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International Journal of Rotating Machinery
Volume 2008, Article ID 536850, 7 pages
Research Article

Suppression of Performance Curve Instability of an Axial-Flow Pump by Using a Double-Inlet-Nozzle

Pfleiderer-Institut, TU-Braunschweig, Langer Kamp 6, 38106 Braunschweig, Germany

Received 10 April 2008; Accepted 16 June 2008

Academic Editor: Seung Jin Song

Copyright © 2008 P. Pérez Flores et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


It has been shown that the sudden decrease of pump head in an axial flow pump caused by stall can be overcome by means of casing treatment. Flat axial grooves in front of the impeller break the swirl of the near-casing backflow. The disadvantage of this method is strong cavitation at the inlet of the grooves for flow rates below the stall point. In this paper another improved method to stabilize the performance curve will be presented, using a double-inlet-nozzle. At the onset of stall the initial near-casing backflow with its high swirl is lead off into the gap between both nozzles. At design conditions this double-inlet-nozzle is working as an injector, supporting the near-casing-inflow. The function of the double-inlet-nozzle is demonstrated by PIV-measurements.