Three-Dimensional Turbulent Boundary Layer Flow on Roughness Strip of Finite Width.

摘要

Described are the results of an experimental study of a well developed,turbulent boundary layer on a smooth,flat surface encountering an area of much rougher surface. The roughened area is a strip with its length extending in the direction of the mean flow but of finite width in the surface direction normal to the flow. The resulting three-dimensional flow is found to differ significantly from previously studied cases involving step changes in roughness of infinite extent in the direction normal to the flow. Extensive experiments are reported in a wind tunnel having a length of nearly 100ft with a boundary layer thickness of the order of 18-20in. Pitot tube and hot-wire anemometer measurements were made of mean velocity and Reynolds stress quantities throughout the flow field. Secondary flow components were measured by a new x-wire technique. (Modified author abstract)