Influence of the nozzle inlet configuration on under-expanded swirling jet

Abstract

The present study addresses experimental results to investigate the effect of nozzle inlet configuration on under-expanded swirling jets, which is generated by a convergent nozzle with four tangential inlets at the supply chamber. Several different types of plugs and needles, which can be regarded as a means to measure the nozzle inlet pressure or temperature, are employed to change the nozzle supply chamber. The jet supply pressure at the tangential inlets is varied to obtain the swirling jets ranging from a moderately under-expanded to a strongly under-expanded flow at the exit of nozzle. The under-expanded swirling jet flows are specified by the impact pressure measurements and visualized using the shadowgraph optical method. The results show that the major features of the under-expanded swirling jet are considerably influenced by the detailed configuration of the nozzle inlet chamber.