Return to Earth

PRESENT POSITION: Professor of Aerospace Engineering and Mechanics at the University of Minnesota, Minneapolis

DEGREES: B. Eng. McGill University, Montreal, Canada; M.S. and Ph.D. in Aeronautical Engineering and Astronautics, Stanford University

AREA OF RESEARCH: High temperature gas dynamics applied to Earth re-entry and planetary-probe entry aerodynamics, hypersonics, and plasma dynamics. Applications include high-speed Earth re-entry protection and manned spacecraft thermal protection systems.

LATEST ADVANCE: Work with Calspan/State University of NY at Buffalo Research Center, the world's largest hypersonic research facility, to simulate the facility to improve how it functions and, in turn, to upgrade simulations. Effort is grounded in good numerical methods and efficient parallel computing.

IMPACT ON SPACECRAFT DESIGN ENGINEERS? Developing high-fidelity tools and answers that allow them to accurately predict forces and heat transfer rates from gas flows into the re-entry vehicle structure, thus speeding the design process and optimizing configuration efficiency. Examples would be improved lift-to-drag ratios; reduced heat input to the structure, which in turn could be made lighter; and methods to alleviate off-design heat loads into a vehicle.

GREATEST CHALLENGE: The flow is not in equilibrium. As the gas particles pass through the leading edge shock wave, they are heated up to 20,000K (35,500F) and chemical reactions take place and ionized plasma forms. Such reactions continue as the flow moves along the vehicle, with reaction rates on the same order of magnitude as the fluid velocities. The flow dynamics and chemistry have to be solved along the streamlines, with reaction rates difficult to determine.

WHY COMPUTATIONAL FLUID DYNAMICS AND FLOW CHEMISTRY? I was challenged at a conference to show that it was possible to couple flow chemistry and CFD for valid results.