Numerical simulation of shock-enhanced mixing in nonuniform density turbulent jets

摘要

A numerical study of the interaction of weak normal shock waves with turbulent jets was conducted. The configuration consisted of a planar jet of air, helium, or carbon dioxide situated on the centerline of a shock tube with an air coflow. The shock strengths were M-s = 1.2 and 1.4. The numerical model was based on a time-dependent, Navier-Stokes approach and a two-equation q-omega turbulence model. The results indicate that passage of a shock through low-density (helium) jets produces a vortexlike structure not seen for the case of the air or carbon dioxide jets. Helium jets exhibit a decrease in mean jet fluid concentration due to shock interaction of up to approximately 30 at a location 30 jet exit heights downstream of the jet exit for a shock strength of M-s = 1.4. The amount of mixing enhancement increases with increasing shock strength and decreases with increasing downstream distance. In comparison, the air and carbon dioxide jets show a significantly smaller degree of mixing enhancement. These results are qualitatively consistent with recent experimental results in axisymmetric, turbulent jets subject to normal shock passage. References: 28