Application of Adaptive Mesh Refinement Technique in Helios to Blade-Vortex Interaction Loading and Rotor Wakes

The Helios high-fidelity rotorcraft simulation software was used for CFD/CSD coupling of the HART II rotor in descending flight. Cartesian-based unsteady adaptive mesh refinement (AMR) was applied in the off-body flow field, and the results were compared with the measured data and Overflow-2/CAMRAD II results. The comparisons were made for the blade frequencies, blade torsion, trim, airloads, wake positions, and the vorticity field. Helios results showed predictions in various disciplines that were generally comparable to existing state-of-the-art CFD/CSD analysis results. Rotor wake positions on the advancing side were comparably predicted between Overflow-2/CAMRAD II and Helios, and their errors were within 1.3 chords. The predictions on the retreating side were largely improved. Adaptive mesh refinement (AMR) solution was successfully demonstrated to preserve vorticity well downstream automatically. However, the computational cost saving with AMR was minimal. A key motivation for AMR appears that it can automatically detect and refine to the wake features.