High Resolution Navier-Stokes Simulation of Rotor Wakes

Time-dependent Reynolds-averaged Navier-Stokes (RANS) simulations have been carried out on the Tilt Rotor Aeroacoustics Model (TRAM) over a wide range of collective angles. Emphasis was placed on understanding and characterizing the effects of high-order spatial accuracy and grid resolution on the prediction of figure of merit and rotor normal-force loads. Detached Eddy Simulation (DES) was also used to obtain a more realistic turbulent length scale. This hybrid RANS and Large Eddy Simulation (LES) approach resulted in the prediction of figure of merit within experimental error for a collective range of 6°≤θ≤16°. A new dynamic Adaptive Mesh Refinement (AMR) procedure was demonstrated, which revealed complex rotor wake interactions, including the emergence of vortical worms through a process of wake shear-layer entrainment into the rotor vortices and vortex stretching. Time-dependent visualization played a crucial roll in understanding the complex mechanisms involved in these flows.