Scales of Turbulence During Boundary Layer Transition Under Steady and Unsteady Flow Conditions
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Copyright © 1999 by ASME. Boundary layer hot-wire measurements are analyzed for scales of turbulence during transition. Experimental dati from two test sections (one consisting of a curved plate and the other consisting of five blades in a turbine C0'4-flit.) are used in the current analysis. Unsteady wake flow conditions are simulated using circular rods upstream of the test section and the boundary layer measurements are taken for different wake passing frequencies. Recent developments in wavelet analysis are used to quantify the energy corresponding to different scales of turbulence in the signal. Also, dominant scales having the maximum energy content in the velocity signal are enacted to get the macroscopic picture during boundary layer transition. A continuous increase in scale' activity during transition is seen for the steady flow data, whereas for unsteady flow cases the energy is dominant for higher frequencies as the wake passing frequency increases. This scale information is essential for improving transition models and validating CFD codes.
author list (cited authors)
Chakka, P., & Schobeiri, M. T.