Assessment of CFD/CSD Analytical Tools for Improved Rotor Loads

Comparisons of many analysis codes have been made during the course of the UH-60 Airloads Workshops. However, most comparisons involve only a small number of codes, and modeling assumptions are not consistent among all researchers. The Improved Prediction of Rotor Loads TAJI project, funded by the Vertical Lift Consortium (VLC), was initiated in part to perform a rigorous comparison of coupled solutions with the most widely used CSD and CFD codes. Careful comparisons of the structural models were made, and small modeling differences were eliminated. Loosely coupled simulations were made for UH-60A flight and wind tunnel test cases, in addition to other industry helicopter configurations. Flap bending and blade torsion loads are well predicted for all of the cases studied, while edgewise bending and pushrod loads tend to contain higher harmonic load content, which is less well predicted by the analysis. The various code combinations studied yield very similar load predictions when identical modeling assumptions are made. However, certain gaps remain in terms of correlation with test data.