Jets in a crossflow including the effects of dual arrangements, angle, shape, swirl and high turbulence

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1986
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Virginia Polytechnic Institute and State University
Abstract

In this experimental research, jets injected from a flat plate into a crossflow at large angles have been studied. Results were obtained as surface pressure distributions and mean velocity vector plots and turbulence intensities and Reynolds stresses in the jet plume. Rectangular jets (length/width=4) and circular jets were tested. The rectangular jets were aligned streamwise as single and side-by-side dual jets. For the rectangular jets, the jet injection angles were 90° and 60°. The circular jet results were obtained for a single circular jet injected at a 90° angle. Different types of the circular jets were studied with low exit turbulence, high exit turbulence, 40 % swirl and 58 % swirl. The surface pressure distribution results were obtained for jet to freestream velocity ratios of 2.2, 4 and 8 for most of the cases mentioned. Mean velocity vector plots were obtained for the 90° and 60° side-by-side dual rectangular jets and all the circular jet types, mainly for the jet to freestream velocity ratio of 4. Turbulence results were obtained for a jet to freestream velocity ratio of 4 for the 90° and 60° side-by-side dual rectangular jets and for the circular jet with low exit turbulence cases. The results showed that the higher exit turbulence reduced the penetration height, and it also reduced the surface area influenced by the negative pressures. The swirl caused asymmetric pressure distributions, and the swirl effects were more pronounced for lower velocity ratios. The rectangular jets featured strong negative pressure peaks near the front nozzle corners. The 60° rectangular jets produced lower magnitude negative pressures which are distributed over a lesser area when compared to the 90° rectangular jets.

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