Experimental and numerical investigation of passive flow control using L-shaped endwall groove in an axial flow compressor stage

To investigate the control effect and flow mechanism of the L-shaped endwall groove on corner separation in the real compressor stage, a single stage axial flow compressor is selected as the research object and the L-shaped grooves are introduced on the stator casing side. First, the experimental measurement is conducted on the optimal L-shaped groove obtained through a full factorial experimental design, and the results demonstrate that the optimal groove has a great control over the endwall flow. Moreover, the peak efficiency is improved by 0.9% and the stall margin is increased by 4.46%. Then, the flow field visualization of numerical results and analysis of variance method are employed to analyze the control mechanism and parameter control law of the L-shaped groove. It is found that the L-shaped groove can guide the skewed inlet endwall boundary layer towards the streamwise direction due to its confinement effect, thereby delaying the onset of corner separation and reducing the size of ring vortex. As a result, the aerodynamic performance of the compressor is enhanced. Furthermore, the groove depth and groove width play a significant role in controlling endwall flow among the three L-shaped groove design parameters. The larger groove depth and smaller groove width enhance the capability of the streamwise groove to constrain the endwall boundary layer, leading to a greater reduction in endwall loss.