Sensitivity study of the SA-DDES shielding function

Paper i proceeding, 2018

In this paper the performance of the Delayed Detached Eddy Simulation (DDES) turbulence model is analyzed for a nozzle blade that serves as a Pre-Swirler (PSW) in an experimental test rig. The DDES model is based on the one-equation turbulence model developed by Spalart and Allmaras. The focus is put on evaluating how well the shielding function, an essential part in the DDES model, protects the boundary layer around the PSW. This study is a part of a larger project, where future ambitions are to apply the DDES model to the whole experimental rig configuration. Preliminary simulations on the PSW showed that the shielding function did not protect the boundary layer as intended. Modification to the DDES model, proposed in the literature where a coefficient in the shielding function is altered, were therefore implemented and tested with promising results. The modification results in a better model performance for the PSW. For that reason the modified model will be considered in future simulations of the full experimental rig.