Analysis of high resolution unsteady airloads for helicopter rotor blades

The study of helicopter aerodynamic loading for acoustics applications requires the application of efficient yet accurate simulations of the velocity field induced by the rotor's vortex wake. This paper summarizes work to date on the development of such an analysis, which builds on the Constant Vorticity Contour (CVC) full span free wake model. The focus here is on implementation of an airload reconstruction approach that computes high resolution airload solutions of rotor/rotor-wake interactions. The resulting analysis also incorporates improved vortex core modeling, unsteady aerodynamic effects, higher spatial resolution of rotor blade surface loading, and fast vortex wake computations. Results of validation calculations on recently-acquired model rotor data are presented. These calculations show that by employing airload reconstruction it is possible to apply the CVC wake analysis with temporal and spatial resolution suitable for acoustics applications while reducing the computation time required by at least one to two orders of magnitude relative to direct calculations. These results have also provided insight into the some of the key mechanisms in wake/blade interaction and indicate promising directions for future investigations.