| A numerical study, using the Direct Simulation Monte Carlo (DSMC) approach, of the interaction effects between two identical sonic under-expanded nitrogen jets under rarefied conditions is reported. In this study, the effects of the jet stagnation Knudsen number (Kns), the ratio of the stagnation-to-background pressure (Ps/P b), and the distance between the jet orifices (L/D ) were investigated for a range of these parameters. The "primary-secondary" shock-cells structure has been successfully reproduced when flow is in the near continuum flow regime. The response of the system to various combinations of Kns, Ps/Pb, and L/D, is reported with a focus on the shock structures as well as the rarefaction effects. It shows that the background pressure has a very significant effect on the physics of flow, and the interactions between the two jets affect the location of the Mach disks for both the primary and secondary jets. When flow is rarefied, a study of the rotational-translational non-equilibrium showed large deviations between the translational and rotational temperatures in the vicinity of the orifice plate. It is also found that the background gas helps to reduce the translational-rotational non-equilibrium effects in the secondary jet. |
