Characteristics of aerodynamic noise radiated from a forward facing step with an incoming turbulent boundary layer

Abstract

In this study, aerodynamic noise generates from forward step flow with different flow velocities U0 and step heights H were measured to investigate the characteristics of high-frequency wind noise generated from the Forward-Facing Step. The flow velocity was set to 0~50 m/s and the step height to H = 15, 30 and 45 mm. The aerodynamic noise was converted into sound pressure spectra by FFT to investigate their characteristics. To investigate the influence of the boundary layer thickness δ and step height H on the shear layer of the step, correlation measurements were performed on the shear layer to estimate the vortex scale. The results show that the high-frequency aerodynamic noise has a characteristic peak that is independent of the flow velocity. It is also confirmed that vortex scales which are nondimensionalized by step height generated in the shear layer at H/δ = 2 and 3 is similar.