Development Of High Temperature Resistance Optical Fiber Tip-Timing Sensor

The blade vibration online monitoring system based on the blade tip timing principle has become the most effective methods of blade vibration monitoring and evaluation in the aero engine component and machine experiments.The blade tip timing sensor is used as the sensing element of the blade vibration online monitoring system.It is installed on the engine casing,and the end is directly in contact with the internal airflow of the engine.The operating temperature range of the blade tip timing sensor is from 200? in the fan stage to 1300? in the turbine stage.At present,the commonly used blade tip timing sensors are mainly divided into optical fiber type,capacitive type and eddy current type.Among them,the optical fiber type tip timing sensor is small in size,wide in bandwidth and high in measurement accuracy,and has outstanding engineering application value.However,the maximum temperature resistance of the fiber optic tip timing sensor developed in China is only 700?,which cannot meet the requirements of turbine blade vibration monitoring.Therefore,it is urgent to develop a fiber optic tip timing sensor that can withstand 1300? high temperature.This article addresses the online monitoring requirements for blade vibration at 1300?.A design scheme of high temperature resistant optical fiber tip timing sensor using active cooling method is proposed.Focusing on key technologies such as active cooling sensor modeling,model simulation and optimization,sensor thermal radiation interference suppression.In-depth research work was carried out,and a 1300? resistant sensor and thermal radiation interference suppression module were developed.The main work of the thesis is as follows:1.A design scheme of high temperature resistant optical fiber tip timing sensor based on active gas cooling is proposed.A hollow sensor structure is constructed by using a large diameter metal shell wrapped with a small diameter fiber.The optical fiber is isolated from the high temperature environment by cooling gas and cooling gas film.Using ANSYS to build a sensor simulation model,using a thermal fluid-solid coupling simulation analysis method,focusing on comparing the influence of cooling gas outlet shape,cooling gas temperature,sensor installation depth and other factors on the temperature resistance of the sensor,and clarifying the best model of the sensor.Under the simulation conditions,the optimal design of the optical fiber tip timing sensor resistant to 1300? high temperature is realized.2.The radiation interference law of turbine rotor,high temperature gas and high temperature soot in high temperature environment is analyzed.Using the blackbody radiation law,calculate and compare the intensity of radiated interference in different bands,and select the band with weaker overall radiated interference.Based on the sensor structural parameters of the simulation model,a high temperature resistant fiber tip timing sensor was developed.Combined with optical filtering technology,the module of radiation interference suppression and blade tip timing signal conditioning is designed,while realizing the development of the high-temperature-resistant sensor,it effectively suppressed the influence of radiation interference on the blade tip timing signal under high-temperature environment.3.A high-temperature test platform was built and a temperature-resistant verification experiment of a high-temperature resistant optical fiber tip timing sensor was carried out.The sensor was tested by simulating a high-temperature environment.The agreement between the experimental result and the simulation result is better than 3.97%.The signal conditioning module with radiation suppression effect has effectively suppressed radiation interference in the field test,and the signal-to-noise ratio of the blade tip timing signal is better than 26.02 dB.