Three Dimensional RANS Prediction of Gas Side Heat Transfer Coefficients on Turbine Blade and Endwall

Abstract

This paper presents a study using 3D computational fluid dynamics (CFD) based on Reynoldsaveraged NavierStokes (RANS) equations to predict turbine gasside heat transfer coefficients (HTC) on the entire airfoil and endwall. The CFD results at different spanwise sections and endwall have been compared with the flatplate turbulent boundary layer correlation and with the data in a NASA turbine rotor passage with strong secondary flows, under three different flow conditions. The enhancement effects of secondary flow vortices on the blade surface and endwall heat transfer rate have been examined in detail. Analyses were conducted for the impact of Reynolds number and exit Mach number on heat transfer. The SST, kة›, V2F, and realizable kة› turbulence models have been assessed. The classical loglaw wallfunctions have been found to be comparable to the wallintegration methods but with much reduced sensitivity to inlet turbulence conditions. The migration of hot gas was simulated with a radial profile of inlet temperature. CFD results for midspan HTCs of two other airfoils were also compared with test data. Overall, results are encouraging and indicate improved HTC and temperature predictions from 3D CFD could help optimize the design of turbine cooling schemes.