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National_Catalogues: Transition Delay in Hypervelocity Boundary Layers by Means of CO2/Acoustic Instability Interactions

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Title

Transition Delay in Hypervelocity Boundary Layers by Means of CO2/Acoustic Instability Interactions

Identifier

ADA500717

STOAbstractExternal

A novel method to delay transition in hypervelocity flows over slender bodies by injecting CO2 into the boundary layer of interest is investigated. The results presented here consist of both experimental and computational data. The experimental data was obtained at Caltech's T5 reflected shock tunnel, while the computational data was obtained at the University of Minnesota. The experimental model was a 5 degree sharp cone, chosen because of its relevance to axisymmetric hypersonic vehicle designs and the wealth of experimental and numerical data available for this geometry. The model was instrumented with thermocouples, providing heat transfer measurements from which transition locations were determined and the efficacy of adding CO2 in delaying transition was gauged. For CO2/N2 freestream blends without injection, the transition Reynolds number more than doubled for mixtures with 40% CO2 mole fraction compared to the case of 100% N2. For the cases with injection, shadowgraph visualizations were obtained, allowing verification of the injection timing. The computations provide encouraging results that for the injection schemes proposed CO2 is reaching high enough temperatures to excite vibrational modes and thus delay transition.

STOAuthorExternal

AIR FORCE RESEARCH LAB EDWARDS AFB CA Leyva, Ivett A., Laurence, Stuart, Beierholm, Amy W., Hornung, Hans G., Wagnild, Ross, Candler, Graham

STOClassificationExternal

STOKeywordsExternal

BRIEFING CHARTS, WUAFRL23070725

STOPublisher

USA

Language

English

STOReportSource

http://www.dtic.mil/docs/citations/ADA500717

Published

12/8/2008