Events Calendar

AME Seminar

Speaker: Joanna Austin, Caltech

Talk Title: Hypervelocity Spherically-Blunted Cone Flows in Mars Entry Ground Testing

Abstract: The intent to launch larger vehicles in future Mars missions increases the requirements for ground testing in the high-stagnation enthalpy environment encountered by the vehicle during the hypersonic phase of entry, descent and landing. During atmospheric entry, strong shock compression and high post-shock temperatures lead to significant chemical dissociation and vibrational excitation in the shock layer in front of a sphere-cone capsule, particularly near the stagnation region. For Mars missions, accurate thermochemical modeling of carbon dioxide, a principal component of the atmosphere with complex vibrational energy exchange, is particularly important. We examine the shock layer over sphere and spherically-blunted cone geometries through reacting Navier-Stokes simulations and experiments in two facilities capable of high-stagnation enthalpy, hypersonic flows simulating Mars planetary entry conditions: the T5 Reflected Shock Tunnel and the Hypervelocity Expansion Tube. A recently-developed unified model for sphere and sphere-cone behavior is first verified for high-stagnation enthalpy CO2 flows through simulations with thermal and chemical nonequilibrium. Shock standoff distance measurements in both facilities are in good agreement with model predictions. The need to account for the divergence of the streamlines in conical nozzles is highlighted and an existing model is extended to account for changes in shock curvature between parallel and conical flow. The contributions of vibrational and chemical nonequilibrium to the stagnation line density profile are quantified using the simulation results comparing three chemical kinetic models. Experimental measurement of fore- and aftbody MWIR radiation will also be discussed.

Biography: Joanna Austin is Professor of Aerospace at the Graduate Aerospace Laboratories, California Institute of Technology. She received B.E. (Mechanical and Space Engineering) and B.Sc. (Mathematics) degrees from the University of Queensland, Australia, and M.S. followed by Ph.D. (2003) degrees in Aeronautics from the California Institute of Technology. Austin then joined the faculty in the Aerospace Engineering department at the University of Illinois, becoming Associate Professor and Willett Faculty Scholar, before moving back to Caltech in 2014, where she is a co-PI in the Caltech Hypersonics Group. Austin's research is focused on fundamental problems in reactive, compressible flows across a broad range of applications including hypervelocity flight, supersonic combustion and detonation, bubble dynamics, and explosive geological events.

Host: AME Department

More Info: https://usc.zoom.us/j/99638511716

Webcast: https://usc.zoom.us/j/99638511716

WebCast Link: https://usc.zoom.us/j/99638511716

Audiences: Everyone Is Invited

Contact: Tessa Yao

Event Link: https://usc.zoom.us/j/99638511716