Elimination of the Horse Shoe Vortex in Axial Turbine Vane Cascades via Airfoil Shape Optimization

摘要

The horseshoe vortex, an aerodynamic phenomenon in axial turbine vane cascades, results in a significant deterioration in the aerodynamic performance of the airfoil. This paper presents the results of the aerodynamic redesign of an axial turbine stator vane for the purpose of horseshoe vortex diminishment. Initially, a loaded turbine stage was designed for typical aero-engine turbine conditions, named "first generation" in this paper. The flow at the stator inlet is analyzed (as part of a stage domain) and modeled by means of a Navier-Stokes computation using the upstream rotor exit conditions and employing the SST turbulence model. The resulting computed boundary conditions along the stator span establish new velocity triangles at the hub and tip regions, as the flow at the end walls is carefully studied. The stator design is optimized through a redesign of the hub and tip airfoil sections using the resulting boundary conditions. The airfoil is then restacked in three dimensions and the flow around the vane is again analyzed using the same boundary conditions as the first generation stator. The presented results show that the horseshoe vortex is significantly diminished after stator design-based optimization. Furthermore, the rotor-stator interaction is also analyzed and the conditions upstream of the optimized vane are also considerably improved.