CHEMICALLY REACTIVE TURBULENT VORTEX RINGS

Employing an aqueous acid-base reaction, the minimum mixing rate of tu rbulent vortex rings was investigated in a water tank. Vortex rings we re generated by a simple apparatus with a cylindrical geometry. The re leased fluid surrounding the vortex core mixed very rapidly when compa red with the fluid in the toroidal core. Moreover, the fluid within th e core did not mix uniformly in the azimuthal direction. The normalize d distance a vortex ring must travel, in order to completely mix with the ambient fluid to a specific volumetric ratio, depends on the aspec t ratio of the generating cylinder. Scaling arguments are presented th at relate the above distance to the spreading rate and the generating apparatus parameters. Due to the very small net entrainment rate of vo rtex rings, the detrainment of core material cannot be ignored when th e mixing rate of the core is considered. (C) 1995 American Institute o f Physics.