Performances of centrifugal pumps of very low specific speed

Kurokawa, Junichi
Matsumoto, Kazunari
Matsui, Jun
Kitahora, Takaya

Publication date

January 1999

Publisher

International Association of Hydraulic Research (IAHR)

Abstract

Pump efficiency drops rapidly with a decrease in specific speed Ns in the very low Ns range. In order to improve a pump efficiency and to establish the optimum design method of a very low specific speed pump in the range of Ns<100 [rpm,m3/min, m], eight kinds of centrifugal impellers were tested in the same volute casing designed at Ns -60. Three impellers have the same outlet angle of β2=22.5° with a different Ns ranging from 80 to 200, and the other five have radial vanes(β2=90°) from Ns=50 to 80.The results showed that the conventional design is not suitable for a very low Ns Pump and that the maximum efficiency is largely influenced by the volute design parameters, such as a volute tongue, a olute width and a gap between a impeller exit...