Time-Averaged Characteristics in Turbulent Channel Flow with Injection

Abstract

An experimental study is carried out on a fully developed turbulent channel flow with uniform injection through a porous wall at five injection rates. Attention is mainly paid to a self-preserving region of such flows. The fluctuations of streamwise velocity, as well as the mean velocity profiles, are measured by means of a hot-wire anemometer. Mean velocity decreases in the region of y/h< 0.15 and increases in the core region. A similarity of the velocity defect profile is observed when the velocity defect is normalized with the outer scales. Turbulence intensity increases with increasing injection rate except very near the wall. Moreover, the relationship between van Driest's damping factor and nondimensional injection velocity, and the method of determining the friction velocity are clarified.