Computations of near field aerodynamics of swirling expanding flows

Abstract

Finite difference computations were carried out in relation to isothermal expanding swirling flows in burner quarls (tiles). The turbulence was modelled both by a second order closure with the Reynolds stress tensor components being computed from their partial differential transport equations and the k −∈ model of isotropic turbulence. Two cases of vortex expansion which were measured at the IFRF were computed and analysed in detail. These cases vere chosen in order to represent different transitions in swirling flow streams which were originally in solid body rotation. Direct comparison of measured and computed flow patterns led to the conclusion that in the analysed cases the Reynolds stress model was far superior to the widely used k −∈ model. However, some further improvements of the Reynolds stress model are still required since, for example, although the position of the internal recirculation zone formed downstream of the burner quarl was predicted very well, the amount of reverse flow was underestimated in one of the analysed cases.