Coupled and Trimmed Aerodynamic and Aeroacoustic Simulations for Airbus Helicopters' Compound Helicopter RACER

In recent years, various helicopter manufacturers increasingly have been focusing on the development of new high-speed rotorcraft configurations, one of them being the compound helicopter RACER (rapid and cost-efficient rotorcraft) of Airbus Helicopters (AH). However, these new configurations encounter new aeromechanic challenges, in terms of aerodynamic interactions, flight mechanics stability, rotor dynamics, or aeroacoustic noise emission, to name only a few. To support AH at the minimization of risk of RACER's first flight, the Institute of Aerodynamics and Gas Dynamics provides high-fidelity coupled and trimmed aerodynamic and aeroacoustic simulations of the complete helicopter by the application of a multidisciplinary tool chain. In its first part, the work focuses on the description of this advanced tool chain and on important features for the analysis of this new configuration. In the second part, exemplary simulation results for a hover and a high-speed cruise flight condition are shown, and the main aerodynamic interactions between the different components are identified. As expected for this configuration, numerous interactions are found for both flight cases, e.g., main rotor–propeller interaction in hover or main rotor–wing interaction in high-speed flight. Finally, aeroacoustic results are shown for hover with a close look at the propellers' contribution.