Largest Lyapunov Exponents of Engine Experimental Data
Wu Youli(1,2),Dong Fuan(2),Lv Jianwei(1),Li Shifei(1)
(1 Engineering College, Air Force Engineering University, Xi’an, 710038, China)
(2 Applied Mathematic Faculty, College of Arts and Science, Air Force Engineerin g University, Xi’an 710051, China)

Abstract: The largest Lyapunov exponents of the pressure signal of a certaineng ine with eight axial compressor stages are investigated: The stall and surge inception points possessing the same dynamic characteristics are all located on the boundary of a limit circle. A new method for detecting the first stage of stal l is presented, where the largest Lyapunov exponent zero point is regarded as the initial stall of the compressor, and the stage within which the largest Lyapu nov exponents firstly reaches to zero is indicated as the first stall one. The computational results demonstrate that the method enables to detect stall incepti on signal of compressor 0.2s before the beginnig of deep rotating stall, and the third stage is noted as first stall stage.
Keywords: Lyapuonv exponent, compressor, stage of the first stall, stall, surge.