A Muti-direction Pressure Measurement Method Of Aero Engine Internal Flow Based On A Fiber Optic Integrated Probe

The multi-direction dynamic pressure of the internal flow is an important performance parameter in the development of aero-engine,which directly determines the stability of the actual operation of the engine.The existing electrical pressure sensors have comparably poor temperature resistance,large volume and inaccurate pressure measurement in the aero-engine pressure measurement.Compared with the existing electrical sensing methods,the optical fiber Fabry-Perot sensor has the advantages of high sensitivity,no electromagnetic interference and high temperature resistance,etc.It is expected to solve the above problems by introducing it to the multi-direction dynamic pressure detection of the engine internal flow field.Therefore,an integrated probe based on fiber Fabry-Perot sensor array is proposed in this thesis for multi-direction dynamic pressure measurement of aero-engine internal flow.Theoretical analysis and experimental research were carried out from the aspects of integrated probe structure design,multidirection airflow conduction and pressure sensing mechanism,integrated probe technology.Research works have been carried out as below:(1)Multi-direction dynamic pressure measurement scheme and principle analysis of integrated probe.Based on the analysis of the requirements of multi-direction high-speed dynamic pressure measurement for aero-engine internal flow,an integrated probe based on optical fiber Fabry-Perot sensor array is proposed.The principle of multidirectional airflow conduction with integrated probe and the principle of pressure sensing with fiber Fabry-Perot sensor array are analyzed.(2)Structural optimization design of integrated probe pressure conduction unit.According to the basic principle of multi-direction air conduction of integrated probe,the conduction unit model was established by FLUENT,and the influences of parameters,such as angle of cone,pressure hole diameters,depth,etc.on the air conduction characteristics were analyzed.The results show that the diameter of pressure hole should be as large as possible within the allowable range.In a small range,the depth of pressure hole does not affect the performance of the integrated probe.Considering the Angle range of high-speed incoming gas and the accuracy of pressure measurement,the optimal cone angle of the probe is 20°.(3)Structural optimization design of integrated probe pressure sensing unit.According to the pressure sensing principle of optical fiber Fabry-Perot sensor,the material selection and size design of the pressure sensing diaphragm are carried out to ensure that the frequency response of the diaphragm meets the requirements of 10 k Hz ～30k Hz.Moreover,the influence of factors such as the inclination angle of optical fiber,lateral offset and the inclination of the diaphragm on the sensing signal and pressure measurement error is analyzed.The results show that when the external pressure is1.5MPa,the optical fiber offset is less than 29μm,the optical fiber tilt angle is less than5.72° or the diaphragm tilt angle is less than 5.50°,the pressure measurement accuracy of Fabry-Perot pressure sensor is less than 0.1%.Based on the above analysis,the supporting structure of the integrated probe was optimized by replacing the curable adhesive with optical fiber core plug.(4)Experimental study on performance verification of integrated probe.The research on the design and manufacture of the single-hole pressure sensor and the 5-hole integrated probe is carried out.The static pressure performance of the single hole pressure sensor and the integrated probe was verified by building a pressure test system.The results show that: the repeatability error of the single-hole pressure sensor is less than 2.37% and the maximum error is less than 0.26% under the pressure of 0.7MPa～1.6MPa.The repeatability error of the integrated probe sensor is less than 2.98%,and the maximum error except hole 5 is less than 0.42%.