LIQUID-LIQUID VORTEX RINGS - HYDRODYNAMICS AND MASS-TRANSFER

Vortex rings have been formed at a tube (5.06 cm or 6.98 cm internal d iameter) in a 20 cm deep layer of kerosene and projected vertically do wnwards through an interface and into 70 cm depth of water. These kero sene-in-water rings with initial volume in the order of 300 ml have be en observed by video camera. The rapid rotation (vorticity) is concent rated in a toroidal region, but the transported volume of kerosene has an oblate spheroidal shape enclosing the toroid. The volume decays ex ponentially by a wake shedding process and the decay constant is relat ed to density difference and ring velocity by a simple model. The extr action rate of benzoic acid (kerosene to water) has been measured unde r batch conditions. The drops which detach in the wake are large so th e extraction efficiencies are relatively low. Efficiency is increased when the vortex rings have sufficent energy to impact on the base of t he tank to form fine droplets.