Blade-Vortex Interaction Airloads Prediction Using Multidisciplinary Coupling

Predictions of blade-vortex interaction (BVI) noise, using blade airloads obtained from a coupled aerodynamic, structural, and acoustics methodology, are presented. This methodology uses an iterative, loosely-coupled trim strategy for exchanging information between the computational fluid dynamics (CFD) code OVERFLOW-2 and the computational structural dynamics (CSD) and rotorcraft comprehensive code CAMRAD-II. Results are compared to the HART-II rotor baseline conditions. It is shown that this state-of-the-art CFD/CSD approach is able to capture BVI induced blade airloads and noise radiation characteristics. Predicted BVI airloads on the advancing and retreating sides agree well with the measured data. Although the BVI airloads and noise amplitudes are generally under-predicted, the CFD/CSD coupled methodology provides an overall noteworthy improvement over the lifting line aerodynamics with free-wake models typically used for CSD comprehensive analysis