A question regarding impeller cutting
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Some impellers need to have beveled edges when cutting the outer circumference, that is, to make the cutting line not parallel to the pump shaft. After checking relevant information, I found that the beveled impeller is related to the specific speed; beveled impellers with medium to high specific speeds can result in a lesser decrease in the pump’s efficiency. But I don’t understand why, if the cover plates are to be kept, the one at the front has to be larger while the one at the back is smaller. Is this related to the inlet pressure of the pump? I hope the experts can provide an explanation
If the water flow pushes backward and what’s behind is sealed, but the front end is not! It’s possible that the water, pushed to the limit, might try to surge in! I’m showing off my skills in front of experts; please, teachers, offer your guidance!
One of the purposes of chamfering is to modify the \"head-flow\" curve, changing it from a poorly controllable inverted U-shaped curve to a more easily controllable gradually decreasing curve. The principle is likely that, at high head and low flow rates, the flow losses are primarily concentrated in the outlet area of the impeller (in contrast, at low head and high flow rates, the flow losses stem mainly from shock waves and local turbulence at the impeller inlet); therefore, removing a portion of the impeller’s outlet can significantly reduce flow losses at high head and low flow rates, thereby increasing the head at those conditions. As for the specific and correct reasons, the technical developers at the pump factory should be quite familiar with them.
The teacher still didn’t explain why the front cover is larger and the back cover is smaller. If the rear cover is larger than the front cover, is there any difference between the two?
An expert has provided the following explanation, which is shared here with all marine enthusiasts: First, the axial force of the pump acts toward the suction side of the impeller; when it reaches the front cover plate, this axial force increases further, affecting the pump’s lifespan. II. Head-flow curve that decreases gradually
Which end is the front cover you are referring to worth?
This post was last edited by 3983596_FPPZ on 2020-4-11 at 11:24. This type of cutting makes the path taken by the liquid through the front and rear cover plates longer and more similar, thereby preventing swirl losses at the outlet due to differences in flow velocity between the front and rear cover plates of the impeller, and avoiding the formation of bulges in the flow pattern