Studies on the Behavior of Transient Jets : Measurements of Transient Velocity and Concentration

Abstract

Transient laminar jets of CO₂ were formed in a N₂ stream. Time-and space-resolved measurements of velocity and concentration were made by a laser Doppler velocimeter and a laser Rayleigh scattering method in transient jets together with visual studies by schlieren photography. The results obtained are as follows. (1) Axisymmetric large scale ring vortices are formed successively in the jet and travel downstream. (2) Outward or inward radial flow is observed at the downstream or upstream of each ring vortex, respectively. The vortex has the velocity of solid body rotation in the central part and free-vortex in the outer part of the vortex. (3) the surrounding gas (N₂) is engulfed by the vortex to form the laminated layer which enhances micro-mixing on a molecular scale.