7,679 research outputs found
Efficient computation of spinning modal radiation through an engine bypass duct
No full textThe aim of this work is to accurately and efficiently predict sound radiation out of a duct with flow. The sound
propagation inside a generic engine bypass duct, refractions by the shear layer of the exhaust flow, and propagation
in the near field are the main focus of the study. The prediction uses either a modified form of linearized Euler
equations or an alternative model based on acoustic perturbation equations, which were extended to cylindrical
coordinates. The two models were compared on a canonical case of sound propagation out of a semi-infinite duct with
flow. Good agreements between the predictions were achieved. The more general case of a generic aircraft engine
bypass duct with flow was then investigated with the technique of adaptive mesh refinement to increase the
computational efficiency. The results show that both linearized Euler equations and acoustic perturbation equations
models can predict the near-field sound propagation and far-field directivity. The acoustic perturbation equations
model, however, is more adaptive for its suitability to an arbitrary background mean flow
Composition Control of r.f.-Sputtered Ti50Ni40Cu10 Thin Films Using Optical Emission Spectroscopy
No full textSurface analyses and biocompatibility study of 500 °C oxidized Ni50Ti50 and Ni40Ti50Cu10 shape memory alloys
No full textComparison of landmark identification in traditional versus computer-aided digital cephalometry
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The effects of differences in landmark identification upon the cephalometric measurements in traditional versus digitized cephalometry
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