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exit-velocity
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A general methodology for bearing design in non-symmetric T-shaped sections in extrusion process
, Article Journal of Materials Processing Technology ; Volume 212, Issue 1 , 2012 , Pages 249-261 ; 09240136 (ISSN) ; Assempour, A ; Farahani, S ; Sharif University of Technology
Abstract
In this study, a general methodology has been developed to design the proper bearing in order to eliminate the curvature of the final product in extrusion process. Three smooth curved (advanced-surface) dies with non-symmetric T-shaped sections and different off-centricities have been studied. For each die, the proper bearing has been designed and physical and numerical modeling have been performed to validate the design. The design procedure is as follows: A formulation, based on Bezier curves, has been used to determine the exit velocity profile. Since the result of Bezier method is different from the actual velocity profile, the Chitkara corrective function has been modified and applied...
Semi analytical solution to transient start of weakly underexpanded turbulent jet
, Article Journal of Fluids Engineering, Transactions of the ASME ; Volume 133, Issue 9 , Sep , 2011 ; 00982202 (ISSN) ; Saidi, M. H ; Mozafari, A. A ; Sharif University of Technology
2011
Abstract
This study presents a semi analytical solution for the transient weakly underexpanded jet. Different polytropic processes are compared with available experimental data in the literature to assess the best process for steady and transient weakly underexpanded jets. The steady state results agree reasonably well with the experimental and analytical data. It is also shown that isentropic process evaluates steady injection better than other processes. Tip penetration of transient results was compared with available data in literature, and no exact agreement for isothermal and isentropic is observed. This appears due to the linearization of equation of state. It is suggested that more accurate...
Mixed convection cooling of a heated circular cylinder by laminar upward-directed slot jet impingement
, Article Heat and Mass Transfer/Waerme- und Stoffuebertragung ; Volume 46, Issue 2 , 2009 , Pages 225-236 ; 09477411 (ISSN) ; Habibi, K ; Faghani, E ; Ashjaee, M ; Sharif University of Technology
Abstract
An experimental and numerical study has been carried out to investigate the heat transfer characteristics of a horizontal circular cylinder exposed to a slot jet impingement of air. A square-edged nozzle is mounted parallel with the cylinder axis and jet flow impinges on the bottom of the cylinder. The study is focused on low Reynolds numbers ranging from 120 to 1,210, Grashof numbers up to Gr = 10Re2 and slot-to-cylinder spacing from 2 to 8 of the slot width. The flow field is greatly influenced by the slot exit velocity and the buoyancy force due to density change. A Mach-Zehnder Interferometer is used for measurement of local Nusselt number around the cylinder at 10° interval. It is...