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Behavior of spherical particles at low Reynolds numbers in a fluctuating translational flow

Citation

Hill, Murray Keith (1973) Behavior of spherical particles at low Reynolds numbers in a fluctuating translational flow. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:11132015-144035933

Abstract

The behavior of spheres in non-steady translational flow has been studied experimentally for values of Reynolds number from 0.2 to 3000. The aim of the work was to improve our qualitative understanding of particle transport in turbulent gaseous media, a process of extreme importance in power plants and energy transfer mechanisms.

Particles, subjected to sinusoidal oscillations parallel to the direction of steady translation, were found to have changes in average drag coefficient depending upon their translational Reynolds number, the density ratio, and the dimensionless frequency and amplitude of the oscillations. When the Reynolds number based on sphere diameter was less than 200, the oscillation had negligible effect on the average particle drag.

For Reynolds numbers exceeding 300, the coefficient of the mean drag was increased significantly in a particular frequency range. For example, at a Reynolds number of 3000, a 25 per cent increase in drag coefficient can be produced with an amplitude of oscillation of only 2 per cent of the sphere diameter, providing the frequency is near the frequency at which vortices would be shed in a steady flow at the mean speed. Flow visualization shows that over a wide range of frequencies, the vortex shedding frequency locks in to the oscillation frequency. Maximum effect at the natural frequency and lock-in show that a non-linear interaction between wake vortex shedding and the oscillation is responsible for the increase in drag.

Item Type:Thesis (Dissertation (Ph.D.))
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):
  • Zukoski, Edward E. (advisor)
  • Marble, Frank E. (co-advisor)
  • Rannie, W. Duncan (co-advisor)
Thesis Committee:
  • Unknown, Unknown
Defense Date:13 September 1972
Funders:
Funding AgencyGrant Number
Imperial Oil of Canada, Ltd.UNSPECIFIED
CaltechUNSPECIFIED
Aerospace Research Laboratories (AFSC)UNSPECIFIED
Record Number:CaltechTHESIS:11132015-144035933
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:11132015-144035933
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9280
Collection:CaltechTHESIS
Deposited By: Benjamin Perez
Deposited On:13 Nov 2015 23:24
Last Modified:13 Nov 2015 23:40

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