The Design And Implementation Of Aero-engine Exhaust Gas Monitoring System Based On ECT

Aero-engine, as an important component of the aircraft, it has a complex and special structure, a harsh working environment and a frequent switching working condition. These factors are easy to bring the engine into wear and tear and lead to serious failure, aviation accidents, endangering flight safety and the safety of human life. Therefore, the monitoring of the aircraft tail gas is of great significance. In order to obtaining the real-time image, motoring the tail pipe and particle information of gas-solid two-phase flow in the flow in aero-engine, and provide reference for engine maintenance. Electrical Capacitance Tomography is used to monitor exhaust nozzle of gas path. ECT is currently one of the most mature technology in Electrical Tomography. The technology has the advantages of no radiation, no invasion, high reliability, real-time and low cost advantages, but it is seldom used in dilute phase flow because of low spatial resolution measurement.In order to study on the characteristics of the aero-engine exhaust gas in-depth, to make fault diagnosis of aero-engine, a hardware acquisition system was developed based on ETC. By using ECT on the measurement and research of aero-engine exhaust, the main work and the results obtained are as follows:1. By analyzing, researching and absorbing the results and analysis of ECT sensor, according to the aero-engine model and the actual injection tail pipe sensor structure. A circular ECT sensor with 16 electrodes is built according to the aero-engine model and the actual injection tail pipe sensor structure.2. By analyzing the physical characteristics of sensitivity field in ECT sensor, a mathematical description was put forward. Then, the two-dimensional finite element method was used to solve the negative problem and analyze the positive problem in ECT.3. A circular ECT sensor hardware acquisition system with 16 electrodes is built. The system is improved based on the absorption of previous research. The Xilinx FPGA is worked as the core processing control unit, by the digital demodulation method, the real-time performance of the system is improved; when the input signal frequency and amplitude is constant, the smaller range and faster conversion speed ADC is used; As PCB layout, signal integrity, power integrity and EMC are integrated into the design philosophy, the design of system hardware become more reasonable, optimization degree is higher.4. With the two classic ECT imaging algorithms--linear back projection algorithm(Linear Back Projection, LBP) and Landweber iterative algorithm, and combined with the designed ECT sensor hardware acquisition system, real time imaging is achieved to verify the performance of the hardware system and software system. The results show that the performance is stable, the reconstruction of the image is clear and the system is strong in extension.