Measurement of the surface ages of water jets

Abstract

Experimental values of the surface velocities us 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/u, 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 Re, = 18 800. This we ascribe to liquid circulation in the jet adjacent to the nozzle, caused by the Marangoni surface flow, which also reduces us significantly. Ages

Trace gas exchange at the air/water interface: Measurements of mass accommodation coefficients

“…They were determined subject to the assumption that the surface speed Us was equal to the average speed (U) of the jet. Liquid jets have been extensively used to determine diffusion coefficients of pure gases in liquids (Raimondi and Toor, 1959;Danckwerts, 1970), and the problem of the true surface speed Us has been repeatedly assessed (Brignole and Echarte, 1981;Davies and Makepeace, 1978). Until recently, only very approximate solutions of the NavierStokes equation pertaining to the velocity distribution of relatively thick and slow liquid jets were available (Scriven and Pigford, 1959;Middleman, 1964;Davies and Makepiece, 1978).…”

Gas entrainment rate and flow pattern of vertical plunging liquid jets

“…Important factors that cannot be overlooked are differences in the nozzle design (McCarthy andMolloy, 1974: Davis andMakepeace, 1978;Van de Donk, 1981) and the nozzle length, L, (Henderson et al, 1970;Cumming, 1975: Funatsu et al, 1988bBin, 1988). They are: nozzle diameter, nozzle velocity, nozzle height and nozzle inclination angle.…”

A New Technique for the Measurement of the Dynamic Evolution of Surface Tension

“…where Equations [12] and [14] each give surface tension as a function of axial distance z down the jet. This distance is in turn related to surface age T through…”

“…[14]). Figure 11 displays both the surface tension σ 1 and the surface tension σ 2 for experiment 1, together with the equilibrium surface tension measured with static techniques, and Fig.…”

“…The spikes are unavoidable, given the numerical division in Eqs. [12] and [14] by a quantity passing through zero. The degree of nonconstancy of σ 1 , σ 2 , and σ (T ) between the spikes is an indication of the limitations of the 8-year-old video and edge detection technology we employed for the measurements of this paper; improvements in the resolution of the video images will result in a narrowing of the spikes in the prediction of surface tension as a function of surface age, and a flattening of the function between the spikes.…”