Impeller cutting amount
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I tested a centrifugal pump yesterday; its impeller diameter is 250, and the required head is 70. After testing, the head was 79. Using the formula for calculating head, the diameter of the impeller after cutting should be 235. But the experienced worker said that according to experience, 1 mm of cutting amount corresponds to 1 meter; about 8 mm was cut, resulting in a diameter of 242. I looked up information at night and found the experience correction formula shown in the figure below; the results obtained using that formula were similar to those given by the experienced workers. I would like to ask what the applicable conditions are for this empirical algorithm – is it suitable for all centrifugal pumps?
The experienced teacher is right; it’s also related to the specific speed
When the cutting amount is small, it’s fine to use the formula directly. However, in your case the cutting amount is quite large, so it’s necessary to apply empirical coefficients for correction, or cut in two steps. You can also use the curves provided by the manufacturer – select the appropriate curve corresponding to the impeller diameter and perform interpolation
Cut it to 235mm – that’s a bit short; based on experience, it should be 240mm
OP, what is the title of your book? Sharing here, I’m a beginner learning *Thank you!
\"Modern Pump Theory and Design\", authored by Guan Xingfan; there is a PDF version available online. I purchased a printed copy, in two volumes.
Calculated as: a diameter of 237.774181806 mm to 234 mm
Calculated as: a diameter of 237.774181806 mm to 238 mm