Aeroacoustic Optimization

Efficient Optimization of Acoustic Liners for Engine Noise Reduction

Due to the exposed radiation from an aircraft flying over urban areas, the air-traffic noise affects a large number of people and became a significant environmental problem. The situation became more severe due to the rapid increase of air-traffic in recent years. In fact, the growth of an airport is found to be limited mainly by the public acceptance of the air traffic with respect to the noise emission. Due to the effects of noise on environment and health, aircraft noise reduction has been an important objective of the national and European research activities.

As far as the noise emission is concerned, the noise generated by the turbofan aero-engines is still the major source of noise at landing and take-off. Therefore, reducing engine noise is one of the important goals in the turbofan engine design. Today, the passive treatment using acoustic liners in aero-engines is a standard technique. The best ratio of weight and noise reduction is currently achieved by generalized Helmholtz resonator panels. The third generation of such panels consist of a rigid back plate, cavities and a perforated face sheet. With the development of optimized CAA methods and impedance modelling, it has become possible to simulate the effect of these acoustic liners on the sound level for a given acoustic source.

In this project we aim at developing an efficient optimization framework for the numerical optimization of acoustic liner parameters. These kind of optimization problems are characterized by the large number of design parameters as well as the high numerical cost of CAA simulations caused by the unsteadiness of the sound propagation phenomena. Combining adjoint technology with the advanced gradient-based numerical optimization methods, it is possible to find the optimum distribution of liner parameters that gives the best acoustic performance for a given engine design.

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Partners: CFD GmbH Berlin

Funded by BMWi LuFo Förderlinie

Contact: Dr. Emre Özkaya, Dipl. Ing. Junis Abdel Hay and Prof Nicolas R. Gauger.