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Lägg inte ut - Design and analysis of aggressive intermediate ducts
2003 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The two objectives of this thesis were to validate different turbulence models for CFD calculations on intermediate transition ducts and to develop a design system for creating, modifying and evaluating different duct designs. The numerical investigation of turbulence modeling was performed using the commercial code Fluent. Four turbulence models were evaluated. Three two- equation models: realizable k-e, Wilcox k-w and SST k-w and one Reynolds stress model (RSM). Two different near-wall treatments were also investigated: non-equilibrium wall functions and a low-Re number model. For high accuracy modeling of the boundary layer development and near-wall stresses RSM with a low-Re number near-wall approach proved to be superior to the other models. The velocity and pressure distributions did not vary considerably comparing all four turbulence models or comparing the two near- wall treatments. The user interface of the design system was created using the mathematical computing language Matlab and the duct geometries are represented by NURBS curves, handled using the C library Nlib. The features of the design system include: • 2-dimensional duct generation based on a hub and a shroud contour shape or on a mean line and an area distribution • An inviscid, axi-symmetric flow solver • Thwaites’ laminar separation criteria • Stratford’s turbulent separation criteria • Truckenbrodt’s turbulent boundary layer approximation and separation criteria

Place, publisher, year, edition, pages
Keyword [en]
Technology, transition duct, IMC, intermediate case, TCF, turbine center, frame, realizable k-e, k-w, SST, RSM, Fluent, duct design, NURBS, Nlib, Matlab, separation, Stratford, Thwaites, Truckenbrodt
Keyword [sv]
URN: urn:nbn:se:ltu:diva-51966ISRN: LTU-EX--03/326--SELocal ID: 9210cab0-d5b0-4efd-89b4-e123b29d45aeOAI: diva2:1025332
Subject / course
Student thesis, at least 30 credits
Educational program
Engineering Physics, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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