A Comparison of Hybrid Reynolds-averaged Navier-Stokes/Large-Eddy Simulation (RANS/LES) and Unsteady RANS Predictions of Separated Flow for a Variable-Speed Power- Turbine Blade Operating with Low Inlet Turbulence Levels

Report No. ARL-TR-8191
Authors: David T Booth
Date/Pages: October 2017; 39 pages
Abstract: A comparison of hybrid Reynolds-averaged Navier-Stokes/Large-Eddy Simulation (RANS/LES) and unsteady RANS computations for unsteady separated flow prediction of a linear turbine blade cascade operating with large incidence angle variation is described. The computations comprise a periodic single blade that represents the midspan section of a variable-speed power-turbine blade that was tested in NASA Glenn Research CenterĂ¢??s Transonic Turbine Blade Cascade Facility. A commercial, off-the-shelf software package, Pointwise and CFD++, was used for the grid generation and computations. Simulations were assessed at low inlet turbulence levels for positive and negative incidence angles that represent turbine cruise and takeoff conditions. Comparisons of results for blade loading and loss were made to test data from the transonic tunnel. Comparisons of results for separation predictions were made between the hybrid RANS/LES and RANS computations. Comparisons of separation prediction revealed significant differences in location and extent of separation between the models and grid types.
Distribution: Approved for public release
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Last Update / Reviewed: October 1, 2017