Optimization of Turbine Non-Axisymmetric Endwall Profiling and Flow Field Control Mechanism Considering the Coupling of Rim Seal Flow

Aiming at the aerodynamic loss induced by the mixing between the secondary flow in the turbine rotor passage and the rim seal flow in aero-engines, a three-dimensional non-axisymmetric endwall aerodynamic optimization platform was constructed for a turbine stage, and the optimal design of turbine non-axisymmetric endwall considering seal flow coupling was carried out. Firstly, the non-axisymmetric endwall profiling optimization of the turbine stator was completed under stage environment, and the regulation law of non-axisymmetric endwall on stator and rotor passage vortices as well as turbine aerodynamic performance before and after optimization was analyzed. Under the condition of seal flow coupling, the influence of its mixing with the mainstream on the turbine endwall flow field was investigated, and the non-axisymmetric endwall profiling optimization of the turbine rotor was accomplished. Results show that the stator non-axisymmetric endwall optimization increases the peak isentropic efficiency of the turbine by 1.47% relative to the baseline. This optimization significantly improves the local flow characteristics near the stator endwall, weakens the intensity of the rotor passage vortex, and reduces the endwall flow loss. Based on the consideration of seal flow coupling, the strong mixing effect between seal flow and mainstream leads to a reduction in turbine aerodynamic efficiency, while the rotor non-axisymmetric endwall optimization further enhances the turbine peak isentropic efficiency by 1.19%, reduces the passage vortex intensity in the endwall region, and mitigates the secondary flow loss.