Direct Numerical Simulations of Hypersonic Boundary Layer Transition on Blunt Cones
Publisher
The University of Arizona.Rights
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction, presentation (such as public display or performance) of protected items is prohibited except with permission of the author.Abstract
Direct Numerical Simulations (DNS) were carried out to investigate laminar-turbulent transition for a straight cone (7 degree half-angle) for four different cases with varying nose radii and flow conditions at Mach 6 and zero angle of attack. First a conventional Linear Stability Theory (LST) solver was used in order to determine the critical Reynolds number for amplification of second mode disturbances for each of the cases. Next, (linear) stability calculations were carried out by employing a high-order Navier-Stokes solver and using very small disturbance amplitudes inorder to capture the linear disturbance development. Contrary to standard Linear Stability Theory results, these investigations revealed a strong ``linear'' instability in the entropy layer region for a very short downstream distance for oblique disturbance waves with spatial growth rates far exceeding those of second mode disturbances. This linear instability behavior was not captured with conventional LST and/or the Parabolized Stability Equations (PSE). Secondly, nonlinear breakdown simulations were performed using high-fidelity DNS for three different cases. The DNS results showed that linearly unstable oblique disturbance waves, when excited with large enough amplitudes, lead to a rapid breakdown and complete laminar-turbulent transition in the entropy layer just upstream of the second-mode instability region.Type
textElectronic Thesis
Degree Name
M.S.Degree Level
mastersDegree Program
Graduate CollegeMechanical Engineering