On the performance of a high head Francis turbine at design and off-design conditions

Francis-99 Workshop 1: steady operation of Francis turbines

Aakti, B.^1 ; Amstutz, O.^1 ; Casartelli, E.^1 ; Romanelli, G.^1 ; Mangani, L.^1

Lucerne University of Applied Sciences and Arts Engineering and Architecture, Horw, Switzerland^1

关键词: Best efficiency point;    Different operating conditions;    Incompressible RANS equations;    Numerical predictions;    Off design condition;    Pressure-velocity coupling;    Steady-state simulations;    Workshop organizations;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/579/1/012010/pdf
DOI  :  10.1088/1742-6596/579/1/012010

来源: IOP

【 摘 要 】

In the present paper, fully 360 degrees transient and steady-state simulations of a Francis turbine were performed at three operating conditions, namely at part load (PL), best efficiency point (BEP), and high load (HL), using different numerical approaches for the pressure-velocity coupling. The simulation domain includes the spiral casing with stay and guide vanes, the runner and the draft tube. The main target of the investigations is the numerical prediction of the overall performance of the high head Francis turbine model as well as local and integral quantities of the complete machine in different operating conditions. All results were compared with experimental data published by the workshop organization. All CFD simulations were performed at model scale with a new in-house, 3D, unstructured, object-oriented finite volume code within the framework of the open source OpenFOAM library. The novel fully coupled pressure-based solver is designed to solve the incompressible RANS- Equations and is capable of handling multiple references of frame (MRF). The obtained results show that the overall performance is well captured by the simulations. Regarding the local flow distributions within the inlet section of the draft-tube, the axial velocity is better estimated than the circumferential component.