Computational modelling of three-dimensional impinging jets with and without cross-flow using second-moment closure

Abstract

Computational solutions are presented for three twin-jet configurations which are dominated by flow features arising from normal impingement on a flat plate and jet-jet interaction. Two cases are incompressible, one is subjected to cross-flow, provoking a ground vortex, and another is transonic. All three flows are closely associated with VSTOL operation very close to the ground at low aircraft speed, in which high-speed wall jets arising from impingement collide to form strong fountains. The solutions have been obtained with a conservative FV strategy combining higher-order discretisation and a pressure-correction algorithm, the latter originally devised for incompressible flow and extended to allow the capture of shocks. Unusually, the study investigates the performance of second-moment (Reynolds-stress-transport) closure for 3D jets; indeed, it appears to be the first including the application of this type of model to transonic 3D impinging jets. Comparisons are presented between computational solutions and experimental data, and these demonstrate, particularly for the incompressible cases for which the experimental database is much more extensive, that second-moment closure returns a superior representation of both jet and fountain behaviour relative to the k-ϵ eddy-viscosity model.