Abstract. Numerical investigations of hydraulic turbo machines under steady-state conditions are state of the art in current product development processes. Nevertheless allow increasing computational resources refined discretization methods, more sophisticated turbulence models and therefore better predictions of results as well as the quantification of existing uncertainties. Single stage investigations are done using in-house tools for meshing and set-up procedure. Beside different model domains and a mesh study to reduce mesh dependencies, the variation of several eddy viscosity and Reynolds stress turbulence models are investigated. All obtained results are compared with available model test data. In addition to global values, measured magnitudes in the vaneless space, at runner blade and draft tube positions in term of pressure and velocity are considered. From there it is possible to estimate the influence and relevance of various model domains depending on different operating points and numerical variations. Good agreement can be found for pressure and velocity measurements with all model configurations and, except the BSL-RSM model, all turbulence models. At part load, deviations in hydraulic efficiency are at a large magnitude, whereas at best efficiency and high load operating point efficiencies are close to the measurement. A consideration of the runner side gap geometry as well as a refined mesh is able to improve the results either in relation to hydraulic efficiency or velocity distribution with the drawbacks of less stable numerics and increasing computational time.
IntroductionThe increasing availability of computer resources allow the use of more accurate numerical schemes such as advanced turbulence models or higher discretization of the model domain. Therefore the Norwegian University of Science and Technology and Lulea University of Technology jointly are organizing a set of workshops to determine the state of the art of high head Francis turbine simulation. As the first of three upcoming workshops the present one is aimed at steady state simulations of a model turbine in three different operating points. In the pending workshops more sophisticated investigations like transient operating conditions and fluid structure interactions are investigated.Voith Hydro, as one of the world's leading manufactures in the field of hydropower equipment and services, gathered a broad experience in hydraulic model test and numerical simulations. Increasing demands of computational fluid dynamics (CFD) to support the hydraulic development process lead to a continuous improvement of computer resources and simulation methods. To validate the current development process the provided geometry is used as an input for the in-house mesh and setup procedure. The numerical results are validated with experimental data and can also be compared with the results of other participants.
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