Influence of nozzle geometry on underexpanded axisymmetric free jet characteristics

The effect of nozzle geometry on the structure of a supersonic free jet is investigated both experimentally and numerically for three simple nozzle geometries. In the experiments, the relation between the Mach disk height and diameter and the nozzle pressure ratio are investigated using the schlieren method. In contrast to results obtained in previous studies, our experimental results show that the Mach disk height changes depending on the nozzle geometry. Numerical investigations were conducted by introducing flows upstream of the nozzle and the influence of these upstream flows on free jet configuration has been discussed.