Expand the partition opening to increase flow rate
Thread Content
Gentlemen, our former designer, in order to increase the design flow rate of the pump, enlarged the opening of the partition ridge on the ZA50-315 pump body and ground away a section of that partition ridge to boost the pump’s design flow rate. I would like to ask those of you who may have experience with such modifications: what were the results, and what was the basis for making these changes?
It does work, but there isn’t much evidence to support how effective it is
This post was last edited by 3983596_FPPZ on 2018-10-22 at 15:45 to continue following up from the previous post. First test: This pump, ZA50-315, has a rated flow rate of 95 and a rated head of 117. During testing, it exhibited significant vibration, and its net positive suction head was above the specified value (3.0, while the actual value was 3.5). Second test: It was suspected that the pump’s flow area was insufficient, and the pump was operating at high flow rates; therefore, the partition within the pump was ground down and the areas of the volute and the outlet diffuser were enlarged. Vibration levels did not improve after this test, and no measurement of the net positive suction head was taken. Third test: The flow area of the pump casing was increased, which led to the assumption that the problem lay with the impeller, as the inlet area of the impeller is the smallest among all the areas through which fluid passes; this restriction was the cause of the issue. Therefore, the inlet blades of the impeller were ground, with the working surface side of the blades being thinned in order to reduce congestion at the inlet, increase the flow area, raise the inlet angle, enhance the performance at the inlet, and lower the net positive suction head. During the test, the vibration at the specified point met the requirement (decreasing from 4.2 to 2.5), while the net positive suction head was slightly higher by 3.2 compared to the specified value. It proves that repairing the impeller worked. Fourth test: Head deviation is 132; the impeller was cut (using Sulzer’s formula, which is conservative). Work is ongoing on further sharpening the inlet blades of the impeller, shortening them slightly backward to increase the flow area further; the blades remain thin. The process is still in progress. . .
After reading the original poster’s feedback, it seems they put quite a bit of thought into it. However, I prioritize my own understanding and am unable to provide assistance with answers. However, I did a search, and since the beginning of this year, authors have published 5 papers on separator tongues. If the original poster needs further research, they can reply and I’ll help download it for them. Let’s all study and learn together*.
If the moderator is able to download it and share it as material, I will be extremely grateful in my heart:D
At this point, an increase in flow rate can occur on a small scale; it depends on the specific speed. If too much of the blade area is removed, it’s as if part of the impeller has been cut away, and in that case the flow rate remains unchanged. This method does not affect the net positive suction head. Repairing the impeller inlet can indeed improve the net positive suction head.
Downloading such resources is too easy for me. I’ll download it once I’m free later, post a thread for resource sharing, upload the attachment, and reply with the link in this post. To be honest, I don’t usually have time to go looking for various papers; it’s only when someone needs them and I happen to be interested in that area that I help download them and take a look at them. Hahaha,
I found a few articles from the past two years and posted a resource thread, as follows: https://bbs.hcbbs.com/thread-2118459-1-1.html. No need to thank me; just send a flower instead, hahaha