Iemma U., Diez M., Marchese V.

The aim of the present work is to describe a novel approach for including of community noise considerations, in the conceptual design of aircraft. Specifically, a Multidisciplinary Design Optimization (MDO) framework is coupled to a sound–comparison algorithm, in order to lead the configuration to meet some “sound-matching” criteria. The availability of such a tool makes it possible the development of new aircraft concepts, whose acoustic emissions are as close as possible to a “target sound”. This point of view differs from the classical “noise-level-abatement” approach, and is catching the attention of the designer, due to the current trends of the aeronautic civil transportation system. Indeeed, the air traffic is experiencing, nowadays, an enormous growth rate, especially in European countries. The commercial success of the low-cost philosophy increased the number of passengers and the frequency of flights. As a consequence of this, the number of citizens annoyed by noise due to aircraft operations is rapidly increasing. To reduce the community annoyance, the transportation authorities are progressively tightening the regulation constraints by imposing to the airliners lower emission levels and increasing the charges for “noise taxes”. In this scenario, the designers are facing with an extremely challenging problem, being the noise reduction required in the next decade very difficult to meet with the current configurations, thus needing the development of highly innovative concepts. Here, suitable noise-source models are introduced in the MDO framework, and a measure of the similarity of the aircraft noise emission with a given “target sound” is evaluated. To accomplish this, a sound-similarity index is defined as the L-infinity-norm of the spectral difference. Preliminary results show that the influence of this new design constraint is not negligible, leading the optimization process towards unusual solutions.