Numerical study on the turbulent structure of transverse jet into supersonic flow

The three-dimensional turbulent structure and mixing state of a transverse air jet injected into a Mach 1.9 supersonic crossflow were investigated using a large-eddy simulation. Both a grid sensitivity study and detailed comparisons with acetone planar laser-induced fluorescence data were conducted. The large-eddy simulation results well reproduced both the distribution of averaged injectant concentration and the large-scale turbulent features in the windward region of the jet plume. Large-scale vortices on the windward side of the jet plume caused large protrusions of injectant and were the main cause of the turbulent diffusion of injectant toward the crossflow in the near field. The windward large-scale vortex structure consisted of a string of hairpinlike vortices meandering along the jet trajectory. The head of these hairpin vortices tilted toward the upstream and upward directions. The instantaneous combustible injectant mass flux was evaluated by assuming the injectant air to be ethylene. A large amount of combustible injectant existed inside the large-scale protrusions induced by the windward large-scale vortex structure. The combustible injectant mass flow rate passing through the cross section had substantial fluctuations over time, mainly due to the intermittent appearance of the windward large-scale vortices.