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Hydrodynamic Impeller Stiffness, Damping, and Inertia in the Rotordynamics of Centrifugal Flow Pumps

Jery, B. and Acosta, A. J. and Brennen, C. E. and Caughey, T. K. (1984) Hydrodynamic Impeller Stiffness, Damping, and Inertia in the Rotordynamics of Centrifugal Flow Pumps. In: Rotordynamic instability problems in high-performance turbomachinery: proceedings of a workshop held at Texas A&M University, May 28-30, 1984. NASA Conference Publication. No.CP-2338. National Aeronautics and Space Administration , Washington, DC, USA, pp. 137-160.

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Measurements were made of the lateral hydrodynamic forces experienced by a centrifugal pump impeller performing circular whirl motions within several volute geometries. Experiments were conducted for various flow coefficients, [phi], impeller rotating speeds or angular frequencies, w, and the angular frequency of the whirl motion, [omega], was varied from zero to nearly synchronous (equation) and to nearly antisynchronous (equation). The lateral forces were decomposed into (i) time averaged lateral forces and (ii) hydrodynamic force matrices representing the variation of the lateral forces with position of the impeller center. No assumptions concerning the form of these matrices need to be made. The latter can be further decomposed according to the variation with whirl frequency, the result being "stiffness", "damping", and "fluid inertial" rotordynamic force matrices. It was found that these force matrices essentially consist of equal diagonal terms and skew-symmetric off-diagonal terms. One consequence of this is that during its whirl motion the impeller experiences forces acting normal and tangential to the locus of whirl. Data on these normal and tangential forces are presented; in particular it is shown that there exists a region of positive reduced whirl frequencies, [omega/w], within which the hydrodynamic forces can be destabilizing with respect to whirl.

Item Type:Book Section
Additional Information:Some preliminary data was released in June 1983. This should now be disregarded; it is superseded by the data of the present paper.
Series Name:NASA Conference Publication
Issue or Number:CP-2338
Record Number:CaltechAUTHORS:JERriphpt84
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:214
Deposited By: Christopher Brennen
Deposited On:10 Dec 2004
Last Modified:02 Oct 2019 22:31

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