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Experimental Measurements of Hydrodynamic Radial Forces and Stiffness Matrices for a Centrifugal Pump-Impeller

Chamieh, Dmitri S. and Acosta, Allan J. and Brennen, Christopher E. and Caughey, Thomas K. (1985) Experimental Measurements of Hydrodynamic Radial Forces and Stiffness Matrices for a Centrifugal Pump-Impeller. Journal of Fluids Engineering, 107 (3). pp. 307-315. ISSN 0098-2202.

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The present work is an experimental investigation of the possible forces of fluid dynamic origin that can act on a turbomachine rotor particularly when it is situated off its normal center position. An experimental facility, the Rotor Force Test Facility, has been designed and contructed in order to measure these kinds of forces acting on a centrifugal pump impeller when the latter is made to whirl in a slightly eccentric circular orbit. The scope of the present experimental work consists of measuring quasi-steady forces on the impeller as it whirls slowly about the axis of the pump rotation. These forces are due to interaction between the impeller and volute; they are decomposed into force components relative to the geometric center of the volute and to those proportional to displacent from this center. These latter are interpreted as stiffness matrices. Such matrices were obtained for two different volutes and both were found to be the sum of a diagonal and a skewsymmetric matrix. It can be shown that a stiffness matrix of this type can lead to dynamic instability of impeller shaft system in certain circumstances. This new experimental finding may explain some operational problems of "high-speed" hydraulic machinery. Comparison is made with various existing theoretical and experimental results.

Item Type:Article
Additional Information:Contributed by the Fluids Engineering Division for publication in the Journal of Fluids Engineering. Manuscript received by the Fluids Engineering Division, April 2, 1984. This work was sponsored by the National Aeronautics and Space Administration under contract no. NAS8-33108 and by a Byron Jackson Fellowship in Fluid Machinery. This support is gratefully acknowledged.
Issue or Number:3
Record Number:CaltechAUTHORS:CHAjfe85
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:81
Deposited By: Christopher Brennen
Deposited On:17 Sep 2004
Last Modified:02 Oct 2019 22:16

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