The Boundary Layer Transition (BOLT) sounding rocket flight experiment will be launched in May of 2020. BOLT is designed to make detailed measurements of the boundary layer state and the onset of transition to turbulence on ascent at about Mach 5 and on descent at Mach 7.5. BOLT has a complex nose geometry, highly swept leading edges and a concave surface, which challenge the validity of conventional stability analysis methods. At Minnesota we have been developing new approaches for predicting instability growth for complex geometry flows. The seminar will discuss results and progress using high-order, low-dissipation numerical methods to perform “quiet” direct numerical simulations of the BOLT flow field. The simulations reveal four different instability mechanisms; these include with a vortical disturbance associated with boundary layer roll-up on the centerline, traveling crossflow due to boundary layer distortion near the leading edge, and a complex multi-mode instability near the trailing edge. Comparisons to the available wind tunnel data will be presented. The prospects for extending the DNS to laminar flow breakdown and transition to turbulence will also be discussed.
