Failure Mode Analysis Of Aero-Engine Pressure Sensor

As significant parts of aeroengine control systems,pressure sensors play an important role in engine thrust management and condition monitoring.However,aeroengine pressure sensors work in harsh environments with water,vibration,and large temperature range.These environmental factors can cause pressure sensors to fail.The failure of the pressure sensor will have a certain impact on the safety of the aeroengine.The analysis of failure mode,failure reason and failure impact for the aero-engine pressure sensor can provide reference and basis for the airworthiness approval of the aeroengine control system.In this paper,the qualitative and quantitative analysis of the failure mode and its influence of the aero engine pressure sensor is carried out.First,the pressure measurement station,function and general structure of the current aeroengine pressure measurement system are summarized.Then,based on the relevant data,fault tree analysis method was used to analyze the four basic failure modes of the aeroengine pressure sensor: leakage and blockage of pressure acquisition and transmission component,pressure measurement component parameter drift or completely failed.Then,for the above four failure modes,the effects of the four failure modes on the pressure measurement error were calculated and analyzed using qualitative or quantitative methods.For the leakage of pressure acquisition and transmission component,the steady-state leakage model of the pipeline was deduced and solved by MATLAB.The leakage model was verified by numerical simulation.When the leakage occurs,the factors that affect the pressure measurement error are: inlet air pressure and temperature,ambient pressure,leakage hole area,and the length between the leakage port and the inlet;For blockage of pressure acquisition and transmission component,blockage model was deduced on the basis of the leakage model,and solved with MATLAB.When there is an incomplete blockage,pressure response delay occurs,the magnitude of the delay is related to the rate of change of the inlet pressure,the distance between the blockage and the sensor,and the area of the partly blocked hole.For the parameter drift and complete failure of the pressure measurement component,two types of sensors commonly used in aeroengine-piezoresistive pressure sensor and vibrating cylinder pressure sensor – were studied,and characteristic model of the pressure sensor of the two sensors were established respectively.Based on the piezoresistive pressure sensitive element model,the effect of resistance change and temperature compensation failure on the pressure measurement error was analyzed.When a resistance is reduced,the zero point will drift up to 50% of the full range.If the temperature compensation fails,it will show a zero temperature drift and temperature sensitivity drift.The zero temperature drift is related to the initial resistance and temperature coefficient of the resistor.It decreases with increasing temperature.The effect of temperature compensation failure,water and dust on pressure measurement error was analyzed using the vibrating cylinder characteristic model.For the vibrating cylinder,the influence of the temperature compensation failure on its accuracy is less than 1%.The water has a great influence on pressure measurement error.The effect of the accumulated dust on the pressure measurement error depends on the accumulation quantity of dust on a unit area.