LES of high speed jet flow from convergent-divergent rectangular S-bend ducts using synthetic inlet conditions

The effect of upstream duct curvature on the exhaust plume of a jet engine is further studied. Using synthetically created turbulence, improvements are made to the flow through out the S-bend validation case previously studied. The effect of a contracting 70° S-bend duct on the over-expanded exhaust plume emanating from a rectangular nozzle of aspect ratio 5.8:1 at a nozzle pressure ratio of 2.5 and Reynolds number of 7.61×105 is then studied. A modified version of the synthetic eddy method for creating artificial turbulence is initially validated. The validation of the Hydra CFD code is then expanded upon for an S-bend duct including both RANS and LES methodologies. For the combined S-bend and nozzle cases the total pressure gradients that were previously observed at the nozzle exit plane for k-ε RANS are also similarly observed using LES with synthetically created in flow turbulence thus confirming the existence of such features. The calculations were carried out using an unstructured, median-dual CFD solver with predominantly hexahedral elements containing approximately 175 million nodes.