Experimental Study On A Plasma Wind Speed Sensor For Measuring The Wake Flow In A Compressor

The aerodynamic efficiency of an aero-engine compressor is closely related to the blade structure design.In order to reduce the flow loss caused by separated flow transition and wake mixing,it is necessary to measure the wake flow field of the blade to obtain the flow distribution around the blade.In this paper,the characteristics of glow discharge excited by different power sources and the influence of the main parameters of glow discharge on the technical performance of plasma wind speed measurement are studied.Based on this,a plasma wind speed sensitive element which can be used to the measure compressor wake flow is designed and tested.The main conclusions are as follows:(1)Comparison of the discharge characteristics and the sensitive law of the convection field excited by two types of power supply.The results show that the stability and sensitivity of AC glow discharge are better than that of DC glow discharge.In addition,the controllability of carrier frequency makes the frequency response of AC glow discharge reach hundreds of kHz,so it is more suitable for the measurement of high frequency disturbance flow field of blade wake.(2)The influence of the main parameters of glow discharge on the measurement of plasma wind speed is studied.The results show that the tungsten wire with a diameter of 300μm is used as the electrode and the gap between the electrodes is maintained between 60μm and 100μm,the glow discharge has better stability under the action of the flow field.It is found that the increase of discharge current can increase the range of the sensor,but increase the sputtering loss of the electrode.In addition,increasing the output frequency of the power supply can improve the discharge efficiency and frequency response,but it also accelerates the sputtering loss of the electrode.(3)Based on the above research,the plasma wind speed sensor is designed and the performance is tested.Experiments show that the designed element can be used in the environment of less than 500℃,and it has the characteristics of low temperature drift.It is verified that the series connection of capacitance and resistance in the circuit can improve the discharge stability and reduce the output noise significantly.A time-dependent correction function was proposed to solve the problem of output inconsistency caused by electrode loss.In the dynamic test,the sensor captures the turbulence signal of more than 50 kHz and the harmonic signal of more than 100 kHz.The response time obtained in the shock test was less than 1ms.