COMPUTATIONAL MODELING OF 3-DIMENSIONAL IMPINGING JETS WITH AND WITHOUT CROSS-FLOW USING 2ND-MOMENT CLOSURE

Computational solutions are presented for three twin-jet configuration s 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 anoth er is transonic. All three flows are closely associated with VSTOL ope ration very close to the ground at low aircraft speed, in which high-s peed wall jets arising from impingement collide to form strong fountai ns. The solutions have been obtained with a conservative FV strategy c ombining higher-order discretisation and a pressure-correction algorit hm, 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 t hese demonstrate, particularly for the incompressible cases for which the experimental database is much more extensive, that second-moment c losure returns a superior representation of both jet and fountain beha viour relative to the k-epsilon eddy-viscosity model.