Effect of the injector geometry on a sonic jet into a supersonic crossflow

Abstract

Large-eddy simulation of a sonic injection from circular and elliptic injectors into a supersonic crossflow has been performed. The effects of injector geometry on various fundamental mechanisms dictating the intricate flow phenomena including shock/jet interaction, jet shear layer vortices and their evolution, jet penetration properties and the relevant turbulence behaviors have been studied systematically. As a jet issuing transversely into a supersonic crossflow, salient three-dimensional shock and vortical structures, such as bow, separation and barrel shocks, Mach disk, horseshoe vortex, jet shear layer vortices and vortex pairs, are induced. The shock structures exhibit considerable deformations in the circular injection, while their fluctuation becomes smaller in the elliptic injection. The jet shear layer vortices are generated at the jet periphery and their evolution characteristics are analyzed through tracing the centroid of these coherent structures. It is found that the jet from the elliptic injector spreads rapidly in the spanwise direction but suffers a reduction in the transverse penetration compared to the circular injection case. The turbulent fluctuations are amplified because of the jet/crossflow interaction. The vertical Reynolds normal stress is enhanced in the downstream of the jet because of the upwash velocity induced by the counter-rotating vortex pair.

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