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Friction and Heat Transfer Reduction in Turbulent Flow of Dilute Asbestos Fiber Suspensions in Smooth and Rough Tubes

Citation

Moyls, Adrian Leigh (1976) Friction and Heat Transfer Reduction in Turbulent Flow of Dilute Asbestos Fiber Suspensions in Smooth and Rough Tubes. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:02022017-132608721

Abstract

Friction and heat transfer coefficients were obtained in turbulent flow of dilute asbestos fiber suspensions through a smooth and a rough tube. The 3/8 inch nickel tubes were heated electrically. Suspensions of 50,300 and 600 ppm asbestos fibers were used at Prandtl numbers of approximately 2, 6 and 11. These were obtained by varying the bulk temperature of the suspension. The surface of the rough tube consisted of a close-packed, granular type of roughness with a height-to-diameter ratio of 0.488. The Reynolds number range studies varied from 10,000 (Pr = 11) to 500,000 (Pr = 2).

Maximum friction reductions of 76% in the smooth tube and 87% in the rough tube were observed, along with even greater reductions in heat transfer rates, namely 86% in the smooth tube and 95% in the rough tube. (Heat transfer coefficients with asbestos fibers can be lower in a rough tube than in a smooth tube.) In the present series of experiments the mechanism by which the fibers interfere with the flow lost its effectiveness at high Reynolds numbers.

The data was analyzed in light of analyses developed previously for Newtonian fluids and extended to dilute fiber suspensions. The results indicate that the turbulent diffusivities are reduced in the wall region and bring about a thicker viscous layer.

The most plausible mechanism which may explain the action of the fibers envisions interference of the fibers with the so-called "bursts" which are known to originate in the viscous layer.

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):
  • Sabersky, Rolf H.
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 April 1976
Funders:
Funding AgencyGrant Number
Shell Companies FoundationUNSPECIFIED
NSFUNSPECIFIED
Record Number:CaltechTHESIS:02022017-132608721
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:02022017-132608721
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10044
Collection:CaltechTHESIS
Deposited By: Benjamin Perez
Deposited On:07 Feb 2017 16:26
Last Modified:07 Feb 2017 16:26

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