Nonlinear analysis of the process of loosing compressor aerodynamic stability in a turbojet engine

The process of loosing compressor aerodynamic stability in a turbojet engine was analyzed using the correlation integral method. Phase space was reconstructed based on compressor static pressure signal during throttling of the engine. Distinct change among attractor structure of the reconstructed phase space was observed and corresponding correlation integral values were calculated to quantify the change of the compressor internal flow. It showed that the tip region of 1st stage lose its stability first, and then 2nd stage, followed by 3rd and 4th stages during throttling. 1st and 2nd stages manifested progressive stall while 3rd and 4th stages manifested abrupt stall. Instability symptom was first detected in the root region of 3rd stage, which developed rapidly and led to full-span stall. Low-pass filtering can improve the effectiveness of correlation integral method in stall precursor detection. Thus, nonlinear correlation integral method is an effective means in the investigation of the process of loosing compressor aerodynamic stability.