Hybrid RANS/LES of an isolated engine nacelle with side wind using an unstructured CFD solver

The present work focuses on the scale-resolving numerical simulation of an isolated jet-engine intake in presence of side wind. The computation was carried out with the DLR TAU code within the framework of the Rolls-Royce funded project FaNcI (Fan-Nacelle Integration) and relied on advanced numerical techniques recently developed as part of the DLR project VicToria (Virtual Aircraft Technology Integration Platform). The goal of the present work was the simulation of the intake flow in off-design condition with high crosswind: a partially separated flow where the flow reattachment takes place in the proximity of the hypothetical fan location. A hybrid RANS/LES method based on the Improved Delayed Detached-Eddy Simulation (IDDES) was combined with the low-dispersion low-dissipation numerical scheme (LD2). In particular, a hybrid formulation of the LD2 scheme ensured robustness also in regions of complex grid topologies and flow phenomena involving strong gradients. The result validation is based on experimental measurements of the flow distortion inside the engine inlet. From the final picture the need for scale-resolving turbulence simulation and the advantage of a specific numerical scheme clearly emerge.