Assessment of a film-cooling flow structure by large-eddy simulation

Abstract

Large-eddy simulation results using the approximate-deconvolution subgrid-scale model (ADM) are reported for a jet-in-crossflow configuration related to the film-cooling of turbine blades. Here, relatively cool air is ejected from a large isobaric plenum through an oblique round nozzle into a hotter turbulent boundary layer. The parameters are chosen in accordance with typical film-cooling conditions of turbines. For computational economy, a steady mean-turbulent inflow profile is used for the crossflow. The adequacy of this simplification is evaluated. The properties of the mean flow field are investigated and the mean film-cooling efficiency is compared to results from the literature. Special attention is paid to the flow structure inside the jet nozzle, which is considered to have a key influence on the mixing process. The physical understanding of film cooling is deepened with an illustration of the instantaneous flow field and its connection to the findings for the mean flow.

Keywords:

• film cooling
• jet in crossflow
• large-eddy simulation
• approximate-deconvolution model

Acknowledgements

Part of this work was carried out with support of the project “HPC-Europa” of the European Community. The hospitality of Professor U. Rist and his group at the Institute of Aerodynamics and Gasdynamics (University of Stuttgart), as well as the support of the High Performance Supercomputing Center Stuttgart (HLRS), are greatly appreciated. The authors thank Professor R. Abhari and his group at the Turbomachinery Laboratory (ETH Zurich) as well as F. Keiderling for fruitful discussions.