Numerical modelling of fluid-induced noise from lifting surfaces at moderate Reynolds numbers

Fluid-induced noise from lifting surface flows occurs in a wide variety of industrial applications and, despite decades of research, there are still many open questions relating to the underlying physics of how different flows produce particular acoustic signatures. Predicting fluid-induced noise is challenging and requires a detailed understanding of the underlying fluid flow. At moderate Reynolds numbers, the transitional nature of the flow makes the acoustic field very sensitive to small changes in the flow conditions, making predictions particularly difficult. This thesis presents a numerical study of fluid-induced noise over lifting surfaces. A hybrid aero-acoustic model is developed that is capable of resolving the acoustic field resulting from the turbulent flow over an arbitrary body or bodies. The methodology leads to a flexible and robust model that allows for both the fluid and acoustic fields to be resolved simultaneously on separate, partially overlapping domains, allowing for the separation of turbulent and acoustic scales to be handled in an efficient manner. The model is used, together with large eddy and direct numerical simulations, to investigate the fluid dynamics and fluid-induced noise of flows over lifting surfaces at moderate Reynolds numbers (o 10^5). The acoustics of finite and infinite span lifting surfaces are investigated, with a particular focus on trailing edge noise and its relationship to a transitional boundary layer. Multi-body interaction noise is also considered, with results comparing favourably with experimental data, providing a high degree of confidence in the predictive capabilities of the model.