Effects of shock-tube cleanliness on hypersonic boundary layer transition at high enthalpy

Joseph S. Jewell, Nicholaus J. Parziale, Ivett A. Leyva, Joseph E. Shepherd

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

A study has shown that an improved cleaning procedure in a hypervelocity shock tunnel improves the repeatability of transition measurements, demonstrating the need for researchers using impulse facilities for hypervelocity boundary-layer instability and transition research to operate the facility in a manner least likely to introduce particulate to the test flow. FLDI (boundary-layer density disturbances) and heat transfer (surface-mounted heat transfer thermocouples) results were compared before and after a stringent cleaning regimen was implemented. Before the implementation of the cleaning regimen, unpredictable turbulent spots were observed in both FLDI and thermocouple data at locations uncharacteristic of natural transition. It is believed that it is likely these turbulent spots are the result of bypass transition initiated by particulate striking the model surface. A statistical analysis of the correlation of tunnel parameters to transition location indicates that the coefficient of determination was significantly increased after the implementation of the cleaning regimen. This increase in the coefficient of determination is consistent with more repeatable transition locations and flow quality. The new cleaning regimen makes it possible to systematically characterize transition locations on the test article in a repeatable manner by carefully selecting run conditions.

Original languageEnglish
Pages (from-to)332-338
Number of pages7
JournalAIAA journal
Volume55
Issue number1
DOIs
StatePublished - 2017

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