Numerical investigation on vortex structure and jet mixing mechanism in lobed mixer

With computational fluid dynamics software ANSYS CFX,the three-dimensional steady numerical simulation was conducted on the jet mixing flow of lobed mixer to study the formation mechanism and development process of the vortex structure,and its functional mechanism of the forced jet mixing.The results show that based on the SST(shear stress transport) model,the closed N-S equation can simulate the jet mixing process in lobed mixer excellently.While the streamwise vortices induced by the special geometry of lobed mixer depend on an indirect way of twisting the interface between core and bypass flow to accelerate the jet mixing process,normal vortices formed on the promotion of K-H(Kelvin-Helmholtz) instability accelerate the jet mixing directly.The passage vortices are produced by the interaction between the radical inward secondary flow and the low momentum fluid along the wall moving toward the lobe's crest where the passage vortices have an obvious promoting effect on jet mixing.Under the radical pressure gradient within the lobed mixer,boundary layer cut by lobe's leading edge rolls up along the surface of the lobe and forms the horseshoe vortex,and it has little effect on jet mixing.