A numerical study of the effects of jet-aft wall temperatures on the dynamics of jets in hypersonic crossflows

Abstract

For high-speed vehicles such as scramjets, internal combustion chamber temperatures play an important role in the engine performance, with the influence of the temperature on the fuel injection dynamics being of key interest. In this study, large eddy simulations are employed to investigate a sonic jet in a Mach 5 crossflow with a momentum flux ratio of 5.8 and the parametrization of the temperature of the wall aft of the jet. Both uniform and non-uniform wall temperatures are analyzed, with two jet-to-crossflow temperature ratios of 8.06 and 3.23 investigated. It is found that the wall temperature primarily influences the near wall flow, with a small amount of entrainment into the jet plume via the counter-rotating vortex pair as the low velocity flow is limited by the near-wall shear layer. It is found that the aft-recirculation zone is expanded with the increasing wall temperature, which has the effect of increasing the penetration of the jet plume into the far field. Five recirculation regions are observed ahead of the jet, which are noted to result from the interaction between the crossflow and jet flow for both the adiabatic and temperature-controlled cases, with jet fluid flowing into the forward boundary layer, and thus near-wall mixing is observed. Horseshoe vortex strength is seen to dissipate when passing over the cooled walls, thus reducing the mixing potential near the wall, where the opposite is true for heated walls. Lateral spread of the horseshoe vortices is seen to increase with cooled walls, increasing the near-wall mixing potential.