The harm of the vaporization of the pump and the harm of the vaporization of the pump
1. produce noise and vibration
Because the pump vaporization of space-time foam in high pressure area continuous rupture accompanied by strong water hammer, water vaporization is thus harm will produce noise and vibration, can be heard like popcorn like the crackling sound, which can roughly determine whether vaporization occurred in this case, the injection of a small amount of air can buffer the vibration and noise of destruction metal, this method in hydraulic turbine has been widely used, but rarely used in the pump.
2. overflow component cavitation
When the pump works for a long time under the conditions of vaporization, some parts of the pump flow component will be vaporized, that is, cavitation. This is because of vaporization
On the metal surface when the pump vaporization will harm the metal surface have a strong impact as the blade like, the metal will appear that pitting perforation. Sometimes the metal particles are loose and flaking and appear honeycomb. In addition to the mechanical force, the cavitation is accompanied by a variety of complex functions, such as electrolysis and chemical corrosion.
It has been proved that the cavitation is the place where the cavitation is broken. So often in the round and later imported water pressure chamber of imported parts found traces of cavitation, but the vaporization produced in the impeller inlet to prevent cavitation in radical vaporization to the impeller inlet.
3. performance decline
When the pump is vaporized, the energy exchange between impeller and liquid is disturbed and destroyed. The external characteristics are the lift flow curve, the shaft power and the flow curve, and the efficiency flow curve descends. In serious case, the fluid in the pump will be interrupted and the pump can not work. But there is no obvious change in the performance blue line at the initial stage of the pump vaporization. When the performance curve changes, the vaporization has developed to a certain degree.
The performance curves of different specific speed pumps are different in the form of vaporization. For low specific speed pumps, due to the narrow and long blade channels, once vaporization vacuoles are easy to fill the whole flow path, the danger of pump vaporization is a sharp decline in performance curve. With the increase of specific speed, the flow path of blade becomes wider and shorter. Therefore, the development of cavitation from primary to full flow path has a transient process, and the corresponding pump performance curve begins to slow down. The performance curve of the axial flow pump is only slow down in the whole flow range. In addition, the vaporization of the multistage pump is only limited to first levels, so the performance decline is smaller than the single stage single suction centrifugal pump.
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