Because of the suction and discharge liquid inlet pressure, the impeller on both sides of the impeller is not completely symmetrical, which is not completely symmetrical, thus producing the axial force of the centrifugal pump. If the two sides of the impeller shaft liquid pressure regardless of cross-sectional area, also did not consider the impeller rotation effect on pressure distribution, the role of force on the impeller wheel force difference and wheel cover force, into the formula is the product of the outlet pressure and the inlet pressure difference and the impeller wheel cover area, because the outlet pressure is always greater than the inlet pressure, so when the pump rotation will have a direction along the axis and the force acting on the rotor entrance.
Unbalanced axial force will increase the working load of thrust bearing, bearing disadvantage, at the same time the axial force of the pump rotor to the suction inlet, causing vibration and may cause the impeller mouth ring friction pump damage.
For multi-stage centrifugal pump, the general export pressure is much greater than the inlet pressure, so the balance to eliminate the axial force is particularly important, how to eliminate the axial force it? Multi stage pumps are generally used to balance the disk and the symmetrical installation of the impeller, a single-stage pump is generally open balance holes on the impeller, of course, there is a way to balance the axial force in the impeller wheel disc mounted on the wheel.
Although we ask for is to eliminate the axial force, but if the complete elimination of the rotor can also cause instability in the rotation, so when the design will be designed for bearing capacity of 30% to offset, which is why many pump non drive end bearings are usually angular contact bearings, because it can be used to the axial force is great.
