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Measurement of the surface ages of water jets

Authors

  • J. T. Davies,

    Corresponding author
    1. Department of Chemical Engineering, University of Birmingham, Birmingham B15 2TT, England
    • Department of Chemical Engineering, University of Birmingham, Birmingham B15 2TT, England
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  • R. W. Makepeace

    1. Department of Chemical Engineering, University of Birmingham, Birmingham B15 2TT, England
    Current affiliation:
    1. Fire Research Station, Borehamwood, Herts, WD6 2BL, England
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Abstract

Experimental values of the surface velocities vs of water jets have been obtained by high speed flash cine photography of talc particles on the surfaces of both laminar and turbulent jets. Values of the surface ages as defined variously by Defay and Hommelen (1958), Hansen (1964), and Harper (1973) have been obtained from our data for both pure water and for dilute solutions of surface active agents.

We find, by comparison with published entry length corrections for gas absorption, that x/vs gives the most reasonable age of the surface at any distance x along a jet of pure water.

If a surface active agent is present in the water, the amount of adsorption of a few millimeters downstream from the nozzle is of the order ten times greater than calculated for laminar jets and five to six times greater than calculated for turbulent jets at Ren = 18 800. This we ascribe to liquid circulation in the jet adjacent to the nozzle, caused by the Marangoni surface flow, which also reduces vs significantly.

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