Flow fields around spanwise-inclined elliptical jets in supersonic crossflow

Abstract

Motivated by favorable effects in separation control with air-jet vortex generators in aerospace applications, we performed implicit large-eddy simulations to analyze the flow physics of spanwise-inclined elliptical jets in supersonic crossflow and reveal the influence of aspect ratio. Orifices with similar hydraulic diameters and aspect ratios of 0.5, 1.0, and 2.0 were studied at Mach number M=2.5 and momentum-thickness Reynolds number Reθ=7000. The jet injection results in the formation of asymmetric flow features (bow and barrel shocks, upstream and downstream separation regions, and vortical structures), which are qualitatively similar for all cases. Compared with the more commonly-studied wall-normal injection, the axis-switching phenomenon and its effects are very mild for spanwise-inclined injection. For the low-aspect-ratio orifice, the clockwise-rotating major vortex strengthens and vice versa for the high-aspect-ratio orifice. Flow penetration increases with aspect ratio; however, the influence of the injection is limited within the boundary layer and the outer layer is undisturbed. In the far field, the enhanced momentum transfer makes the boundary layer more resistant to separation for all orifices. Combined with the amplified vorticity for elliptical cases, elliptical jet orifices become more effective for separation control purposes than circular orifices.