Modelling and Control of Aeroacoustic Noise

The reduction of aeroacoustic noise is a major engineering challenge that affects a wide range of industries from air transport to wind energy. For instance, noise pollution for communities near airports is a major constraint on further growth of air transport traffic. In particular, when landing gears are being deployed during the approach phase of flight they become the main contributor to the airframe noise. Similarly, the noise emitted from wind-turbine blades is limiting further spread of onshore wind-farm due to public concern about noise pollution. The noise emitted from the blades is predominately aerodynamic and is generated when a turbulent boundary layer interacts with a trailing-edge of a blade. Reducing the noise level while maintaining aerodynamic performance is a challenge today and it is likely to be more important in the future.
This talk will focus on enhancing, predicting and controlling aeroacoustic performance. The first part of the talk will discuss the noise generation associated with bluff bodies, such as circular, and the application of flow control for noise reduction. Experiments were performed in the University of Southampton’s open jet anechoic facility and closed-loop aerodynamic wind-tunnel to investigate the effect of blowing circumferential angle and strength and found that noise can be reduced when flow-control is applies under optimal conditions. The second part of the talk will discuss further development of airfoil self-noise prediction model. This work extends previously published TNO-Blake semi-infinite broadband airfoil self-noise model to incorporate finite chord noise radiation Amiet model with recent improvements in modelling of boundary-layer parameters. These results demonstrate that aerodynamic noise of NACA-0012 airfoil section can be predicted with less than 2dB while avoiding parameter tuning. Furthermore, the TNO-Amiet model captures the measured oscillation in both far-field spectra and directivity patterns. The results of these studies could be applied in the future to guide industry to improve both aerodynamic and aeroacoustic performance.