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Experimental Investigation of the Hydrodynamic Forces on the Shroud of a Centrifugal Pump Impeller

Zhuang, Fei (1989) Experimental Investigation of the Hydrodynamic Forces on the Shroud of a Centrifugal Pump Impeller. California Institute of Technology , Pasadena, CA.

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Fluid-induced forces acting on a rotating impeller are known to cause rotor-dynamic problems in turbomachines. The forces generated by leakage flow along the front shroud surface of a centrifugal turbomachine impeller play an important role among these fluid-induced forces. The present research was aimed to gain a better understanding of these shroud forces. An experimental apparatus was designed and constructed to simulate the impeller shroud leakage flow. Hydrodynamic forces, steady and unsteady pressure distributions on the rotating shroud were measured as functions of eccentricity, width of shroud clearance, face seal clearance and shaft rotating speed. The forces measured from the dynamometer and manometers agreed well. The hydrodynamic force matrices were found skew-symmetric and statically unstable. This is qualitatively similar to the result of previous hydrodynamic volute force measurements. Nondimensionalized normal and tangential forces decrease slightly as Reynolds number increases. As the width of the shroud clearance decreases and/or the eccentricity increases, the hydrodynamic forces increase nonlinearly. There was some evidence found that increased front seal clearance could reduce the radial shroud forces and the relative magnitude of the destabilizing tangential force. Subharmonic pressure fluctuations were also observed which may affect adversely the behavior of the rotor system.

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Additional Information:Report No. E249.9 on Grant NAG8-118. Thesis by Fei Zhuang In Partial Fulfillment of the Requirements for the Engineer's Degree. I would like to express my gratitude to Professor A. J. Acosta for his guidance and advice during the course of this research. I would also like to thank Professors C. E. Brennen and T . K. Caughey for their continued interest in this research. I would like to thank George Lundgren and his team for the machining of the test apparatus. I am also thankful to Mike Gerfen, who assisted the initial installation of the apparatus. The assistance provided by Ron Franz, Norbert Arndt, Faress Rahman, and Adiel Guinzburg is appreciated. I also want to thank the others not mentioned here for their various contributions to this research. For their help in preparing the thesis, I would like to thank Dana Young and Cecilia Lin. The help of Jackie Beard with the administrative tasks is also appreciated. I gratefully acknowledge the Byron-Jackson Pumps Division for providing a fellowship that supported my graduate studies. This research was supported by NASA George C. Marshall Space Flight Center under contract NAS8-33108 and grant NAG8-118. Finally, sincere thanks go to my parents and my sister for the understanding and the encouragement they have given to me. I dedicate this thesis to my wife, Ying Sun, whose support, caring and inspiration are greatly appreciated.
Funding AgencyGrant Number
Byron-Jackson pumps DivisionUNSPECIFIED
NASA George C. Marshall Space Flight CenterNAS8-33108
NASA George C. Marshall Space Flight CenterNAG8-118
Record Number:CaltechAUTHORS:20140110-152935012
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ID Code:43321
Deposited On:11 Jan 2014 00:11
Last Modified:03 Oct 2019 06:06

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