The influence of boundary layers on supersonic inlet flow unstart induced by mass injection

Hyungrok Do, Seong Kyun Im, M. Godfrey Mungal, Mark A. Cappelli

Research output: Contribution to journalArticlepeer-review

84 Citations (Scopus)


A transverse jet is injected into a supersonic model inlet flow to induce unstart. Planar laser Rayleigh scattering from condensed CO2 particles is used to visualize flow dynamics during the unstart process, while in some cases, wall pressure traces are simultaneously recorded. Studies conducted over a range of inlet configurations reveal that the presence of turbulent wall boundary layers strongly affect the unstart dynamics. It is found that relatively thick turbulent boundary layers in asymmetric wall boundary layer conditions prompt the formation of unstart shocks; in symmetric boundary conditions lead to the propagation of pseudo-shocks; and in both cases facilitate fast inlet unstart, when compared with thin, laminar boundary layers. Incident shockwaves and associated reflections are found to affect the speed of pressure disturbances. These disturbances, which induce boundary layer separation, are found to precede the formation of unstart shocks. The results confirm the importance of and need to better understand shock-boundary layer interactions in inlet unstart dynamics.

Original languageEnglish
Pages (from-to)679-691
Number of pages13
JournalExperiments in Fluids
Issue number3
Publication statusPublished - 2011 Sept
Externally publishedYes

Bibliographical note

Funding Information:
This work is sponsored by the Department of Energy sponsored Predictive Science Academic Alliance Program (PSAAP) at Stanford University.

ASJC Scopus subject areas

  • Computational Mechanics
  • Mechanics of Materials
  • General Physics and Astronomy
  • Fluid Flow and Transfer Processes


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