Numerical simulation of large-scale structures in exhaust jet/wake vortex merging

Abstract

This paper reports on a 3D temporal numerical simulation of the interaction between a jet flow and a trailing vortex. The simulation was performed from an experimental database of the vortex wake generated by a rectangular wing NACA0012 equipped with two jets beneath the airfoil. In this work, we focus on the 3D vorticity and scalar (initially included in the jet) fields in the vortex wake. The turbulence induced by the jet flow held interacts with the vortex, resulting in the large-scale structure generation outside the vortex core whereas the region very close to the core keeps its laminar state. The scalar field is subject to distortion and stretching inside the azimuthal vorticity tubes. The scalar concentration provides a reliable signature of where the helical instability occurs outside the vortex core. Later, the counter rotating vortices undergo a connection and consequently lose coherence in a very short time. The resulting scalar field concentrates then in small-scale eddies.