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Design comparison for piston rod solution
2009 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The ever increasing energy consumptions and growing environmental awareness requires a steady development of hydro power efficiency. This development puts hard demands on the internal components of a Kaplan runner. Therefore is this design comparison performed to find differences between an old design solution and a new solution untested for larger runners. The work has been performed at Andritz Waplans located in Vaplan. In the design comparison four design aspects have been evaluated: structural properties, assemblage, manufacturing and procurement. Focus has been on the structural calculations where the new designs fatigue properties have been evaluated, since this was where the most benefits were thought to be. The comparisons have been made by comparing two design solutions with the same premises. It was done by choosing an existing example of the old design and adapting the new design to its size and other prerequisites. The chosen existing example was from Näsaforsens hydro plant. The fatigue calculations that have been performed are according to the FKM guideline. The basis for the calculations are the use of FEM simulations and a load case composed by a service load measurement that is scaled to fit Näsaforsen and to give 40 years of service. The whole calculation procedures are described in detail. The other aspects of this comparison have been evaluated by interviews with experts within each field. During these interviews were chosen evaluation points used to find differences between the two designs. The depths of those evaluations are more shallow than the structural evaluation. It has been found that the two designs have practically the same fatigue properties and it is possible for the new design to fulfill other structural criterions as well, such as nominal stress and buckling. It has also been found that when making a specific case comparison between the two designs for Näsaforsens premises it is possible to reduce the total costs, due to the large difference in material cost when comparing a wrought bar to an ordinary round bar. In the comparison it has also been seen that the new design might take longer time to assemble due to control measurements and possible position adjustments. It was also established though that it is possible to assemble the new design without any drastic changes of assemblage routines. In the comparison the two designs are only compared for the premises of Näsaforsen. The results are only valid under those conditions. Further delimitations are that no structural analysis calculations have been performed on the runner hub.

Place, publisher, year, edition, pages
Keyword [en]
Keyword [sv]
URN: urn:nbn:se:ltu:diva-45858ISRN: LTU-EX--09/158--SELocal ID: 384528d0-1863-469c-80a6-472151d42aceOAI: diva2:1019156
Subject / course
Student thesis, at least 30 credits
Educational program
Mechanical Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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