Turbopropeller noise model assessment in CARMEN

The Technological Evaluator of CleanSky, which presents the context for this study, aims at estimating the environmental impact of several new concepts developed in CleanSky, including turbopropellers. Over the last years a propeller noise model has been developed and implemented in CARMEN, the acoustic module of the IESTA platform, an ONERA tool making it possible to calculate acoustic footprints around airports. This model is based on semi-empirical formula and ATR data. It is assessed against measurement data, provided by the ANIBAL (Abaissement du Niveau de Bruit des Avions Légers) measurement campaign performed in 2008, during which an innovative 5-blade propeller was tested on a small commercial aircraft. Comparisons between calculation and measurement are shown for the ANIBAL propeller as well as the reference 2-blade propeller, which is originally mounted on the aircraft. At the same time the problem of emission noise tones is addressed, since the engine frequencies partially overlap with the blade passing frequencies. The accuracy of the prediction is evaluated and ideas for improvement are discussed. This work was financed by The Technological Evaluator of CleanSky.