Experimental study of a threedimensional sheardriven turbulent boundary layer with streamwise adverse pressure gradient
Abstract
The effects of a strong adverse pressure gradient on a threedimensional turbulent boundary layer are studied in an axisymmetric spinning cylinder geometry. Velocity measurements made with a threecomponent laser Doppler velocimeter include all three mean flow components, all six Reynolds stress components, and all ten tripleproduct correlations. Reynolds stress diminishes as the flow becomes threedimensional. Lower levels of shear stress were seen to persist under adverse pressure gradient conditions. This low level of stress was seen to roughly correlate with the magnitude of crossflow (relative to free stream flow) for this experiment as well as most of the other experiments in the literature. Variations in pressure gradient do not appear to alter this correlation. For this reason, it is hypothesized that a threedimensional boundary layer is more prone to separate than a twodimensional boundary layer, although it could not be directly shown here. None of the computations performed with either a Prandtl mixing length, kepsilon, or a LaunderReeceRodi full Reynoldsstress model were able to predict the reduction in Reynolds stress. A 1.2 MB IBMformat floppy diskette is included.
 Publication:

NASA Ames Research Center Technical Report
 Pub Date:
 May 1990
 Bibcode:
 1990ames.rept.....D
 Keywords:

 Pressure Gradients;
 Reynolds Stress;
 Shear Stress;
 Three Dimensional Boundary Layer;
 Turbulent Boundary Layer;
 Two Dimensional Boundary Layer;
 Velocity Measurement;
 Cross Flow;
 Free Flow;
 KEpsilon Turbulence Model;
 Laser Doppler Velocimeters;
 Mixing Length Flow Theory;
 Fluid Mechanics and Heat Transfer