Experimental study of swirling flows and mixing in non-axisymmetric/2-D nozzle
The proliferation of shoulder fired surface-to-air missiles has increased the concern of the Infra-Red(IR) missile threat in the aerospace industry. There are many ways to mitigate the infra-red missile threat; lowering the IR signature of the jet exhaust is one method that is of interest to the military and the aerospace industry. This thesis investigates the effects of swirling flows on the jet exhaust plume mixing of a 2-D transitional nozzle. Tang investigated a 2-D nozzle that has performed with increased efficiency and better mixing with a 20 degree swirler. The type of flow field that is used in this thesis to investigate the effects of mixing is a dual swirl flow field where the swirl is counter rotating. The 2-D nozzle was tested with a 10 degree, 20 degree and 30 degree dual swirler and it was also tested without any swirlers. The 2-D nozzle and dual swirlers were tested on the Bi-Annular Nozzle Rig(BANR). The BANR was designed and built to test and study airbreathing propulsion nozzles at hot-firing conditions. It is also equipped with a thrust measurement system, a plume rake that surveys plume temperatures and pressures and other instrumentation devices to record relevant data. The nozzle and the swirlers were tested for their thrust performance and for plume surveys. The thrust analyses were conducted from NPR of 1.6 to 3 at a temperature of 800F. The plume surveys were conducted at a NPR of 1.6 and a temperature of 800F. The results from the experiments showed that these dual swirlers greatly enhanced the rate of dissipation in the plume. The counter-rotating vortices have successfully managed to entrain large amounts of ambient air to induce mixing. The 30 Degree dual swirler performed best in terms of dissipation. As expected, the higher the angle of the swirler, a greater dissipation was observed in the plume. The thrust efficiency however decreased as the angle of attack of the swirlers increased. There was a well defined trade-off between the degree of plume mixing and the thrust efficiency of the nozzle and the swirlers.
Heister, Purdue University.
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