Experimental Study of the Effect of a Cross Airflow on the Dynamics and Heat Transfer Performance of Impinging Circular Water Jets on a Concave Surface

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.