The Norwegian University of Science and Technology (NTNU), Norway, and Luleå University of Technology (LTU), Sweden, announced three workshops for Francis turbines. The goal of the first one was to determine the state-of-the-art of numerical predictions for steady operating conditions. The second and the third workshop will be focused on transient operation of turbines and fluid-structure interaction, respectively. In all workshops, a high-head Francis turbine model (Tokke model) will be employed as a reference test case. The model was designed and experimentally measured at Water Power Laboratory at NTNU.
Aljaž Škerlavaj and Mitja Morgut attended Workshop FRANCIS-99 in Trondheim, Norway. ACCUSIM group participated with the paper:
Numerical simulation of flow in a high head Francis turbine with prediction of efficiency, rotor stator interaction and vortex structures in the draft tube
Authors: D Jošt, A Škerlavaj, M Morgut, P Mežnar and E Nobile
The paper presents numerical simulations of flow in a model of a high head Francis turbine and comparison of results to the measurements. Numerical simulations were done by two CFD (Computational Fluid Dynamics) codes, Ansys CFX and OpenFOAM. Steady-state simulations were performed by k-ɛ and SST model, while for transient simulations the SAS SST ZLES model was used. With proper grid refinement in distributor and runner and with taking into account losses in labyrinth seals very accurate prediction of torque on the shaft, head and efficiency was obtained. Calculated axial and circumferential velocity components on two planes in the draft tube matched well with experimental results.
Full-text can be found here.