CaltechTHESIS
  A Caltech Library Service

Cavitation induced instabilities associated with turbomachines

Citation

Braisted, David Miner (1980) Cavitation induced instabilities associated with turbomachines. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-04232004-091330

Abstract

Cavitation induced instabilities of hydraulic systems were investigated both experimentally and analytically. The instability, known as auto-oscillation, was found to occur in a well defined region of cavitation numbers just above head breakdown of the inducer. Auto-oscillation is characterized by large amplitude fluctuations in the pressures and mass flow rates throughout the system. The frequency of the oscillations was observed to decrease with a reduction in both the flow coefficient and cavitation number. The amplitudes of the fluctuation increased with a reduction in the flow coefficient. These detailed measurements reflect changes in the dynamic performance of the inducer due to cavitation and the interaction between the dynamics of the inducer and those of the inlet flow field. Some detailed analytical studies were performed to try to understand the nature of this interaction. A linear stability analysis was developed which was based upon the understanding that auto-oscillation is a function of the entire hydraulic system including the cavitating inducer. Using the experimentally obtained transfer functions of two impellers, the analysis successfully predicted both the onset and frequency of auto-oscillation. The stability of the Dynamic Pump Test Facility is significantly reduced by the increased dynamically active character of the inducers at the lower cavitation number. In addition, the stability of the Dynamic Pump Test Facility was found to be particularly sensitive to the mass flow gain factor and pump impedance.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Mechanical Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Brennen, Christopher E.
Thesis Committee:
  • Unknown, Unknown
Defense Date:29 August 1979
Record Number:CaltechETD:etd-04232004-091330
Persistent URL:http://resolver.caltech.edu/CaltechETD:etd-04232004-091330
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1470
Collection:CaltechTHESIS
Deposited By: Imported from ETD-db
Deposited On:23 Apr 2004
Last Modified:26 Dec 2012 02:38

Thesis Files

[img]
Preview
PDF (Braisted_dm_1980.pdf) - Final Version
See Usage Policy.

8Mb

Repository Staff Only: item control page