Detailed heat transfer measurements of impinging jet arrays issued from grooved surfaces

Heat transfer augmentation of impinging jet-array with very small separation distances (S/D _j < 1) is attempted by using the grooved orifice plate through which the nozzles with different diameters are fitted. The combined effects of groove and nozzle-size distribution in an array have demonstrated considerable influences on heat transfers via their impacts on inter-jet reactions. With a specified coolant flow rate; the detailed heat transfer distributions over the impinging surfaces of three tested arrays are compared to reveal the optimal selections of separation distance and array configuration. Heat transfer modifications caused by varying jet Reynolds number (Re) and separation distance (S/D _j) over the ranges of 1000 ≤ Re ≤ 4000 and 0.1 ≤ S/D _j ≤ 8 are examined for each test array. In conformity with the experimentally revealed heat transfer physics, a regression-type analysis is performed to develop the correlations of spatially-averaged Nusselt numbers, which permit the individual and interactive effect of Re and S/D _j to be evaluated.