Methods of balancing axial force
(5) balance axial force with balance drum
Methods of balancing axial force

(6) Balance the axial force by the method of balance disc.

Radial thrust： Increase the burden on the shaft，deform and even fracture，vibration，reduce the life of pumps
Balance or reduce of hydraulic forces


(7) Balance the axial force by the method of a balance hole or equilibrium tube。
radial force of centrifugal pumps
潘同建
Causes of radial force

the pressure in the volute is basically uniform. Deviating from the optimal conditions will cause the liquid absolute velocity of the impeller outflow deviated from the liquid velocity in volute.Pressure distribution in the volute is uneven.

Structure of centrifugal pumps
Reasons of the hydraulic forces Effects of hydraulic forces Balance or reduce of hydraulic forces



Structure of centrifugal pumps
Causes of axial force

（ 1 ） The area of the liquid pressure on the front and back cover of the pump impeller is not equal, and the distribution of the liquid pressure around the pump chamber is also asymmetric.


For rale-stage pump, use double volute（双蜗壳） 2、Pressurized water chamber

are arranged by 180°
Axial force of centrifugal pumps
For axial thrust： 1、Use the impeller symmetry to counterpoise （双吸泵） 2、Change the shape of the impeller （背叶片） 3、Use thrust bearing（推力轴承） 4、Balancing device（平衡盘、平衡鼓、两者结合）
Radial thrust on the impeller 1.When the Centrifugal pump is under the optimal conditions,
small flow rate：C2>C
big flow rate
：C2<C
C — Flow velocity in the volute
Reasons of the hydraulic forces

For axial thrust： 1、Force difference between hub and shroud 2、Dynamic reaction force

3、For vertical pumps ， gravity is the part of axial thrust.
Methods of balancing axial force

(1) balance axial force of centrifugal pump with a thrust bearing

(2) balance axial force with the back (deputy) vane
Big flow rate
Small flow rate

Pump gravity

The forces including the radial forces on the impeller and pump gravity cause alternating stress acting on shaft and generate directional deflection.
Axial centrifugal force generated causes
(3) The axial force, which is caused by the axial force and the axial end of the shaft, is determined by the specific circumstances. (4) The axial force caused by the weight of the rotor is related to the arrangement of the rotor.
2.Dynamic reaction force
The uneven distribution of liquid pressure around the impeller destory Axisymmetric flow.The pressure of a large liquid flow from the impeller is less.
王琪
Definition of axial force
when the centrifugal pump is in operation, a strong force will generate on its rotor, since the centrifugal force direction parallel to the axis of the shaft, so we called it axial force.
Axial centrifugal force generated causes
(2 Liquid flows from the impeller inlet and flows out from the impeller outlet ， whose speed and direction are not the same,so the axial component of the liquid momentum changed.
Hydraulic forces and balances in centrifugal pumps
members：钱培、范佳晨、陈桢、王琪、潘同建
Brief introduction of centrifugal pumps

陈桢
Brief introduction of centrifugal pumps
Methods of balancing axial force

3) balance axial force with double suction impeller. Due to the symmetrical structural, double suction impeller can balance the axial force. (4) balance axial force with an impeller arranged symmetrically
For radial force:



1、Deviate from the designed point
2、Dynamic reaction force 3、Horizontal pumps，gravity
Effects of hydraulic forces

Axial thrust： 1、large axial thrust，shaft hard to bear 2、Vibration，abrasion
Balance the radial force

single-stage volute pump
Double-volute or Diffuser

multistage centrifugal pump
upside-down volute
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