composition in April, 2007 and relate to and use traveling wave rod pressure gages to solve the problems such as the low and easy damage of common sensor frequency response under the high-frequency pressure pulse.This method ultimate principle can not be used for the wind-tunnel air inlet experiment, in addition, and because the protector volume can't be arranged in air intake duct greatly." Oil ﹠ Gas Storage " 01 periodical in 1999 is stepped on " dynamic perfromance of Shuttle-type Rupturing Protection Valve of Pipeline "; Shuttle-type Rupturing Protection Valve of Pipeline is used for when pipe leakage reaches the protection value of setting, can block rapidly to carry to prevent to leak and just dynamic perfromance carried out experimental study.Above two kinds of methods can not be applied in the wind-tunnel air inlet experiment and effectively protect dynamic pressure transducer and prevent from damaging.
Summary of the invention
the deficiency that can't protect dynamic pressure transducer and prevent from damaging in the wind-tunnel air inlet experiment in order to overcome prior art, the invention provides a kind of protective device of dynamic pressure sensor used in wind tunnel air inlet experiment, according to the dynamic pickup instructions, the parameter of pressure monitoring parameter setting device and the parameter that experiment experience arranges the vibration monitoring parameter setting device are set, the parameter value rear drive stop that force value in air intake duct or vibration values overpressure monitoring parameter arrange device or the setting of vibration monitoring parameter setting device cuts off rapidly the air intake duct power supply, thereby effectively protect dynamic pressure transducer.
Main thought of the present invention is: dynamic pressure transducer, PVDF pressure transducer and PVDF vibration transducer can be used for measuring the variation of the interior dynamic pressure of air intake duct and vibration.Table 1 is the various performance comparison of dynamic pressure transducer, PVDF pressure transducer, PVDF vibration transducer, obtains thus conclusion; 1, because the PVDF material sensors is fast to the jump signal reaction, can reflect in advance the rate of change of air-flow in air intake duct.2, the PVDF material sensors have highly sensitive, very frivolous, shock-resistant, Hz-KHz is wide, cost is low, non-damageable characteristics.3, because measurement dynamic range and frequency range are large, PVDF need not change the range of pressure monitoring sensor and vibration transducer.4, dynamic pressure transducer measurement precision is high; can be used for measurement data; and that PVDF pressure transducer, PVDF vibration transducer are measured precision is low; can be used to protect pressure transducer, the content of parameter (dynamic pressure maximal value, dynamic pressure maximal value time delay, frequency response) that the pressure monitoring parameter setting device is set according to the instructions of dynamic pickup is put into the pressure monitoring parameter setting device as parameter value.The parameter that the vibration monitoring parameter setting device is set according to experiment experience obtains content of parameter (maximum vibration frequency, maximum vibration frequency time delay, vibration displacement) and puts into the vibration monitoring parameter setting device as parameter value.After the pressure overpressure monitoring parameter in air intake duct arranged the parameter of device or dynamic vibration parameter and surpasses the parameter of vibration monitoring parameter setting device, pressure stop or vibration stop cut off rapidly air intake duct
Table 1
Power supply, dynamic pressure transducer is played a protective role.
The technical scheme that technical solution problem of the present invention adopts is: comprise pressure monitoring sensor, charge amplifier, pressure monitoring parameter setting device, pressure stop, a N dynamic pressure transducer, a N programmable amplifier, VXI data acquisition system (DAS), Industrial Control Computer, air intake duct power supply, vibration monitoring sensor, isolated amplifier, vibration monitoring parameter setting device and vibration stop, 1＜=N＜=300.dynamic pressure variations in flow rate in pressure monitoring sensor monitoring air intake duct, output pressure variations in flow rate signal to charge amplifier amplifies, forced draft rate of change signal overpressure monitoring parameter after amplifying turn-offs the air intake duct power supply by the pressure stop after the parameter that device arranges is set, N dynamic pressure transducer gathers the dynamic pressure data of air intake duct, transfer to the VXI data acquisition system (DAS) after amplifying through N programmable amplifier respectively, VXI data acquisition system (DAS) collection dynamic pressure data are sent into Industrial Control Computer again and are obtained the needed distortion index of air inlet experiment by calculating the distortion index method, in vibration monitoring sensor measurement air intake duct, the dynamic air current vibration changes, output dynamic air current vibration signal to isolated amplifier amplifies, turn-off the air intake duct power supply by the vibration stop after the parameter that the dynamic air current vibration signal after amplification arranges over the vibration monitoring parameter setting device, Industrial Control Computer arranges the parameter of pressure monitoring parameter setting device according to the dynamic pressure transducer range in the dynamic pressure transducer instructions, the parameter of vibration monitoring parameter setting device is set according to the actual demand of experiment.
Described pressure monitoring sensor adopts the PVDF material pressure transducer.
Described vibration monitoring sensor adopts PVDF material vibrating sensor.
Described pressure monitoring sensor, dynamic pressure transducer and vibration monitoring installation of sensors and evenly distribute by circumferencial direction on the same xsect of air intake duct, connect the earth after above-mentioned three kinds of sensor mask.
The content of parameter of described pressure monitoring parameter setting device is followed following requirement by dynamic pressure transducer instructions:
1, dynamic pressure maximal value＜=dynamic pressure transducer pressure range * 1.414.
2, dynamic pressure maximal value time delay＜=0.1 S ~ 0.5S.
3, frequency response＜=1/2 ~ 1/10* dynamic pressure transducer natural frequency.
Three parameter values are put into the pressure monitoring parameter setting device, turn-off later on the air intake duct power supply when the parameter in air intake duct surpasses setting value.
The content of parameter of described vibration monitoring parameter setting device is followed experiment experience by following requirement:
1, the maximum vibration frequency is got 0.5 Hz ~ 7Hz.
2, maximum vibration frequency time delay＜=0.3S ~ 1S.
3, vibration displacement＜=400 um ~ 1000um.
Three parameter values are put into the vibration monitoring parameter setting device, turn-off later on the air intake duct power supply when the parameter in air intake duct surpasses setting value.
The invention has the beneficial effects as follows: the present invention can provide the device of protection dynamic pressure transducer; the parameter value rear drive stop that force value in air intake duct or vibration values overpressure monitoring parameter arrange device or the setting of vibration monitoring parameter setting device cuts off rapidly the air intake duct power supply, thereby the effect of playing the protection dynamic pressure transducer reduces economic loss.The cost of material is low to utilize PVDF, but collapsible installation, the convenient characteristics of using the also various pressure experiments of widespread use or vibration experiment.
The present invention is further described below in conjunction with drawings and Examples.
Description of drawings
Fig. 1 is device schematic diagram of the present invention.
Embodiment
Fig. 1 is device schematic diagram of the present invention, in pressure monitoring sensor monitoring air intake duct, dynamic pressure variations in flow rate is that the charge amplifier of M193802 amplifies the dynamic air current pressure change rate to model, and it is to be LSM 020.2 by model after the parameter of pressure monitoring parameter setting device of YPK-38 the pressure stop turn-offs the air intake duct power supply that the signal after amplifying surpasses model.Choose N=15, the dynamic pressure transducer 1 that to adopt 15 models are XCS-9301-5D ..., dynamic pressure transducer 15 gather air intake ducts dynamic data respectively through by model be the TS-2000 plate multichannel programmable amplifier 1 ..., programmable amplifier 15 with dynamic data amplify after to model be the VXI data acquisition system (DAS) parallel acquisition dynamic data of VXI16015S.It is that the Industrial Control Computer of IPC610 calculates the needed distortion index of air inlet experiment result that the VXI data acquisition system (DAS) is sent dynamic data into model.The isolated amplifier that the dynamic air current vibration signal is AD204 by model in vibration monitoring sensor measurement air intake duct amplifies vibration signal, and it is to be G37 by model after the parameter of vibration monitoring parameter setting device setting of JYHK-HZD-B-5 the vibration stop turn-offs the air intake duct power supply that the signal after amplifying surpasses model.The parameter of pressure monitoring parameter setting device is set according to the dynamic pressure transducer range in the dynamic pressure transducer instructions with the Industrial Control Computer Industrial Control Computer, and Industrial Control Computer arranges the parameter of vibration monitoring parameter setting device according to experiment experience.
The material of selecting pressure monitoring sensor is the PVDF material pressure transducer, and its size is Φ 50mm, thick 350 μ m.
The material of selecting the vibration monitoring sensor is PVDF material vibrating sensor, and size is: long 18mm, wide 18mm, thick 170 μ m.
Select a pressure monitoring sensor, 15 dynamic pressure transducers, a vibration monitoring installation of sensors evenly to distribute by circumferencial direction on the xsect of Φ 350mm, then will connect the earth after sensor mask.
The dynamic pressure transducer range arranges the content of parameter of pressure monitoring parameter setting device:
When the range of dynamic pressure transducer=5PSI;
1, dynamic pressure maximal value=7PSI.
2, dynamic pressure maximal value time delay=0.1S.
3, frequency response=100KHZ.
Three parameter values are put into the pressure monitoring parameter setting device, turn-off later on the air intake duct power supply when the parameter in air intake duct surpasses setting value.
The content of parameter of vibration monitoring parameter setting device is set:
1, the maximum vibration frequency is got 0.5HZ.
2, maximum vibration frequency time delay=0.3S.
3, vibration displacement=400um.
Three parameter values are put into the vibration monitoring parameter setting device, turn-off later on the air intake duct power supply when the parameter in air intake duct surpasses setting value.
Illustrate: when the range of dynamic pressure transducer=can get the higher limit in parameters during 100PSI.Work as 100PSI〉range 〉=10PSI can get the intermediate value in parameters, work as 10PSI〉range can get lower limit in parameters (parameters comprises three parameter values of pressure monitoring parameter setting device and three parameter values of vibration monitoring parameter setting device).
When above-mentioned parameter N is set to the number such as 1,90,300, only the density that distributes etc. is changed and get final product, all can realize same function, number is more, measurement more accurate.
The present invention compared with prior art has following significant advantage:
1) because pressure monitoring sensor is fast to dynamic pressure variations in flow rate reaction, in time cuts off the electricity supply when occurring super dynamic dynamic pressure maximal value, dynamic pressure maximal value time delay, frequency response and maximum vibration frequency, maximum vibration frequency time delay, vibration displacement in air intake duct dynamic pressure transducer is effectively protected.
2) measure the dynamic pressure range due to PVDF and vibration frequency range is large, price quite cheaply and not can be damaged, so need not change pressure monitoring sensor and vibration transducer.
3) can select the high-acruracy survey of carrying out distortion index near the dynamic pressure transducer of maximum data range in experiment as far as possible, make measurement data more near actual conditions.
4) the cost of material is low for PVDF, collapsible installing and using.
Working routine is: 1, install: with pressure monitoring sensor, dynamic pressure transducer 1 ... dynamic pressure transducer N, vibration monitoring installation of sensors evenly distribute by circumferencial direction on xsect, then will connect the earth after sensor mask.2, with Industrial Control Computer, the parameter of pressure monitoring parameter setting device is set respectively and the parameter of vibration monitoring parameter setting device is set, the parameter (dynamic pressure maximal value, dynamic pressure maximal value time delay, frequency response) of pressure monitoring parameter setting device is set according to the instructions of dynamic pickup, the parameter (maximum vibration frequency, maximum vibration frequency time delay, vibration displacement) of vibration monitoring parameter setting device is set according to experiment experience.3, experiment: the dynamic pressure air-flow of air intake duct is increased, in pressure monitoring sensor monitoring air intake duct, dynamic pressure variations in flow rate to charge amplifier amplifies the dynamic air current pressure change rate, and the pressure change rate signal overpressure monitoring parameter after amplifying automatically shuts down the air intake duct power supply by the pressure stop after the parameter of device setting is set.The interior dynamic air current vibration signal of vibration monitoring sensor measurement air intake duct changes and by isolated amplifier, vibration signal is amplified, and turn-offs the air intake duct power supply by vibrating stop after the parameter that the dynamic air current vibration signal after amplification arranges over the vibration monitoring parameter setting device.4, the course of work: start the air intake duct power supply, dynamic pressure transducer measures the interior dynamic pressure signal of wind-tunnel air intake duct and obtains effective dynamic measuring data by programmable amplifier, VXI data acquisition system (DAS).The dynamic pressure signal that dynamic pressure in pressure monitoring sensor monitoring air intake duct obtains is through amplifying signal by charge amplifier, and the signal overpressure monitoring parameter after amplifying automatically shuts down the air intake duct power supply by the pressure stop after the parameter of device setting is set.The interior dynamic air current vibration signal of vibration monitoring sensor measurement air intake duct changes and by isolated amplifier, vibration signal is amplified, and turn-offs the air intake duct power supply by vibrating stop after the parameter that the signal after amplification arranges over the vibration monitoring parameter setting device.Dynamic pressure transducer is played a protective role.
Claims (4)
1. protective device of dynamic pressure sensor used in wind tunnel air inlet experiment, comprise pressure monitoring sensor, charge amplifier, pressure monitoring parameter setting device, pressure stop, a N dynamic pressure transducer, a N programmable amplifier, VXI data acquisition system (DAS), Industrial Control Computer, air intake duct power supply, vibration monitoring sensor, isolated amplifier, vibration monitoring parameter setting device and vibration stop, it is characterized in that: 1＜=N＜=300; dynamic pressure variations in flow rate in pressure monitoring sensor monitoring air intake duct, output pressure variations in flow rate signal to charge amplifier amplifies, forced draft rate of change signal overpressure monitoring parameter after amplifying turn-offs the air intake duct power supply by the pressure stop after the parameter that device arranges is set, N dynamic pressure transducer gathers the dynamic pressure data of air intake duct, transfer to the VXI data acquisition system (DAS) after amplifying through N programmable amplifier respectively, VXI data acquisition system (DAS) collection dynamic pressure data are sent into Industrial Control Computer again and are obtained the needed distortion index of air inlet experiment by calculating the distortion index method, in vibration monitoring sensor measurement air intake duct, the dynamic air current vibration changes, output dynamic air current vibration signal to isolated amplifier amplifies, turn-off the air intake duct power supply by the vibration stop after the parameter that the dynamic air current vibration signal after amplification arranges over the vibration monitoring parameter setting device, Industrial Control Computer arranges the parameter of pressure monitoring parameter setting device and vibration monitoring parameter setting device.
2. protective device of dynamic pressure sensor used in wind tunnel air inlet experiment according to claim 1, is characterized in that: described pressure monitoring sensor employing PVDF material pressure transducer.
3. protective device of dynamic pressure sensor used in wind tunnel air inlet experiment according to claim 1, is characterized in that: described vibration monitoring sensor employing PVDF material vibrating sensor.
4. protective device of dynamic pressure sensor used in wind tunnel air inlet experiment according to claim 1; it is characterized in that: described pressure monitoring sensor, dynamic pressure transducer and vibration monitoring installation of sensors are on the same xsect of air intake duct; and evenly distribute by circumferencial direction, connect the earth after above-mentioned three kinds of sensor mask.
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| CN 201110310432 CN102426091B (en) | 2011-10-13 | 2011-10-13 | Protective device of dynamic pressure sensor used in wind tunnel air inlet experiment |
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| CN 201110310432 CN102426091B (en) | 2011-10-13 | 2011-10-13 | Protective device of dynamic pressure sensor used in wind tunnel air inlet experiment |
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| CN102426091B true CN102426091B (en) | 2013-11-06 |
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| CN103234756B (en) * | 2013-04-16 | 2015-09-30 | 中国航空工业集团公司沈阳发动机设计研究所 | A kind of large bypass ratio engine net formula distortion device |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1251899A (en) * | 1998-10-15 | 2000-05-03 | Tlv股份有限公司 | Monitor system with internal power supply |
| CN1722036A (en) * | 2003-12-02 | 2006-01-18 | 中华研升科技股份有限公司 | Control system and monitoring apparatus for reaction plant |
| DE102004039169A1 (en) * | 2004-08-12 | 2006-02-23 | Kaden, Günther | Differential pressure measurement device for use during e.g. natural gas extraction, has pressure sensor for pressure measurement at pressure connections, so that valve unit remains in end position in overload case due to one-sided pressure |
| CN201060083Y (en) * | 2007-07-16 | 2008-05-14 | 阿尔法仪器(天津)有限公司 | Overload protection device of gas pressure sensor |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7010459B2 (en) * | 1999-06-25 | 2006-03-07 | Rosemount Inc. | Process device diagnostics using process variable sensor signal |
-
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1251899A (en) * | 1998-10-15 | 2000-05-03 | Tlv股份有限公司 | Monitor system with internal power supply |
| CN1722036A (en) * | 2003-12-02 | 2006-01-18 | 中华研升科技股份有限公司 | Control system and monitoring apparatus for reaction plant |
| DE102004039169A1 (en) * | 2004-08-12 | 2006-02-23 | Kaden, Günther | Differential pressure measurement device for use during e.g. natural gas extraction, has pressure sensor for pressure measurement at pressure connections, so that valve unit remains in end position in overload case due to one-sided pressure |
| CN201060083Y (en) * | 2007-07-16 | 2008-05-14 | 阿尔法仪器(天津)有限公司 | Overload protection device of gas pressure sensor |
Non-Patent Citations (8)
| Title |
|---|
| 压杆应变式压力传感器在爆炸冲击波载荷测试中的应用;石培杰等;《振动与冲击》;20071231;第26卷(第4期);全文 * |
| 惠增宏等.进气道实验中动态数据采集及处理方法研究.《实验力学》.2002,第17卷(第1期),第48-54页. |
| 无线存储式爆炸冲击波压阻压力传感器研制;韩红彪等;《第五届全国爆炸力学实验技术学术会议论文集》;20100312;全文 * |
| 曾祥炜等.梭式管道爆破保护装置的动态特性.《油气储运》.1999,第18卷(第1期),全文. |
| 梭式管道爆破保护装置的动态特性;曾祥炜等;《油气储运》;19991231;第18卷(第1期);全文 * |
| 石培杰等.压杆应变式压力传感器在爆炸冲击波载荷测试中的应用.《振动与冲击》.2007,第26卷(第4期),全文. |
| 进气道实验中动态数据采集及处理方法研究;惠增宏等;《实验力学》;20020331;第17卷(第1期);第48-54页 * |
| 韩红彪等.无线存储式爆炸冲击波压阻压力传感器研制.《第五届全国爆炸力学实验技术学术会议论文集》.2010,全文. |
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