Endwall Contouring for Improving Aerodynamic Performance in a High-Pressure Turbine Cascade

The endwall contouring has proven to be an effective technique in controlling the impacts of secondary flow within turbomachinery. A baseline cascade with the original axisymmetric endwall (BASE) has been redesigned with a non-axisymmetric contoured shroud endwall (EW-B1), and both configurations are investigated through experimental and numerical methods. The endwall is profiled through the B-spline surface method with the purpose of reducing the overall total pressure loss at the exit. The experimental studies involve flow field traverses at the exits of both cascades. Numerical calculations are conducted to gain a deeper understanding of the effects of endwall contouring. The numerical results exhibit good agreement with the experimental results, both in loss and flow angle. The results demonstrate a significant reduction in losses and secondary kinetic energy in EW-B1. The causes of the high-loss region and the overturning near the shroud are analyzed using computational fluid dynamics (CFD), as well as the changes in pressure fields and vortex structures within the cascade passage. The weakening of the horseshoe vortex and the radial movement of the passage vortex are confirmed to be the primary reasons for losses reduction.