Effect of tripping on hypersonic turbulent boundary-layer statistics

Owen J.H. Williams, Alexander J. Smits

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


The effect of varying three-dimensional, cylindrical post-type trip size on the mean and turbulent velocity profiles of a Mach 7.6 turbulent boundary layer is examined using particle image velocimetry. It is shown that the effect of underand overtripping is to amplify the wake component of the mean velocity profile and outer-layer turbulence intensity, confirming trends from incompressible flow. Such results indicate that overly aggressive tripping introduces artificial large-scale turbulence that requires longer downstream distances to decay. For the current experiment, adequate tripping was obtained for trip sizes between 1.7 and 2.3 times the laminar boundary-layer displacement thickness at the trip, δtr, with the optimum size approximately 2.3 δtr. The wake strength for the optimally tripped cases followed the correlation of Fernholz and Finley (AGARDograph 253, Neuilly sur Seine, France, 1980) at the same Reynolds number, providing a good indicator for under- or overtripping. These results confirm that compressible boundary layers mimic incompressible trends but require larger trip sizes and have increased sensitivity, making a boundary layer free from initial conditions harder to achieve.

Original languageEnglish (US)
Pages (from-to)3051-3058
Number of pages8
JournalAIAA journal
Issue number9
StatePublished - 2017

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering


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