Abstract

In recent years three workers have described methods of measurement of unsteady flow quantities in water using unpolarized electrodes. Both Binder and Chuang have attempted measurements of turbulent velocity fluctuations, whereas Dumargue described a method of fluctuating pressure measurement.

In this paper, analysis and experiment were used to critically compare the previous workers' experiments. From measurements in an oscillating Poiseuille pipe flow it is concluded that an electrode positioned in the wall detects a signal with a phase angle of π/4 ahead of the fluctuating velocity as measured by a hot-film probe in the pipe center. This is exactly the result predicted by theory for the velocity near the wall. Thus it may be inferred that in this configuration the unpolarized electrode is a velocity transducer and therefore substantiates the work of Binder and Chuang.

Corrections are suggested for Binder's and Chuang's equations and it is deduced that the assumption made by all previous workers, namely that the charge density has a one-dimensional distribution depending only on the distance from the probe surface, could be in error. However, a one-dimensional charge distribution is necessary for Dumarque's electrode to respond to pressure alone.

Meeting Name

Symposium on Turbulence in Liquids (1971: Oct. 4-6, Rolla, MO)

Department(s)

Chemical and Biochemical Engineering

Document Type

Article - Conference proceedings

Presentation Type

Contributed Paper

Session

New Measurement Techniques

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 1972 University of Missouri--Rolla, All rights reserved.

Publication Date

06 Oct 1971

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