Three-Dimensional Heat Transfer of a Confined Circular Impinging Jet With Buoyancy Effects

This paper describes the heat transfer and flow characteristics of a single circular laminar impinging jet including buoyancy force in a comparatively narrow space with a confined wall. Temperature distribution and velocity vectors in the space were obtained numerically by solving three-dimensional governing equations for the Reynolds number $Re=umD/ν=400-2000$ and the dimensionless space, $H=h/D=0.25-1.0.$ After impingement, heat transfer behavior on the impingement surface is divided into a forced convection region, a mixed convection region, and a natural convection region in the radial direction. The local heat flux corresponding to these three regions was visualized using a thermosensitive liquid crystal. Moreover, with the increase in Reynolds number, Re, and dimensionless space, H, the recirculation flow on the impingement surface moves downstream and its volume increases correspondingly. The Nusselt number averaged from r=0 to the minimum point of peripherally averaged Nusselt number, Num, was evaluated as a function of Re and H.