Ndaona Chokani

TL;DR: In this paper, boundary-layer measurements were conducted over a flared cone in a quiet wind tunnel and the results suggest that the second mode is the dominant mode of instability, compared well with linear stability theory in the linear stability regime.

TL;DR: In this article, the effect of thermal and chemical nonequilibrium on stability is shown to depend on the disturbance mode and the frequency and spatial ampli® cation of disturbances that may lead to boundary layertransition on cold wall and adiabaticat plates.

TL;DR: In this article, the stabilization of the second-mode disturbance using a passive, ultrasonically absorptive coating (UAC) of regular microstructure is studied using bispectral analysis, which consists of hot-wire measurements made in artificially excited wave packets that are introduced into the hypersonic boundary layer on both solid and porous surfaces.

Abstract: The hypersonic flow over a cavity is investigated. The time-dependent compressible Navier-Stokes equations, in terms of mass averaged variables, are numerically solved. An implicit algorithm, with a subiteration procedure to recover time-accuracy, is used to perform the time-accurate computations. The objective of the study is to investigate the effects of Reynolds number and cavity dimensions. The comparison of the computations with available experimental data, in terms of time mean static pressure, heat transfer, and Mach number show good agreement. In the computations large vortex structures, which adversely affect the cavity flow characteristics, are observed at the rear of the cavity. A self-sustained oscillatory motion occurs within the cavity over a range of Reynolds number and cavity dimensions. The frequency spectra of the oscillations show good agreement with a modified semi-empirical relation.

TL;DR: In this article, a small jet placed within the cavity just below the front lip was used to force the shear layer with different amplitudes and frequencies, which was successful in reducing the amplitude of the oscillations.