Numerical investigation of the round jet in crossflow at high velocity ratios with special emphasis on the evolution of vortex structures

Abstract

We investigate the evolution and interaction mechanism of different vortex structures for the jet in crossflow by a high precision numerical method. To verify the accuracy of the numerical method, the numerical and experimental results are compared. Numerical results show a reasonable agreement with the experimental data. The typical vortex structures can be clearly identified in the flow field, including shear layer vortices, horseshoe vortices, counter rotating vortices pairs, and wake vortices. Through the analysis of spatial distribution of different vortex structures, the formation and interaction mechanisms of different vortices are discussed in detail. The results show that the shear layer rolling up appears due to the strong rotation, inducing the formation of the shear layer vortices. The influences of velocity ratios on the vortex structures are further investigated. At low velocity ratios, the rotation is weak along the windward of the jet. With the increase in the velocity ratios, the stronger rotation is formed near the jet exit hole, inducing the instability of interface and formation of the shear layer vortices to occur earlier. In the far flow field, as the shear layer vortices gradually break up into the fine-scale vortices, both the rotation and shear tend to become weaker at different velocity ratios.