Simulations of Steady Cavitating Flow in a Small Francis Turbine

الملخص EN

The turbulent flow through a small horizontal Francis turbine is solved by means of Ansys-CFX at different operating points, with the determination of the hydrodynamic performance and the best efficiency point.

The flow structures at different regimes reveal a large flow eddy in the runner and a swirl in the draft tube.

The use of the mixture model for the cavity/liquid two-phase flow allowed studying the influence of cavitation on the hydrodynamic performance and revealed cavitation pockets near the trailing edge of the runner and a cavitation vortex rope in the draft tube.

By maintaining a constant dimensionless head and a distributor vane opening while gradually increasing the cavitation number, the output power and efficiency reached a critical point and then had begun to stabilize.

The cavitation number corresponding to the safety margin of cavitation is also predicted for this hydraulic turbine.