Effects of rim seal cavity geometric features on turbine performance

Cooling flow is injected into the mainstream through the inter-stage gap in turbines to avoid hot gas ingestion. However, losses due to the mixing process between main flow and cooling flow directly lead to the penalty of turbine performance. In order to investigate the effects of rim seal cavity axial position and axial clearance on turbine performance and end wall flows, 3-D steady numerical simulation of was conducted. The results indicate that shear induce vortex is formed due to the shear interaction between main flow and cooling flow and develops into hub passage vortex which dominates the hub end wall region. Variation of rim seal cavity axial position and axial clearance result in the opposite trend of isentropic efficiency and sealing efficiency. Thus, turbine aerodynamic performance and cooling requirements should be made a compromise in the design process.