Interaction between lateral jet and hypersonic rarefied flow

Reaction control systems (RCS) are commonly utilized in a variety of air vehicles, and they give rise to complex flow phenomena. For flows dominated by shock waves and expansion, such as lateral jets, a significant gradient is formed in the local region of the flow field, resulting in a high local Knudsen number, and the continuum hypothesis is no longer applicable, even if the freestream belongs to near-continuum flow. As a result, multi-scale simulation approaches should be used to capture the interactions between these multi-scale structures and appropriately determine aerodynamic forces. Our earlier work, which used the conserved discrete unified gas kinetic scheme (CDUGKS) for monatomic gas, studied the flow field features of lateral jets and aerodynamic forces on blunt bodies under various rarefied freestream conditions. In this research, the Rykov model is used to expand the CDUGKS suit for diatomic gas flow while taking into account the excitation of molecular rotational energy. The impact on the flow field and aerodynamic forces from four parameters, namely freestream Mach number, jet Mach number, jet pressure ratio, and nozzle position, is thoroughly investigated. The results show that even if the incoming Mach number is different, the flow field structure and aerodynamic properties don't change much when the jet momentum ratio stays the same. The solid wall stagnation point value and local peak also show some linear relationships. The jet pressure ratio mainly affects the expansion characteristics of the jet, such as the influence range on the solid wall. In addition, with an increase in the distance between the nozzle position and the torque reference point, higher control efficiency can be obtained. The study of these aspects will help us comprehend lateral jet flow and provide reference for the design of an air vehicle's RCS.