Effect on the drag coefficient of various spiked cylinders during buzz phenomenon subjected to hypersonic flows

Abstract

Pulsation mode of transient flow behavior may occur in a violent manner in case of spiked cylinders depending on the geometry, type of spikes, and free stream conditions. Drastic pressure fluctuations near the face of the afterbody have been observed in most cases of pulsating flow mode and thus resulting in drastic variations in the coefficient of drag of the spiked body. The transient analysis of variations in C d with spike length for various spiked cylinders have been carried out in the current work. The variations in C d during one complete cycle as well as variations in time-averaged value of C d with increase in L/D ratios have been analyzed. These variations have been explained with respect to the localized pressure fluctuations, shift in foreshock-aftershock interaction region, effect of effective shielding, and increasing spike lengths. It was found that aerodisk spiked cylinder had the least time-averaged C d. The C d for various other spiked bodies has also been summarized over a range of feasible spike lengths and an optimum design of the spiked body in terms of the spike shape and L/D has also been suggested.