Effects of Jet Plume on Hypersonic Sonic Boom of Slender Bodies

The jet plume effects on sonic boom for hypersonic slender bodies are studied systematically for the first time by simulating nose cone and nose double-cone geometries. The jet plume effects on hypersonic sonic boom are found to be different from the effects on low-supersonic sonic boom because the significantly smaller leading shock angle makes the shock directly interact with the underexpanded jet plume. When sufficiently underexpanded, the jet-induced shocks and shear layers significantly amplify the peak overpressure by a factor of 2–3 at hypersonic flight conditions. A detailed analysis of the dependence of the jet plume effects on the static-pressure ratio, jet Mach number, and vehicle shape has been performed. The static-pressure ratio and jet Mach number are found to have a significant impact on the jet plume effects. The jet plume effects also show sensitivity to the vehicle shape when the static-pressure ratio is small. To quantify the jet plume effects, a nondimensional parameter, [Formula: see text], representing the fraction of jet plume energy transferred to the sonic boom signature, is proposed and used. Finally, the amplification of peak overpressure by the jet plume is found to increase when the signature is propagated downward.