Prediction of Vane Surface Film Cooling Effectiveness Using Compressible Navier-Stokes Procedure and k-ε Turbulence Model With Wall Function

Abstract

A numerical prediction has been performed on the film cooling effectiveness and the total pressure loss of the actual turbine vane geometry. The Navier-Stokes code used in this study is an implicit, cell-centered, finite volume code with k-ε turbulence models. The convection term was stabilized by the variable order up-winding scheme. The film cooling injection has been simulated by adding the prescribed flux terms at the vane surface. The k and ε near wall distribution functions were developed based on the experimental and the DNS results in the literature. The wall functions for k and ε can be used with the selected low Reynolds number version of k-ε turbulence model irrespective of the distance between the wall and the first grid point. This combination would result in lower computational costs, since, near wall grid number can be reduced significantly. Based on the study, the Navier-Stokes predictions were performed on the actual turbine vane geometry. Also, the comparisons were made with the experimental total pressure loss distribution behind the vane row and the mid-span film-cooling effectiveness distribution for single and double row injection cases.

Aerodynamic Loss Increase due to Individual Film Cooling Injections From Gas Turbine Nozzle Surface

“…The outlet Reynolds number during the experiments..was of the same order as that of the designed condition. Therefore, the wall function on the basis of the experimental and the DNS results developed by Fukuyama et al (1995) was coupled with the standard k-e two equation turbulence model. At the upstream boundary, total pressure, total temperature and flow angle were specified, and the upstream-running Riemann invariant was extrapolated from the interior of the solution domain.…”

“…Although each row of SH injections shared the air distributing cavity in the experiments, mass flux through each row was equally provided without considering the local static pressure profile. The turbulence conditions of the slot exit were calculated using the empirical correlation for wall shear stress of Blasius and on the basis of the experiments of Laufer (Fukuyama et al, 1995). It was based on the assumption that the turbulence condition of the flow at the slot exit was represented as the fully developed turbulence in a cylindrical tube corresponding to the hole diameter.…”

“…More details of the code are also described by Fukuyama et al (1995). Preliminary 2-D and 3-D calculations were done for the case without injection.…”

“…Over the past few years, several studies have focused on injection from the nozzle guide vane by using Navier-Stokes procedures. Fukuyama et al (1995) simulated the flow along a linear cascade vane geometry with single and double row film injections from the suction surface using a two-equation turbulence model. They developed k and s near wall distribution functions on the basis of experimental and DNS results in the literature.…”

“…In this paper, 2-D computations with the code developed by Fukuyama et al (1995) have been performed in the six cases of these injections. Three-dimensional computations to simulate injection from discrete holes have additionally been performed for comparison with the results of A 2-D injection.…”