Large Eddy Simulation of Transverse Jets into Crossflow with Mixing-Enhancement Wells

Transverse jets into crossflows (JICF) have wide applications in natural sciences and engineering. The present work proposed the use of a mixing well to enhance the mixing of a gaseous jet into crossflow. A compressible-flow Navier-Stokes solver is applied to examine flow structures and mixing efficiency by using a large-eddy-simulation technique and dynamic stress and scalar flux models, Two different well configurations and two jet-to-crossflow velocity ratios, 2 and 4, are considered at a jet velocity of 160 m/s. The jet trajectory, counter-rotating vortex pair (CVP), and near-field vortical structures are discussed. Scalar mixing efficiency is quantified by the maximum concentration decay and the spatial mixing deficiency (SMD) along the crossflow direction. Results show that in the presence of a mixing well, the strengths of horseshoe, shear layer, and wake vortices, and CVP instability and asymmetry are enhanced noticeably. Furthermore, SMD results show the nearfield scalar mixing rate is significantly strengthened by intensified vortex motions. The jet trajectory and penetration is affected by the mixing well. Such effect is sensitive to the velocity ratio. An optimization scheme can be applied to search for the optimal mixing well configuration for mixing control.