Aerodynamic optimization of a heavy-duty gas turbine vane: Synergizing non-axisymmetric endwall contouring with 3D blade profiling

To address the complex flow characteristics within the first-stage vane passage of a high-load heavy-duty gas turbine under transonic conditions (with an exit Mach number of 0.9), this study conducts an integrated optimization design and aerodynamic performance evaluation of non-axisymmetric endwall contouring and three-dimensional (3D) blade profiling. The methodology employs B-spline parameterization for the endwall, a modified 11-parameter method for the airfoil, and a bowed blade design based on leading-edge stacking. Validation is performed using five-hole probe measurements in a transonic sector cascade wind tunnel and numerical simulations utilizing the SST γ-θ transition model. Experimental and computational results indicate that the optimized non-axisymmetric endwall effectively reduces the transverse pressure gradient in the endwall region and establishes a pressure barrier. This suppresses the migration of the endwall boundary layer and the development of vortex structures while maintaining minimal impact on the mainstream flow. Concurrently, the 3D bowed blade design enhances control over secondary flows and flow losses by redistributing the blade surface pressure and the radial pressure field within the cascade passage. Comparative data analysis reveals that the integrated optimization synergizes the advantages of both approaches, significantly improving aerodynamic performance. Numerical simulations indicate a 11.955% reduction in the total pressure loss coefficient at the cascade outlet, while wind tunnel measurements demonstrate an even more substantial reduction of approximately 30.915%.