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Electrochemical measurement of velocity gradient at the wall of a helical tube
Author(s) -
Galier Sylvain,
Issanchou Sébastien,
Moulin Philippe,
Clifton Michael J.,
Aptel Philippe
Publication year - 2003
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690490807
Subject(s) - laminar flow , turbulence , mechanics , electrode , shear rate , tube (container) , diffusion , volumetric flow rate , chemistry , materials science , geometry , analytical chemistry (journal) , thermodynamics , physics , composite material , chromatography , viscosity , mathematics
An electrochemical technique was used for measuring the wall velocity gradient in two coiled pipes: a torus and a helix. An electrochemical oxidation reaction was employed with its rate limited by mass transfer. Measurement of the diffusion‐limited current at a microelectrode embedded flush with the wall allows the wall shear rate to be determined. The flow velocity was varied through both the laminar and turbulent regimes. Measurements were made for different electrode positions on the pipe circumference and, as expected, the highest shear rate was found at the outside of the curve, with the lowest value at the inside. In the case of the helical pipe, maxima and minima in shear rate were shifted slightly away from the positions observed for the torus.