Numerical Simulation of Turbulent Flows for Turbine Blade Heat Transfer Applications

Abstract: Turbine blade heat transfer is an important engineering problem characterized by complex flow fields and high turbulence levels. This thesis is focused on using a full Navier-Stokes solver with two-equation eddy-viscosity models to predict external heat-transfer in single-stage, linear, two-dimensional uncooled turbine cascades. The main application is supersonic space turbines, but most results presented are for subsonic and transonic cascades, for which there are measurements to compare with.

The turbulence models evaluated include the algebraic Baldwin-Lomax model, three low Reynolds k-.epsilon. models (Chien, Launder-Sharma and Nagano-Tagawa) and two k-.omega. models (Wilcox standard and transition). A new non-linear k-.omega. model has also been developed, which improves the predictions in the leading edge region significantly. Results are generally in good agreement with measurements. The main problem, which remains unsolved, is transition prediction.

The numerical method is a block-structured explicit Runge-Kutta finite-volume scheme. A detailed description of this method and the governing equations is given in the thesis. The numerical quality of the simulations has been thoroughly investigated in order to ensure that the results are representative of the turbulence models and not the numerics. Grid and scheme independence has been verified, and a few general guidelines about the numerics are summarized.