Title

Numerical Investigation of Variable Transpiration Cooling Effectiveness in Laminar and Turbulent Flows for Hypersonic Cruise Vehicles

Abstract

The thermal management of hypersonic air-breathing vehicles presents formidable challenges. Reusable thermal protection systems (TPS) are one of the key technologies that mustbe improved in order to use hypersonic vehicles as practical, long-range transportation systems. The active cooling systems, such as transpiration cooling,have to be considered foraffordable,long duration flights to achieveefficient temperature reduction and coolant mass saving.With this technique, it is important to understand the physics that characterize the boundary layer and its interaction with the vehicle-s surface. This paper investigatesthe effectiveness of a variable-velocitytranspiration strategy for fully laminar, transitional, and fully turbulent flowsover a 2-D blunt bodywith a cylindricalleading edge and a wedge region. Thetransitional flow cases areevaluated for a range of transitionlocations to see the influence of this parameter on the variable transpiration strategy introduced. For all flow typespresented in this paper, asaw-tooth wall velocity distribution(variable transpiration strategy) iscompared to a uniform-velocitytranspiration approach. An equalamountof coolantusage has been imposed in order to compare the cooling effectivenessbetween bothstrategiesfor variousflow types in different regions of the body. The results show that the uniform-velocitytranspiration allows areduction of 68% in the stagnation point heat flux and 77% for variable-velocity transpiration with respect to the no-transpiration casein both laminar and turbulent flow cases. The computational results show that the efficiency of the transpiration cooling is much higher in laminar flowcompared to turbulent flow in regions downstream of the stagnation point.In such regions, for turbulent flows, the amount of total coolant must be increased by 110% (factor of roughly 2) to match the cooling efficiency observed in laminar flows. In addition tothe analysis of cooling effectiveness, the thermal response of TPS material with the variable transpiration strategy isalsoinvestigated for both fully laminar and fully turbulent flows

Meeting Name

51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition

Department(s)

Mechanical and Aerospace Engineering

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2013 American Institute of Aeronautics and Astronautics (AIAA), All rights reserved.


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