Licentiate seminar

Transitional boundary layers caused by free-stream turbulence

Defendant Main Advisor Extra Advisor Date
Shahab Shahinfar Jens Fransson Henrik Alfredsson 2011-06-09

Johan Westin, Hägglunds AB

Evaluation committee


The present measurement campaign on the free-stream turbulence (FST) induced boundary layer transition scenario has provided a unique set of experimental data, with potential to enhance the understanding of the effect of the free-stream turbulence characteristic length scales on the transition location and not only the turbulence intensity, which has been the focus in most previous studies. Recent investigations where the turbulence intensity has been kept essentially constant, while the integral length scale has been changed, show that the transition location is advanced for increasing length scale. However, the present data show that the integral and Taylor length scales of the FST have a relatively small influence on the transition location as compared to the turbulence intensity and data analyses are now directed towards enhanced understanding of how the different parts of the incoming energy spectrum affects the energy growth inside the boundary layer.
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