Loss Analysis and Performance Improvement of Very Low Specific Speed Centrifugal Pumps
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In the range of very low specific speed ns, improvement of efficiency is the most important subject in order to apply turbo machine to such a low specific speed range. The purpose of the present study is focused on the performance improvement of pump in the range of ns≦80[m,m3/min,min-1], and CFD simulation is performed to determine the reason why efficiency is very low. Moreover, in order to obtain very low specific speed impeller with high efficiency, a new type centrifugal impeller with radial grooves mounted at the back of both front and rear shrouds is simulated and tested to reveal the performance improvement. The result shows that a rapidly increase of leakage rate and disk friction rate with a decrease of ns is the main reason of law efficiency. Also, the result shows that if the leakage loss is reduced by use of Labyrinth seal at ns=25, the disk friction rapidly increases in spite of the leakage reduction and pump overall efficiency becomes only 5% higher. Moreover, the new type impeller with grooves produces very high-head compared with that of normal impeller at ns=80.
- Proceedings of the 23rd IAHR Symposium on Hydraulic Machinery and Systems, Yokohama, October 2006
Proceedings of the 23rd IAHR Symposium on Hydraulic Machinery and Systems, Yokohama, October 2006, 2006
International Association of Hydraulic Research (IAHR)