Movement of Impingement Heat Transfer by a Single Circular Jet with a Confined Wall.

Impingement heat transfer and flow along the radial and circumferential direction by a single circular laminar jet with a confined insulated wall were estimated numerically in three-dimensional form and were recognized by visualization of a thermosensitive liquid crystal. Local heat transfer is divided into three regions. The first is two dimensional forced convection region whose structure is coaxial circle. The second laminar mixed-convection region begins with onset of the buoyancy-driven flow, which corresponds to thermal plumes rising from the heated impingement wall at discrete circumferential locations. The ascending and descending pair fluid forms respectively 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 local value of Gr/Re2 on the onset of the buoyancy driven flow is from 80 to 100. The third is like Benard convection which constructs several cells. The radial Nusselt number distribution averaged along the circumferential direction is also presented corresponding to flow.