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Electrochemical measurement of velocity gradient at the wall of a helical tube

Authors

  • Sylvain Galier,

    Corresponding author
    1. Laboratoire de Génie Chimique (CNRS UMR 5503), Université Paul Sabatier, 31062 Toulouse Cedex, France
    • Laboratoire de Génie Chimique (CNRS UMR 5503), Université Paul Sabatier, 31062 Toulouse Cedex, France
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  • Sébastien Issanchou,

    1. Laboratoire de Génie Chimique (CNRS UMR 5503), Université Paul Sabatier, 31062 Toulouse Cedex, France
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  • Philippe Moulin,

    1. Laboratoire de Génie Chimique (CNRS UMR 5503), Université Paul Sabatier, 31062 Toulouse Cedex, France
    Current affiliation:
    1. Laboratoire en Procédés Propres et Environnement (LPPE-EA-884), ENSSPICAM, Domaine Universitaire de Saint Jérôme, Av. Escadrille Normandie Niemen, 13397 Marseille Cedex 20, France
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  • Michael J. Clifton,

    1. Laboratoire de Génie Chimique (CNRS UMR 5503), Université Paul Sabatier, 31062 Toulouse Cedex, France
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  • Philippe Aptel

    1. Laboratoire de Génie Chimique (CNRS UMR 5503), Université Paul Sabatier, 31062 Toulouse Cedex, France
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Abstract

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.

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