Prediction of Film Cooling on Gas Turbine Airfoils

Abstract

A three-dimensional Navier-Stokes analysis tool has been developed In order to study the effect of film cooling on the flow and heat transfer characteristics of actual turbine airfoils. An existing code (Amone et al., 1991) has been modified for the purpose. The code is an explicit, multigrid, ceil-centered, finite volume code with an algebraic turbulence model. Eigenvalue scaled artificial dissipation and variable-coefficient implicit residual smoothing are used with a full-multigrid technique. Moreover, Mayle’s transition criterion (Mayle, 1991) is used. The effects of film cooling have been incorporated into the code in the form of appropriate boundary conditions at the hole locations on the airfoil surface. Each hole exit is represented by several control volumes, thus providing an ability to study the effect of hole shape on the film-cooling characteristics. Comparison with mid-span experimental data for four and nine rows of cooling holes is fair. The computations, however, show a strong spanwise variation of the heat transfer coefficient on the airfoil surface, specially when the shower-head cooling holes are on.