Research On Fault Diagnosis Of Aircraft Bleed Air Leakage Based On Eutectic Salt Sensor

Bleed air leakage is a common fault type of civil aircraft.It is an effective way to detect the bleed air leakage of aircraft with the eutectic salt type overheat detector.The research on the air leakage fault diagnosis of aircraft is of great significance to improve the operational efficiency of civil aviation flight and the operational reliability of civil aviation aircraft.In this subject,the theoretical analysis,experimental and simulation methods are used to study on the fault diagnosis of aircraft bleed air leakage based on the eutectic salt type overheat detector.The main work and results are as follows.1.The electro-chemical properties of eutectic salt are investigated.The theoretical principle of the eutectic salt overheat detector applied in the bleed air leakage fault diagnosis of aircraft is deeply analyzed.2.The design,layout and operation commission of the typical closed loop detection system for aircraft bleed air pipeline are described in detail.3.The electrical characteristics of the eutectic salt type detectors at different frequencies,voltages and temperatures are investigated by means of E4980 A precision LCR and other devices.The experimental data are analyzed and summarized,and the electrical parameters of the eutectic salt detector are obtained,as well the equivalent model of the standard parameters and the equivalent model of the overheat detection are established.4.The location of bleed air leakage fault is deeply studied.The principle and circuit design of the current ratio method applied to the bleed air leakage fault location of aircraft are analyzed in detail.The fault location of air leakage under different frequency and distributed capacitance is simulated by using Multisim and other software.The idea of bleed air leakage location by using dichotomy method,bridge method and time domain reflection method is proposed.In the end,the author puts forward some suggestions for the research on the fault diagnosis of bleed air leakage based on the eutectic salt detector.