End-Wall Boundary Layers and Blockages of Multistage Axial Compressors Under Different Conditions

Abstract

End-wall boundary layers and induced blockages are important factors for multistage axial compressors’ performance. This paper investigates hub and shroud end-wall boundary layers, and the corresponding blockages of a five-stage axial compressor under different conditions. The results show that the hub displacement thickness increases from the front to rear stage, whereas the shroud displacement thickness remains almost the same. At the design point, the blockage increases from 2.4% for the front stage to 14.7% for the rear stage, which is dominated by the hub displacement thickness. Under different operating conditions of 100% speed, the blockage is almost the same for the front stage, but increases significantly for the rear stage from 6.0% at near choke to 22.2% at near surge. At peak-efficiency points of different rotational speeds, the blockage remains almost the same. The steady and unsteady results show almost the same trends of displacement thickness and blockage. Compared to unsteady simulations, the time consumption of steady simulations is only one-sixtieth, which can save large amounts of computational resources. Based on the results, the trends of displacement thicknesses and blockages are almost the same in a wide range of operating conditions, which indicates that the flow control in the end-wall region for the design condition would be still effective.