Thermo-fluid-dynamics of a complex fluid flow

Abstract

The main purpose of the present work is to find connections between turbulent statistics of a jet in cross-flow and the convective heat transfer over the wall the jet issues from. The velocity field and the flow statistics are evaluated by means of the Particle Image Velocimetry (PIV) technique. The heated-thin-foil technique associated to the detection of temperature by means of an infrared scanning radiometer is used to perform convective heat transfer measurements. The study is restricted to jet to free stream velocity ratios ranging from 1 to 5 and to a Reynolds number equal to 8000. The vortical structures originating from the interaction of the jet with the cross-flow are visualized and the mean and instantaneous velocities are measured in the jet symmetry plane and in planes normal to the jet axis. For most velocity ratios, a linkage appears to be found between the heat transfer and the in-plane turbulent kinetic energy measured close to the wall. Furthermore, the counter rotating vortex pair, which is bound to the lee surface of the jet, has a shape which is strongly dependent on the velocity ratio; this parameter has a strong influence also on the heat transfer in the vicinity of the jet exit section.