ABSTRACT

In this study, the impingement of a concave surface by hot water jets is investigated. The jets are subjected to a cross airflow at ambient temperature in order to study the effects of the interactions between both fluids on the jet dynamics and the heat flux at jet stagnation area. Different parameters such as the jet diameter, separation distance between two adjacent jets, Reynolds numbers of the jets and the Reynolds number of the airflow are varied. These studies reveal that imposing airflow in the annular space between the jet orifice and the impacted surface can increase the surface wetted area by 40% and can also enhance the heat transfer coefficient at the jet stagnation area by as much 105%. It was also observed that reducing the jet to air mass flow ratio to values below 0.75 leads to the tilting of the water jets and the widest uniformly heated area among the flow parameters tested can be obtained with a ratio of the distance between the jet orifice and the impacted surface and the jet orifice diameter of 4.5 for a single jet impingement.

摘要

在这项研究中，研究了热水喷射对凹面的撞击。为了研究两种流体之间的相互作用对射流动力学和在射流停滞区域的热通量的影响，在环境温度下使射流经受交叉气流。不同的参数，例如喷嘴直径，两个相邻喷嘴之间的间隔距离，喷嘴的雷诺数和气流的雷诺数，是变化的。这些研究表明，在射流孔和受冲击表面之间的环形空间中施加气流可以使表面润湿面积增加40％，并且还可以使射流停滞区域的热传递系数提高105％。还观察到将射流与空气的质量流量比降低到低于0的值。