Back-scattering correction and further extensions of Amietʹs trailing-edge noise model. Part II: Application

The analytical model of the trailing-edge noise of an airfoil derived in the first part of this study is assessed by first comparing the predictions with alternative analytical and numerical computations found in the literature. Comparisons are also made with experimental data. The data are either taken from the literature or collected in a series of new experiments run in open-jet anechoic wind tunnels. Several configurations have been investigated, ranging from a flat plate to symmetric and cambered, thick and thin airfoils, at various angles of attack triggering various flow regimes at different Reynolds numbers. The comparisons address the distribution of the far-field radiated noise both in frequency and radiation angle. The transfer function between the wall-pressure fluctuations in the vicinity of the trailing edge and the noise radiated in the far field is found experimentally to be roughly independent of the flow conditions encountered on the airfoil, as far as the mean flow remains attached. The good agreement of the present predictions with both the measurements and the alternative theories not only emphasises the relevance and accuracy of the model but also stresses the effect of the finite chord length in the noise generation and radiation mechanisms. Moderate airfoil camber and angle of attack are shown to be of secondary importance on the noise radiation, even though they fully determine the sources of the noise through the flow field. All comparisons make the model accurate enough provided precise flow data are available.