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On the improvement of permeability assessment of fibrous materials
Sharma, Sanjay
Sharma, Sanjay
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Dissertation
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2010-05
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Electronic dissertations
Electronic dissertations
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Abstract
The focus of this work is to understand the current state of permeability measurement and
prediction methods for fibrous, porous media and to suggest improvements. For this purpose the
most widely used and accepted measurement technique, the channel flow method, is used to
experimentally investigate the effects of fiber sizing and fluid viscosity on the permeability of
glass and carbon fibers.
Experiments have shown that the variation in permeability occurs due primarily to the
fluid viscosity and not the nature of fluid, which other researchers have proposed. Studies were
also carried out on both sized and unsized fibers to show that significant permeability variation
occurs when fluids of different viscosity are used. Further, experimental studies on the effect of
secondary flow have revealed that, for fiber products representative of the aerospace industry,
secondary flow has little effect, which challenges models proposed by other researchers.
Previous studies had shown a dual scale flow for fiber products with a significantly lower fiber
volume fraction.
A novel acoustical method based on standardized impedance tube measurements has
been developed to predict physical properties—both permeability and characteristic length—of
the porous medium. The predicted permeability values from the acoustical method for the range
of porosity studied in this work compare well enough with existing permeability models’
predictions to warrant further study. The acoustical method is quick and repeatable, and when
compared with the existing flow methods may provide a convenient alternative. It also provides
a measure of fiber arrangement (via the “viscous characteristic length”) that should be studied
further to explain variations in permeability measurements due to alternative fiber product
architecture.
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Thesis (Ph.D.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
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Wichita State University
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Copyright Sanjay Sharma, 2010. All rights reserved