Aerodynamic Effects of Surface Protuberance Size on Slender-Bodied Supersonic Vehicle

The presence of protuberances can create an asymmetric flowfield, which contributes to side forces in slender-bodied launch vehicles. In this study, we conduct numerical calculations using a supercomputer at Japan Aerospace Exploration Agency (JAXA) on a slender body with a different-sized protuberance at Mach 1.5 to systematically determine the aerodynamic effects of the protuberance size. The protuberance size is varied in its height and width. According to the results, it is demonstrated that the side force significantly increases when the height of the protuberance increases. This is because, the higher the protuberance, the farther the wake vortex produced by the protuberance moved away from the body. Consequently, the flow asymmetry between the protuberance side and clean side is augmented, and the side force increases. In contrast, the side force is almost constant when only the width of the protuberance is changed. The results of this study indicate that when attaching the protuberance to the vehicles the height of the protuberance should be lowered, and the width of the protuberance should be increased to secure the volume of the protuberance and reduce the increase in side force.