Numerical Study of Novel Drag Reduction Techniques for Hypersonic Blunt Bodies

Numerical simulations of a full three-dimensional hemispherical body in hypersonic flow are conducted and innovative techniques involving forward injection of gas from the stagnation point of the sphere are investigated; techniques include annular (ring) and swirled injection both with and without upstream energy deposition. Objectives of the analysis are the assessment of 1) drag reductions achieved on the blunt body (including the detrimental drag effect caused by the forward-facing injection itself) and 2) stability characteristics of the jet. Studies are conducted at freestream Mach numbers of 10 and 6.5 at standard atmospheric conditions corresponding to 30 km altitude. While centered forward injection without upstream energy deposition is confirmed to be highly unstable either with or without swirl, annular ring injection exhibits a stabilizing influence on the jet. Energy deposition upstream of the body is shown to significantly enhance stability and penetration of the forward injection jet for all techniques.