Imported blades improve cavitation

This post was last posted by 3983596_Edited by FPPZ on 2019-3-13 07:48 The main function of grinding the inlet blades is to increase the inlet liquid cross-sectional area and reduce the flow rate to obtain the minimum pressure drop and reduce the pump NPSH. This is mainly for impellers with a large number of blades and serious crowding of inlet blades. However, it cannot be ground too much, which will lead to insufficient blade extension and late work of the blades, which will affect the cavitation margin. Few or no blades are removed at the front cover, and more blades are removed at the rear cover. This is the so-called backswept type. However, the size of the removed blades depends on the actual shape of the inlet blades. Regardless of the forward and backward sweeps, the principle is to expand the liquid-passing area of ​​the blade inlet, which is based on experience. Pay attention to the rounding of the inlet edge of the blade after grinding. After grinding, the pump flow rate increases, and the NPSH of the original rated point flow rate will decrease slightly. The previous forward-swept picture (limited by grinding tools), this is mainly to increase the flow rate rather than reduce the NPSH.

Thanks to the moderator for answering. Is the black part in the picture above the area to be polished? In other words, increasing the entrance area is the first choice. Are there any other options? Thanks

Well, this is the grinding when the inlet is clogged. When the size is reached, grinding to reduce the cavitation margin can remove and thin the inlet blade thickness from the working surface of the blade to the back. Do not thin the blade thickness on both sides evenly. Then, improve the process parameters and increase the cavitation margin of the device (adjust the inlet pipeline valve, etc.) to reduce the tendency of cavitation.