First and mack-mode instabilities in a flat-plate boundary layer at mach 4

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Boundary layer stability experiments are performed in a Mach 4 quiet wind tunnel on a flat plate. Clusters of surface-mounted, high-frequency pressure transducers are installed at two locations on the model. Transducer clusters allow the computation of cross-spectra and the determination of the phase speeds and wave angles of passing boundary-layer waves. At an edge Mach number of 4, the coexistence of Mack’s first and second modes is of particular interest. Peaks in the autospectral densities provide weak and inconsistent evidence of unstable waves within frequency bands relevant to either mode of interest. Cross-spectral densities show high coherence at frequencies associated with the first mode. Wave angles appear to match well with those predicted for the first mode, while other propagation information matches poorly, likely due to shortcomings in the analysis tools in dealing with low signal to noise ratio situations.

Original languageEnglish (US)
Title of host publicationAIAA Scitech 2020 Forum
PublisherAmerican Institute of Aeronautics and Astronautics Inc, AIAA
ISBN (Print)9781624105951
StatePublished - 2020
EventAIAA Scitech Forum, 2020 - Orlando, United States
Duration: Jan 6 2020Jan 10 2020

Publication series

NameAIAA Scitech 2020 Forum
Volume1 PartF


ConferenceAIAA Scitech Forum, 2020
Country/TerritoryUnited States

ASJC Scopus subject areas

  • Aerospace Engineering


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