Measurement of turbulent diffusion field behind a line heat source in a homogeneous shear flow

Abstract

Turbulent diffusion behind a line heat source immersed in a nearly homogeneous shear flow is investigated. Test section of the wind tunnel is divided into 15 equal width channels equipped with adjustable internal flow resistances for the production of homogeneous shear flow. A combination of X-type hot wire for the measurement of velocity fluctuations and a cold wire for the measurement of temperature fluctuations has been devised to simultaneously obtain the cross correlations between the velocity and temperature fluctuations. The results show that all the distributions of velocity and scalar field are shifted toward the low velocity region of the homogeneous shear flow. The integral scales for velocity and scalar are different from each other in the shape of profiles so that the time scale ratio R does not remain constant. And the distributions of mean and fluctuating temperatures collapsed into a Gaussian curve by normalizing with mean half width and peak temperature.