Analysis of Flow Control in Compressor Stator by Steady and Pulsed Jets Based on POD Method

Steady and pulsed jets were introduced to the compressor stator upper end-wall. The unsteady cascade flow field under flow was investigated using validated numerical simulations and the Proper Orthogonal Decomposition (POD) method. Detailed analysis was conducted on the vortex structure and the spatial-temporal characteristics of the main modes. The results show that as the jet position moves along the axial direction, the control effectiveness of both steady and pulsed jets gradually weakens. When the jet is injected before the separation point on the suction surface of the cascade, the steady jet can reduce the total pressure loss by up to 9.2% and 7.2%, respectively. In comparison, the pulsed jet can decrease it by 10.2% and 9.2%. The pulsed jet effectively inhibits the development of both the passage vortex and the trailing edge shedding vortex. Additionally, it suppresses the original turbulent pulsation, locks it to the excitation frequency and promotes the transition of the flow field to a more orderly state. The consequences of POD analysis show that the primary structure of the flow field is composed of the first four modes, and the frequencies of their corresponding time coefficients are the fundamental frequency and its harmonics. In the pulsed jet scheme, the time coefficient exhibits a sine-like function distribution, suggesting a stronger coupling between the jet and the flow field. The two jet schemes modified the energy distribution of the primary modes, and this perturbation does not change the number of main modes in the flow field. Compared with the steady jet scheme, the pulsed jet scheme demonstrated higher energy in the flow field and reconstructed the original flow field, further employing its periodic disturbances. Specifically, this reconstruction was mainly embodied in the decrease in the energy proportion of the first-order mode and to enhance in the energy proportion of the remaining main modes.