Simulation of flow in a Kaplan Turbine
Tutor / director / evaluatorCervantes, Michael
Document typeBachelor thesis
Rights accessRestricted access - author's decision
The aim of this thesis is to support the development of a procedure to design hydraulic turbines of reaction type. The thesis focuses on the simulation in Ansys CFX, for afterwards exporting the results to another program, in order to compare these simulation results with the experimental results. All the data required from the turbine geometry, boundary conditions and experimental results were taken from Kaveh Amiri Licentiate’s Thesis. There are two different ways to run the simulation considering how the flow characteristics depend on the time: the flow can be specified as steady state, if it is assumed that the steady conditions have been reached after a long time and are not expected to change, or it can also be specified as transient, if the flow conditions are changing and real time information is needed to describe them. Four simulations have been carried out during the thesis; the first two were carried out in a steady state and the final two in a transient state. The results obtained in the first ones were used as initial values for the second ones. All those simulations were run with double precision with the objective to find more accurate results. Also, in order to get the results faster, the simulations were run setting the run mode to two local parallel partitions. The meshes used to run the simulations where: blade geometry with 80024 number of elements, with clearance in the shroud but not in the hub, and a guide vane with 42020 number of elements. Increasing the number of elements would help to get more exact results, but it would also imply more time to run the simulation and more computer resources needed. Also, a better pitch ratio would increase the accuracy of the results but would imply more computer resources. As closer it is the pitch ratio to one as better. During the simulations, a pitch ratio of 0.3 at the interface between the stator and the rotor was used, as they were done with one guide vane and one rotor blade. For that case, in which there are twenty guide vanes and six rotor blades, a pitch ratio of 0.9 can be easily done by representing three guide vanes and one rotor blade. Last but not least, I would personally like to express my gratitude to my tutor, Michel Cervantes, for his attention, support and continuous motivation. I would also like to thank Kaveh Amiri for his patience answering many doubts which I came up with. And finally, thanks to all of my family for their constant encouragement.
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