A Study on the Heat Transfer Characteristics on Flat Plate Surface by Two-dimensional Impinging Air Jet

평판전열면(平板傳熱面)에 충돌(衝突)하는 2차원충돌분류계(二次元衝突噴流系)의 열전달특성(熱傳達特性)에 관(關)한 연구(硏究)

The purpose of this study is to investigate the heat transfer characteristics and the flow structure in the case of rectangular air jet impinging vertically on the flat heating surface. The maximum value of Nusselt number at stagnation point is observed at H/B=10. It is found that this trend has been caused by the effect of stretching of large scale vortex in the stagnation region. For potential core region the Nusselt number distribution in the downstream of the stagnation point decreases gradually and begins to increase at about X/B=3. From the flow visualization it could be seen that small eddy produced from the nozzle edge grows in large scale and that large scale eddy disturbed the thermal boundary layer on the heating plate. The local average Nusselt number becomes maximum at X/B=0.5 regardless of H/B variation.