The state of art at the beginning of the CONCERTO project regarding the noise prediction of the RACER’s lateral rotors corresponds to what has been proposed in the CS2 NACOR project. The methodology proposed by ONERA, which is the basis for the activities in CONCERTO to predict lateral rotors noise, is the following:
• the aerodynamic code PUMA computes the noise source by taking into account interactions with the main rotor’s downwash and the wings’ wake using a perturbation field computed separately by a CFD code,
• using those noise sources, the direct acoustic field is computed by the KIM code,
• the acoustic field scattered by the RACER’s fuselage is obtained thanks to a BEM code.
The CONCERTO project has gone beyond this approach. First of all, the methodology is now fully integrated in a computational chain, allowing easier and faster predictions. Also, DLR has developed a Reduced Order Model (ROM) strategy to provide perturbation fields derived from CFD. Using CFD simulations for a few, carefully selected, flight conditions, the ROM provides perturbation data for PUMA for a wide range of flight conditions without additional time consuming CFD simulations. Other improvements are listed here after:
• noise predictions during a maneuver,
• inclusion of the main rotor in the PUMA simulations,
• development of analytical models to capture propeller interactions with wings and main rotor in PUMA calculations,
• fast predictions of the acoustic scattered field using simplified approaches.
Several impacts have been identified, at the environmental, industrial and societal levels by:
• mitigating the noise footprint of a compound helicopter,
• strengthening the European Competitiveness of the aeronautical industry,
• increasing the range and speed for rescue, emergency and passenger transport.
These impacts are related to the fact that this project has provided AH with the tools for designing the best possible compound rotorcraft in terms of noise emission in a shorter period of time. This is actually the case, since AH’ engineers are now able to perform their own noise prediction using the CONCERTO chain. Another expected impact is the enhancement of research and innovation capacity. Compound helicopters, like the RACER, are an actual challenge for the aeronautical research community. The improvements achieved in the CONCERTO project will definitely help in the prediction of aerodynamics and acoustics installation effects of next generation aircraft.
