Research On Leak Location Of Spacecraft In Orbit By Acoustic Sensor Array

With the development of the aerospace industry,more space debris is formed in space.Once the spacecraft sealed cabin is broken down by space debris,a gas leak will occur,which seriously threatens the life safety of astronauts and the spacecraft.Therefore,it is very important to realize the detection and location of the gas leak of spacecraft in orbit.It is difficult to realize gas leak detection in a vacuum environment due to the vacuum condition,bulkhead structure complexity,and leakage randomicity.In this thesis,the acoustic characteristic of the gas leak signal is studied for various bulkhead structures based on acoustic array sensing technology.The leak location algorithms are developed and the related application devices are designed.The main innovations include:The model of the gas leak flow and the acoustic sourse is established to simulate the leak process in vacuum environment.The leaking gas will expand rapidly into the vacuum environment,forming a turbulent jet whose diameter is several times of the leakage hole.The propagation characteristic of the leak signal is studied in both spacecraft flat plate and stiffened plate.The difficulties caused by dispersion and attenuation reflection caused by stiffeners on leak location are discussed.The beam-forming leak location method based on frequency matrix weighting is proposed.By using beam-forming energy focusing,the location is realized.The problem of randomicity of the leakage hole’s size is solved by selecting the signal frequency band and compensating the wave velocity spectrum matrix.The adaptive accurate location of the leak in the vacuum environment of spacecraft flat plate structure is realized.The wavenumber domain imaging algorithm based on Bayesian estimation is proposed,which uses wavenumber domain imaging to realize leak location,uses wavenumber domain filtering to remove pseudo-points,and effectively reduces the effect of stiffeners on leak location.Bayesian estimation is used to further reduce the location error and realize the accurate leak location of spacecraft stiffened structure.According to the strategy of spacecraft leak acoustic detection,three application devices of spacecraft leak acoustic detection are developed,including distributed acoustic sensor impact&leak detection system,acoustic emission array leak detection system,and portable ultrasonic leak detector.