Numerical Study of Dual Lateral-Jet Interactions in Reaction Control Systems Under High-Speed Rarefied Flow Conditions

Reaction control systems (RCSs) provide rapid and effective attitude-control capabilities for high-speed vehicles operating in high-altitude, low-density environments, where conventional aerodynamic control surfaces become inefficient. However, interactions between lateral jets and high-speed crossflows generate complex shock, separation, and vortex structures, which may significantly alter RCS control effectiveness. In this study, the nonlinear coupled constitutive relations (NCCR) model is employed to investigate dual lateral jet interactions over a cone–cylinder vehicle at an altitude of 80 km and a freestream Mach number of 10. The effects of the jet pressure ratio on the normal force coefficient, force amplification factor, moment amplification factor, wall pressure distribution, and flowfield structure are systematically analyzed. The results show that the absolute value of the normal force coefficient increases with increasing jet pressure ratios, whereas both the force and moment amplification factors decrease. At high-pressure ratios, the direct jet thrust becomes dominant and the relative contribution of jet-induced surface aerodynamic forces decreases. A second small-scale high-pressure region is observed between the two jet orifices, which is attributed to the expanded region of influence of the horseshoe vortex. In addition, the enhanced wrapping effect at high-pressure ratios adversely affects the aerodynamic contribution to RCS control efficiency. As the jet pressure ratio decreases from 750–1500 to 25–50, the relative deviations between Navier–Stokes- and NCCR-predicted force and moment amplification factors decrease from 0.019% to 0.262% and from 0.015% to 0.228%, indicating more pronounced rarefaction and non-equilibrium effects at low jet pressure ratios.