Collaborative Research: Extreme Thermal Transport Events in Supersonic and Hypersonic Shock Wave-Turbulence Interactions

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High-speed flows near or exceeding the speed of sound causes intense aerodynamic heating, which requires sophisticated thermal protection systems. The high temperatures combined with extreme flow events, such as shock waves and turbulence, reduce the life of propulsion devices, such as gas turbine engines, high performance aircraft aero-engines, scramjets, rockets, lift-off and reentry vehicles, among others. The project will address complex thermal transport processes during the interactions of shock wave and turbulence with the goal of enabling safer and more reliable aero-propulsion engines. Fundamental understanding will be promoted, along with training, teaching, and learning by means of parallel education/outreach components, such as incorporation of findings in graduate education, and presentations in symposia and conferences. Women, minority students, and undergraduate students will also participate, as well as both teachers and students from local high schools. This project seeks to improve the understanding of thermal turbulence transport by considering: (a) effects of shock wave mode, angle, orientation, and strength, and the sources and modes of shock wave unsteadiness which alter thermal transport and surface heat transfer, (b) the means whereby shock wave unsteadiness alters and propagates into subsonic boundary layer regions to affect near-wall thermal transport mechanisms and surface heat transfer, (c) effects of the strength and relative size of shock wave induced separation on thermal transport, (d) effects of shock wave compression heating, viscous friction heating, and conversion of kinetic energy to internal energy on thermal transport, and (e) resulting alterations to turbulence and scalar fluxes, second order turbulent quantities, and coherence and time lag distributions. Unsteady motions of different types of shock waves and unsteady, spatially-varying surface heat transfer and thermal transport will be considered through a coordinated experimental-computational study. A newly developed supersonic wind tunnel system will be employed, along with large eddy simulations, to provide detailed flow and thermal field characteristics. Crucial causal relationships will be clarified through understanding of: (i) associated thermal transport characteristics, (ii) spatially-dependent and frequency-dependent coherence and time lag between events at different flow conditions, (iii) highly-resolved experimental visualizations of unsteady flow features from which quantitative flow information will be determined, and (iv) spatio-temporal flow and thermal field-data from numerical predictions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.