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Model predictions and experimental results for the rotordynamic characteristics of leakage flows in centrifugal pumps

Guinzburg, Adiel and Brennen, Christopher E. (1993) Model predictions and experimental results for the rotordynamic characteristics of leakage flows in centrifugal pumps. In: Proceedings of the Tenth International Pump Users Symposium. Texas A&M University , College Station, TX, pp. 41-48. http://resolver.caltech.edu/CaltechAUTHORS:20111226-134646361

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Abstract

The role played by fluid forces in determining the rotordynamic stability and characteristics of a centrifugal pump is gaining increasing attention. The present research investigates the contributions to the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing. An experiment was designed to measure the rotordynamic shroud forces due to simulated leakage flows for different parameters such as flowrate, shroud clearance, face seal clearance, and eccentricity. The functional dependence on the ratio of whirl frequency to rotating frequency (termed the whirl ratio) is very similar to that measured in experiments and similar to that predicted by the theoretical work of Childs [1]. Childs' bulk flow model yielded some unusual results including peaks in the rotordynamic forces at particular positive whirl ratios, a phenomenon which Childs tentatively described as a "resonance" of the leakage flow. This unexpected phenomenon developed at small positive whirl ratios when the inlet swirl velocity ratio exceeds about 0.5. Childs points out that a typical swirl velocity ratio at inlet (pump discharge) would be about 0.5 and may not, therefore, be large enough for the resonance to be manifest. To explore whether this effect occurs, an inlet guide vane was constructed which introduced a known amount of swirl into the flow upstream of the leakage flow inlet. A detailed comparison of model predictions with the present experimental program is presented. The experimental results showed no evidence of the "resonances," even at much larger swirl inlet velocities than explored by Childs.


Item Type:Book Section
Additional Information:The authors would like to thank A.J. Acosta and T.K. Caughey for their support and F. Zhuang, A. Bhattacharyya, F. Rahman, and Sandor Nagy for their assistance with the experiments. They would also like to thank NASA George Marshall Space Flight Center for support under Grant NAG8-118.
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NASANAG8-118
Record Number:CaltechAUTHORS:20111226-134646361
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20111226-134646361
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:28597
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:03 Jan 2012 15:45
Last Modified:26 Dec 2012 14:39

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