Validation and Analysis of Aeroelastic Simulations of the UH-60A Rotor from Pre- to Post-stall Flight Conditions

Abstract

Recently aeroelastic simulations of rotors in dynamic stall conditions based on a weak coupling between CFD (Computational Fluid Dynamics) and CA (Comprehensive Analysis) codes have demonstrated their prediction capabilities with good agreement with experimental data, despite the high level of complexity of this phenomenon. These recent studies resulted from a long-term effort to define the requirements, in terms of methods and models, necessary to capture of the complex physics of dynamic stall in rotor environment. However, these previous studies were performed on single test points. In this paper a range of six flight conditions of the UH-60A rotor from pre- to post-stall conditions with three different numerical approaches was examined. This approach permits not only the validation of the numerical methods on a larger set of data, but it provides a thorough analysis of the ability of the numerical methods to predict the onset of stall as the rotor thrust progressively increases. The numerical results show very good agreement on airloads, trim control angles and rotor power. More discrepancies are observed in structural loads although the global trend is captured. The flowfield visualizations from the simulations give a better insight into several regions of flow separation, their evolutions as the rotor thrust increases and the role of Blade Vortex Interaction (BVI) in the trigger of the different stall events.