Conjugate Heat Transfer Modeling of a Film-Cooled, Flat-Plate Test Specimen in a Gas Turbine Aerothermal Test Facility

The aerothermal test facility at the National Energy Technology Laboratory (NETL) provides experimental data at realistic gas turbine conditions to enable the development of advanced film cooling strategies for future gas turbine components. To complement ongoing experimental studies, Fluent computational fluid dynamics (CFD) models have been developed to provide a framework for comparison of cooling strategies and to provide fundamental understanding of the fluid dynamic and conjugate heat transfer (CHT) processes occurring in the experiments.The results of a parametric study of the effects of mesh density, near-wall refinement, wall treatment, turbulence model and gradient discretization order on the CHT predictions are presented, and the simulation results are compared to experimental data. A flat plate test specimen with a single row of laidback fan-shaped film cooling holes was modeled at a process pressure of 3 bar, a process gas flow rate (m) of 0.325 kg/s (Re ≈ 100,000) and a blowing ratio (M) of 2.75. Three polyhedral mesh cases and three turbulence models (Realizable k-e, SST k-ω and RSM Stress-ω) were implemented with enhanced wall treatment (EWT) and 1st-order and 2nd-order gradient discretization.The results show that the choice of turbulence model will have little effect on the results when utilizing the finest mesh case and 2nd-order discretization. It was also shown that the SST k-ω turbulence model cases showed minimal mesh sensitivity with 2nd-order discretization, while the Re k-e turbulence model cases were more sensitive to mesh density and near-wall refinement. The results thus indicate that the SST k-ω turbulence model can predict the convective heat transfer adequately with a relatively coarse mesh, which will save computational resources for later inclusion of radiative heat transfer effects to provide comprehensive CHT predictions.Copyright © 2013 by ASME