Experimental and theoretical study of surface cooling using a single microjet

The experimental research of heat transfer due to impingement of a single microjet of water and air has been studied on a specially designed rig. Systematic data on radial wall temperature distribution were collected, which enabled development of empirical correlation for heat transfer coefficient applicable both for air and water flows. Two microjet nozzle diameters were studied, i.e. 180 and 260 ěm. The correlation describing the heat transfer coefficient was later used in validation of a model of a single microjet impinging on a flat plate, developed earlier by the authors. Such analytical model of microjet is of a great value in future analysis as it enables to carry out for example sensitivity tests or to appropriately select operational parameters. The presented model is quite general and its further modifications are possible when some of the imposed assumptions are relaxed. More experiments on the structure of a single microjet are needed which will confirm the correlation presented in the paper.