How to Improve the Cavitation Resistance of Centrifugal Pumps

I. Measures to Increase the Effective Net Positive Suction Head (NPSHₐ) of the Liquid Inlet Device

1. Modify the suction lift device to a flooded suction device.
2. Reduce the installation height of the pump in the suction lift system.
3. Increase the pressure of the liquid level in the storage tank upstream of the pump to improve the effective net positive suction head.
4. Minimize the flow loss in the pipeline upstream of the pump. For example: shorten the pipeline as much as possible within the required range, reduce the flow velocity in the pipeline, minimize the number of elbows and valves, and keep the valve opening as large as feasible.

II. Measures to Enhance the Cavitation Resistance of the Centrifugal Pump Itself

1. Optimize the structural design from the pump suction port to the impeller area:
   • Increase the flow area;
   • Increase the radius of curvature of the impeller cover at the inlet section to reduce sudden acceleration and pressure drop of the liquid flow;
   • Appropriately reduce the thickness of the impeller blade inlet and round the blade inlet to a streamline shape, thereby reducing the acceleration and pressure drop around the blade tip;
   • Improve the surface finish of the impeller and blade inlet area to minimize resistance loss;
   • Extend the blade inlet edge toward the impeller inlet to allow the liquid flow to receive work in advance and increase pressure.
2. Adopt a double-suction impeller. Allowing liquid to enter the impeller from both sides doubles the inlet cross-sectional area and halves the inlet flow velocity.
3. Install a pre-installed inducer to enable the liquid flow to receive work in the inducer in advance, thereby increasing the liquid pressure.
4. Use cavitation-resistant materials. Practice has shown that materials with higher strength, hardness, toughness, and better chemical stability exhibit stronger cavitation resistance.
5. Adopt a slightly larger positive attack angle under design conditions to:
   • Increase the blade inlet angle and reduce the curvature at the blade inlet;
   • Alleviate blade blockage and expand the inlet area;
   • Improve operating conditions under high flow rates to reduce flow loss.

     Note: The positive attack angle should not be excessively large, as it may affect efficiency.