On the loss fof efficiency of a Francis turbine due to the cavitation phenomenon

Cavitation phenomenon is one of the most important phenomena that can occur in pumps and turbines. This phenomenon is undesirable and harmful in turbines and pumps, as it causes material erosion, reduction in turbo-machine efficiency, and generation of unwanted noise and vibrations. Therefore, designers and operators of turbines and pumps strive to avoid the occurrence of cavitation. The occurrence of this phenomenon in turbines and pumps can take various forms. In this paper, the occurrence of cavitation in a Francis turbine is studied, using the computational fluid dynamics software OpenFOAM. The Q criterion is also used to observe the vapor volume fraction. Validation is performed using existing experimental work. The results indicate that increasing the suction head of the Francis turbine intensifies cavitation and leads to a decrease in its efficiency. Additionally, increasing the mass flow rate of the Francis turbine up to ۲۲ cubic meters per second reduces cavitation, but beyond this value, cavitation increases.

Keywords:

Cavitation , Francis turbine , computational fluid dynamics , loss of efficiency