ABSTRACT:  The Boundary Layer Transition (BOLT) sounding rocket flight experiment is expected to be launched in May of 2021. 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 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. Recent results that extend the DNS to laminar flow breakdown and transition to turbulence will also be discussed.

BIO:  Graham Candler is the Russell J. Penrose and McKnight Presidential Chair of Aerospace Engineering and Mechanics at the University of Minnesota. Candler and his research collaborators have developed computational methods and codes that are being used for the design and analysis of future hypersonic flight systems, including several NASA exploration missions. Recently, his work has focused on the development of more accurate simulation methods for the exploration of hypersonic flight system design space. He has published extensively in the areas computational methods, high-temperature gas modeling, boundary layer transition, and validation of computational simulations with hypersonic wind tunnel data. Candler is a Fellow of the AIAA and a member of the National Academy of Engineering.

ACDL Seminar Host: Ben Couchman