Instability

Prediction and control of the hypersonic boundary-layer transition from a laminar to a turbulent state are vital to developing future hypersonic systems – capable of reaching at least Mach 5, or approximately 3,800 mph.

The Kelvin–Helmholtz instability is solved to study shear-driven turbulent flows. Efficacy and accuracy of several Riemann solvers for WENO schemes are investigated. Eddy resolving properties and turbulence statistics are studied.

WENO schemes with Roe solver are more accurate than all other methods tested. High-order numerical techniques are required to capture small-scale vortical flow structures.

The appearance of instability waves near the nose region and the receptivity of the boundary layer with respect to slow mode acoustic waves are investigated. Computations confirm the stabilizing effect of nose bluntness and the role of the entropy layer in the delay of boundary-layer transition.