1. Improve the cavitation resistance of the water pump

1. Reduce the necessary cavitation allowance

(1) water pump with double suction impeller. As a result of the double suction pump NPSH Δ hc than single stage single suction pump NPSH Δ hc is small, the speed n the same pump and flow rate Q, as far as possible with double suction impeller.

(2) an induction wheel is installed in front of the impeller. An induction wheel is arranged in front of the impeller of the centrifugal pump. The induction wheel runs with the blade of the pump, and the pressure wheel produced by it runs together after coaxial assembly. The pressure generated by it pressurizes the inlet of the impeller to improve the cavitation resistance of the pump. However, the performance of the pump will be unstable if the induction wheel is installed, so further exploration and research are needed.

(3) appropriately increase the inlet diameter of the impeller and the inlet width of the blade. When the inlet diameter of the impeller and the inlet width of the blade increase, the absolute velocity and relative velocity of the impeller inlet decrease, and it can be seen that the critical cavitation allowance of the pump decreases. At this point, however, the area of the leakage reduction ring at the inlet of the impeller increases and the leakage volume increases, so the volume-displacement efficiency of the pump will decrease.

2, improve the anti-cavitation ability of the parts material in order to reduce the cavitation damage to the parts of the water pump, to extend its service life, often choose the material with strong cavitation resistance. For example, the impeller is cast with manganese, bronze, stainless steel and alloy steel. Or with polymer coating or laser spraying over the surface of the flow parts to resist cavitation damage. In addition, the surface of the flow parts can be refined to improve its finish and reduce the damage of cavitation.

Methods to reduce the cavitation of water pump ii. Improve the anti-cavitation ability of the inlet device

Cavitation allowance is closely related to the inlet device and the piping system, so a good inlet device should be designed to increase the cavitation allowance at the pump inlet as much as possible, so as to meet the requirements of dynamic pressure drop in the pump.

(1) well-designed entry pool. Good water intake can not only reduce the water level drop in the pool, reduce the resistance coefficient of the water inlet, but also the water surface in the pool is stable without vortex. Can avoid the air into the pump to prevent premature cavitation.

(2) reasonably determine the suction height of the pump. Since the pump generally operates under off-design conditions, various working conditions that may be encountered in the work of the pump should be fully considered. The determined suction height should meet the requirements of the pump's suction performance under any working conditions.

(3) reasonable inlet pipe should be selected. As far as possible to reduce the length of the inlet pipe and unnecessary pipe accessories, appropriate increase in the inlet pipe diameter, in order to reduce the hydraulic loss of the inlet pipe, improve the pump inlet cavitation allowance. For large and medium-sized axial pumps, the flow velocity and pressure in the inlet pipe are distributed as evenly as possible, which will be beneficial to prevent cavitation

3. Measures that can be taken in operation management

(1) try to make the pump run in the design condition. According to the specific conditions of the pump station, adjustment measures such as variable valve, variable speed and variable Angle can be adopted to prevent the running condition of the pump from deviating from the design condition too far.