Acoustic leading-edge receptivity for supersonic/hypersonic flows over a blunt wedge

Abstract

Leading-edge receptivity to fast and slow acoustic waves of boundary layers on a cylinder–wedge geometry is investigated for a set of six different cases with Mach number ranging from 3.0 to 7.3, through direct numerical simulations of the Navier–Stokes equations. The structure of the disturbance field transmitted downstream of the shock by the imposed freestream waves is analyzed, as well as the characteristics of the wall response and its sensitivity to the angle of attack and the freestream-wave inclination angle. The results show that different postshock wave structures are formed for fast and slow acoustic waves, consisting of high-amplitude dragged and reflected waves for the fast-wave case and of low-amplitude convected waves for the slow-wave case. A good agreement is found with linear interaction theory. The wall response for fast waves shows a strong resonant amplification of mode F in the nose region and a modulated long-wavelength behavior farther downstream. In contrast, the response to slow waves shows an initial decay in the leading-edge region and an overall lower amplitude. The simulation results enable freestream disturbances, which are difficult to measure directly in experiments, to be related to wall pressure fluctuations.