CFD modelling of ski-jump spillway in Stornnforsen

University essay from KTH/Marina system

Author: Simon Eklund; [2017]

Keywords: ;

Abstract: Traditionally when designing dams and spillways, experiments in physical scale models are conductedin order to determine whether or not the design fulls it purpose, and to identify and avoid undesiredproblems, such as unfavourable ow patterns and unwanted water splatter. Physical models can oftenbe expensive and time consuming to build, and often suer from scale eects that in uence the results.Uniper and Vattenfall have recently done experiments in a physical 1:50 scale model of the dam Stornnforsen,in order to test new solutions for the energy dissipation from the spillways. One of the testedsolutions is a ip bucket at the bottom of the right surface spillway.In this project the same solution is numerically modelled, using the CFD software ANSYS® Fluent®,and the results are compared to those from the experiments. The CFD simulations are done both in fullscale and model scale, in order to identify potential scale eects. The aspects that are compared are theheight and length of the jet from the ip bucket.In addition to the CFD simulations, the height and length are also calculated semi-empirically, usingtwo dierent methods.Altogether the results correspond quite well to the experimental values. Some possible scale eects areobserved, where the jet from the full scale simulation is more dispersed than the jet from the model scalesimulation. The jet trajectory from the full scale simulation is also a bit lower than the jet from theexperiments and model scale simulations.The grid independence for the simulations is not quite satisfactory, and the grid should be rened to getmore reliable results. Due to lack of time and computational power any further grid renement is notdone in this project.

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