Movement of impingement heat transfer by a single circular jet with a confined wall

Impingement heat transfer and flow in the radial and circumferential directions by a single circular laminar jet in a flow passage with a confined insulated wall were estimated numerically in a three-dimensional system and were recognized by visualization of a thermosensitive liquid crystal. Local heat transfer is divided into three regions. The first is a two-dimensional forced convection region whose structure is a co-axial circle. The second laminar mixed-convection region begins with the onset of a buoyancy driven flow, which corresponds to thermal plumes rising from the heated impingement surface at discrete circumferential locations. The ascending and descending pair flows form longitudinal streak lines in the mixed convection region. The number of pairs is found to depend on the aspect ratio of circumferential length and distance between nozzle and impingement surface. The third is a three-dimensional natural convection region similar to Benard convection which constructs several cells. The radial Nusselt number distribution averaged along the circumferential direction is also presented corresponding to the flow.