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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. Engineer's thesis, California Institute of Technology. doi:10.7907/xywm-v650.


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.

Item Type:Thesis (Engineer's thesis)
Subject Keywords:Mechanical Engineering
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Mechanical Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Acosta, Allan J. (advisor)
  • Brennen, Christopher E. (co-advisor)
  • Caughey, Thomas Kirk (co-advisor)
Thesis Committee:
  • Unknown, Unknown
Defense Date:26 May 1989
Record Number:CaltechTHESIS:09292010-111031034
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6075
Deposited On:29 Sep 2010 20:17
Last Modified:22 Apr 2021 23:55

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