Abstract: In order to design reasonably the structure parameters of balance disc in multi-stage pump, and solve the vibration problem caused by the excessive pulsation during the working process of balance disc, the dynamic balance process of balance disc is studied. Based on the structure feature that radial gap and axial gap in balance disc are narrow and long, the flows in the two gaps are analyzed respectively, and the function expression of dynamic balance force is deduced by using continuity equation and momentum equations. Then the motion equation about the balance disc-rotor system is established, and combined with the example the working process of balance disc is simulated numerically by using this equation. The simulation results indicate that the axial pulsation of the balance disc-rotor system achieves stability in a very short period of time and presents a cyclical change rule, which is consistent with the real working process of balance disc, and proves that using the deduced motion equation to describe the dynamic balance characteristics of the balance disc in multi-stage pump is feasible.

Key words: Axial displacement, Axial velocity, Balance disc, Balance force, Dynamic equilibrium