Studies of low-density freejets and their impingement effects

A detailed experimental investigation of freejets and their impinging flowfields has been carried out. Studies were conducted for different pressure ratios, and the influence of Reynolds number on flow freezing was examined, A conical convergent-divergent nozzle of large area ratio, typically employed in aerospace applications, was used in the studies, Quantitative data of freejet and impingement flowfields, which could be used as a benchmark for checking the results obtained from numerical simulations such as the direct simulation Monte Carlo method, are presented. Forces due to plume impingement on an adjacent surface were estimated, The impingement effects were found to be considerable at high Reynolds numbers, whereas flowfield properties were found to be unaffected due to the presence of the plate at low Reynolds numbers. The freejet and the impinging flowfield were visualized using a glow discharge technique. The features of transition flow were observed in low Reynolds number flows. The flowfield modifications brought about by the influence of the flat plate could also be visualized.