11th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
The interaction between the main and the secondary flow caused by leakage through labyrinth seals lowers the overall performance of an axial compressor. In this study, three cavity outlet variants have been implemented in the third stage of a four-stage high-speed axial compressor in order to investigate the influence of the injection of leakage mass flow into the main flow path. Three-dimensional steady RANS simulations using the SST turbulence model and the multi-mode transition model are performed for all configurations. For the main flow path of the shroudless configuration, the turbulence model predicts the total pressure profiles at the design operating point with sufficient accuracy. Due to the cavity discharge angle of the most efficient configuration, the leakage mass flow slows the main flow near the hub. When this main flow is restrained, the axial component of the main flow near the hub is reduced. This reduction increases the flow angle, leading to a better flow distribution near the hub zone at stator inlet. In addition, the reduction of the axial velocity allows better thermal mixing between the main flow and the leakage flow, increasing the main flow temperature near the hub.