Heat transfer at the stagnation point of a free-falling impinging liquid jet

The results of an analytical study of unsteady heat transfer in the vicinity of a stagnation point of an axisymmetric impinging liquid jet are presented. A self-similar solution is obtained, which allows the analysis of heat transfer behavior as a function of the Reynolds number, distance from the nozzle to the surface, and characteristic time. The behavior of the Nusselt number for the solution in asymptotically limiting cases is shown: the Froude number Fr ≫ 1 (small distances from the nozzle to the barrier) and Fr ≪ 1 (large distances). It is noted that the effect of the Froude number can be quite significant and should be taken into account when predicting heat transfer. Significant intensification of heat transfer is shown for a pulsed impinging jet at short pulse durations.