Large eddy simulation of transverse single/double jet in supersonic crossflow

In this paper, large eddy simulation of transverse sonic single/double hydrogen jets into supersonic Mach 2 crossflow have been carried out to investigate the complex flow structures and the mixing performance. Detailed turbulence characteristics, in terms of the instantaneous and mean flow fields, the vortex structures and their evolutions, the turbulence kinetic energy and the Reynolds shear stress distributions, the maximum hydrogen mass fraction and jet penetration, have been provided. Results of the two-dimensional and three-dimensional streamlines illustrate that the trailing counter-rotating vortex pairs (TCVP), the secondary TCVP of primary jet and the horseshoe vortex can merge and form a new horseshoe vortex. Three counter-rotating vortex pairs (CVP) are formed in the downstream of secondary jet: the CVP-B due to interactions between the supersonic crossflow and secondary jet; the CVP-C due to interactions between the supersonic crossflow, primary and secondary jets; and the CVP-D due to interactions of the supersonic crossflow and primary jet. The presence of primary jet flow alters the Reynolds shear stress distributions after the secondary injection with the influence of these large-scale structures. In addition, the two-stage jet injection system is proved to yield a better mixing performance than the single jet system.