Research On Design And Simulation Of Fluctuation Pressure Sensor On The Surface Of High Speed Train

When the speed of the high speed train is more than 300Km/h,the aerodynamic noise will become the main component of the train noise,and the fluctuating pressure is the root cause of the aerodynamic noise.The fluctuating pressure of high speed train has many characteristics,such as low amplitude,wide frequency band,easy to be disturbed,and so on,so there has a higher demand on test performance of sensor.Micro-piezoresistive sensor has many advantages,such as high frequency response,high sensitivity and good structural performance,it is often used in the aerodynamic test of high speed train surface.However,there are still some shortcomings of micro-piezoresistive sensor in the measurement of the fluctuating pressure.To solve the above problems,this paper carries out the numerical simulation of the testing principle of the micro-piezoresistive sensor,and studies the method to improve the performance of the structure,and analyzes the vibration and temperature interference of the sensor,which provides a theoretical basis for the improvement of the performance of the sensor and the error interference separation of the test signal.In this paper,the micro-piezoresistive pressure sensor is used as the analysis object,using Solidworks software to establish the core sensitive component model,and carrying out the numerical simulation by Ansys,extracting the results and calculating the voltage output.And this paper presents a combined numerical simulation method of structural and electrical for model dividing resistance.Based on the analysis of the flat membrane structure of the sensor,this paper proposes the double island structure and the double island-cross beam structure of the sensor,and also carries out the optimal design of the key feature parts of each structure.Then the interference output of the three structures of the flat membrane,double island and double island-cross beam under vibration are compared and analyzed by numerical simulation.The total output of pressure interference by the vibration of the box is measured by the box test.And the effect of flow field by the vibration of the box is obtained by CFD numerical simulation.Through the numerical simulation of the structure and the performance index of the sensor,the interference of vibration to the sensor is obtained and compared.The temperature and pressure measurement points are selected to simulate the temperature effect of the sensor,and the thermal zero drift and sensitivity drift are analyzed.And the temperature performance of domestic and imported sensors is tested by temperature test.The coupling interference analysis among of temperature,vibration and pressure is carried out,analyzing the method of establishing the multi factor interference model of multi input and single output.designing the structure of the sensor array and proposing the method of measuring the fluctuating pressure by using the array measuring plate instead of the wall of the wind tunnel model car.The results showing that,by optimizing the structural performance of the sensor,we can get a double island-cross beam structure sensor with a range of 20KPa,a sensitivity of 32.25mv/KPa and a linearity of 0.293%,which can meet the requirements of the test of fluctuating pressure.The size of the membrane is 3 × 3 × 0.02mm and the size of the bottom surface of the island and cross beam both are 1.4 × 1.4mm.Based on the analysis of the vibration interference,the acceleration sensitivity of the flat membrane structure is 0.6Pa/g,and the acceleration sensitivity of the double island structure and the double island-cross beam structure is 4.4-4.9Pa/g,and the influence of the vibration on the pressure change is consistent with the vibration trend.The total effect of the vibration on the air pressure extracted by box test is approximately equal to the sum of the CFD simulation on the flow field and the vibration disturbance of the sensor.Based on the numerical simulation of the temperature effect of the double island-cross beam structure,the variation of the sensitivity with temperature is S =-1.194×10-6t3 + 2.206×10-4t2-0.01453t+ 32.5,and the variation of zero drift with temperature is a=0.1474×t-1.908.The zero drift trend of MSP1015-100 sensor is similar to that of numerical simulation,and the zero drift trend of 8515C-15 sensor is opposite to that of numerical simulation.The multi factor model of multi input and single output can be established effectively based on the combination of theory,numerical simulation and test.And the designed array structure is of good performance and consistency,which can effectively measure the fluctuating pressure.