Semi-empirical Investigation of the Effect of Finlet on the Turbulent Boundary Layer Trailing Edge Noise

The study of turbulent boundary layer trailing edge noise as one of the most important aerodynamic sound generation mechanisms is a fundamental issue in design and production of equipment with minimum noise. In the present study, the utilization of finlets as a turbulent boundary layer trailing edge noise control technique is investigated. For this purpose, a flat-plate model, equipped with surface pressure transducers has been designed and built and the main parameters of trailing edge noise including the surface pressure spectra, the spanwise length scale, and eddy convection velocity in the trailing edge region have been measured. Moreover, in order to study the structure of the boundary layer flow downstream of the surface treatments, a single hot-wire anemometer has been used. The results showed that the presence of finlets leads to a significant reduction in the surface pressure spectra at all frequency ranges except for frequencies close to the maximum surface pressure spectrum. Furthermore, passing the flow structures through the finlets, although did not create significant changes to the spanwise length scale at high frequencies, however, they have led to an increase at low to mid frequencies. Finally, the Amiet-Roger model has been used to evaluate the changes in far field trailing edge noise due to the presence of the finlets and the results show the effectiveness of finlets in reducing trailing edge noise over a wide range of frequencies.