Numerical study of air-jet vortex generators in a turbulent boundary layer

Abstract

The air-jet vortex generator has been proposed as a credible alternative to the more conventional vane vortex generator. Numerical models of the flow in the neighbourhood of these devices have been constructed to evaluate their potential benefits. The objective of this paper is to consider the sensitivity of a numerical model of a single air-jet vortex generator to the way in which the jet is modelled. The flows were assumed fully turbulent and were solved using the finite volume, Navier–Stokes Code CFX 4 (CFDS, AEA Technology, Harwell) on a non-orthogonal, body-fitted, grid using the k– ε turbulence model and standard wall functions. Streamwise and cross-stream velocity profiles are presented to describe the vortex strength and position. Predicted results were also compared with experimental data. A reasonably good match was observed between the predicted and the experimental streamwise velocity data. However, the magnitudes of the predicted cross flow velocity components were rather weak compared to those of the experiments. The results indicate that the downstream behaviour of the predicted vortex is largely unaffected by the shape of the velocity profile of the incoming jet.