Effects of End Wall Boundary Layer Suction on Performance and Flow Field in a Counter-rotating Compressor

Based on the flow field of a counter-rotating compressor, numerical investigation was conducted on the end wall boundary layer suction of the rear rotor in the stage environment. Research results show that with the increase of suction flow rate, the compressor efficiency increases firstly and then decreases, and the efficiency of compressor improves by 0.85% for the best suction scheme. Suction makes R1 inlet flow deviate towards the axial direction and its tip leakage flow be slightly weaker accordingly with better tip region flow field. For R2, suction weakens the intensity of R2 tip leakage flow significantly and increases the flow capacity in the tip region; on the other hand, suction enlarges the flow separation range at the suction surface trailing edge of R2, resulting in larger flow loss. Ultimately, the suction effect is the game result between the loss increase caused by R2 suction surface trailing edge separation at the high blade span and R2 tip leakage flow loss reduction gain, which is also the internal flow mechanism of the compressor efficiency change rule with suction flow rate. Further, the reason why suction enlarges the flow separation range at R2 suction surface trailing edge is that a certain mass flow rate of the main flow is removed via suction slot and this makes the flow rate increasing amplitude of blade passage behind the suction slot be lower than increasing amplitude of tip effective flow area, resulting in greater airflow diffusion degree.