@inproceedings{oai:ynu.repo.nii.ac.jp:00003760,
 author = {Kagawa, Shusaku and Matsui, Jun and Kurokawa, Junichi and Choi, Young-do},
 book = {Proceedings of the 23rd IAHR Symposium on Hydraulic Machinery and Systems, Yokohama, October 2006},
 month = {},
 note = {application/pdf, 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.},
 publisher = {International Association of Hydraulic Research (IAHR)},
 title = {Loss Analysis and Performance Improvement of Very Low Specific Speed Centrifugal Pumps},
 year = {2006}
}