A numerical study of a blunt nose with a forward-facing, cylindrical cavity was conducted for Mach 5 inviscid flow. To solve the axi-symmetrical Euler equations, we employed the Weighted ENO schemes with 5th order accuracy for spatial derivatives, and 3rd order TVD Runge-Kutta explicit method for time integration.
In this study, the characteristics of the pressure oscillation were investigated. The length of the cavity was varied, whereas the diameter was fixed. As the cavity length was increased, both the resonant frequencies and the damping decreased. The primary mode of pressure oscillation in the cavity was at the classical organ-pipe frequency. The phase difference of bow shock oscillation and the base pressure oscillation indicated that the cavity resonance drived the bow shock oscillation. The effect of artificial freestream perturbation was also studied. Sinusoidal pressure oscillation and the white noise were imposed to the freestream to find out that the cavity oscillation was excited at the acoustic resonant frequency. For the same geometry, the effects of the freesteam Mach number were investigated. As the freesteam Mach number increased, the resonant frequency was increased and the damping was decreased. To examine the effect of the cavity diameter, the diameter of the cavity was varied with L/D fixed. As the cavity diameter was decreased, the oscillations were amplified.
