Numerical simulation and analysis of pressure pulsation in Francis hydraulic turbine with air admission

In this paper,the three-dimensional unsteady multiphase flow is simulated in the whole passage of Francis hydraulic turbine.The pressure pulsation is calculated and compared with the experimental data at positions in the draft tube,in front of runner,guide vanes and in the inlet of the spiral case.The relationship between pressure pulsation in the whole passage and air admission is analyzed. The computational results show that air admission from spindle hole decreases the pressure difference in the horizontal section of draft tube,which decreases the amplitude of low-frequency pressure pulsation in the draft tube;the interaction between the air inlet and the runner increases the middle-frequency pressure pulsation in front of the runner.