Flow structure and surface heat transfer from a turbine component endwall contoured using the ice formation method

Abstract

Steady-state flow structure and surface heat transfer characteristics are numerically predicted for a turbine vane passage, which is contoured using the ice formation method, using ANSYS® Fluent version 12.1. Utilized are an SST turbulence closure model with a low-Reynolds formulation, along with a pressure-based approach to solve the governing equations with the SIMPLE algorithm. The solution domain is spatially discretized with a hybrid grid, created with the commercial grid generator CENTAUR™. The endwall contour shape is obtained using an IFM or ice formation method, which relies upon natural processes wherein energy dissipation and entropy production are minimized. This ice-contouring is imposed only within the vane passage, with endwall transition regions just upstream and just downstream. Particular attention is devoted to the intricate and detailed flow structural variations which are present near the endwall, both through the vane passage and downstream of the vanes. Considered are surface oil flow visualization distributions, vortex distributions, flow pathline distributions, and variations of the z-component of velocity, including their effects of ice-contoured flow structure on surface heat transfer coefficients, relative to a flat, baseline endwall for a turbine flow passage with air flow for a vane chord Reynolds number of 49,900. Results show that contouring significantly alters the endwall heat transfer coefficient distribution, with local values which are both lower and higher compared to baseline results. Such changes are strongly linked to the altered flow field due to the contouring, including changes to passage vortex advection and development.