The effect of upstream duct curvature on the exhaust plume of a jet engine is currently undocumented. Here, three different upstream curvatures are simulated using CFD to investigate the effect of upstream duct curvature 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 × 10 5 . Due to the lack of available experimental data for curved ducts connected to high speed jets, the initial work was to validate the methodology for separate S-bend and rectangular nozzle high speed jet cases. These showed that RANS methods were poor for predicting secondary flows in the S-bend and for predicting mixing and potential core length in the rectangular jet. However, LES did show significant improvements for the rectangular jet and correctly predicts the shear layer mixing. Calculations were carried out using an unstructured, median-dual CFD solver with predominantly hexahedral elements containing approximately 65.5−67.5 million nodes. For the combined S-bend and nozzle cases it was seen that increasing upstream duct curvature reduces the potential core length and increases losses in the upstream duct. Transverse total pressure gradients were also observed at the nozzle exit plane in both k-ǫ and WALE LES turbulence models, however to a significantly smaller degree in the latter. The upstream duct curvature was also seen to have an impact on the shock cell development, altering both number and location.
Composite laminates are in widespread use in the aerospace industry. As well as sa tisfying strength and stiffness criteria, the final laminate design has to be manufacturable in terms of compatibility between adjacent panels, thus introducing conflicting constraints on the allowed laminate stacking sequences. An attempt to automate the laminate design process is described. The method uses a mixture of a genetic algorithm and heuristics to satisfy the various design and manufacturing constraints. Multiple zones are allowed, where each zone defines a panel together with a set of applied loads. Guide laminates and a blending methodology allow each zone to share common plies. This creates ply continuity across the structure and avoids the scenario seen in other laminate optimisation tools where each optimised zone contains unrelated laminates which are not practical from a manufacturing perspective.
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