Author(s): C. H. C. Chan; K. M. Lam
Keywords: Jet; Counterflow; Laser induced fluorescence; Concentration field
Abstract: Laser-induced fluorescence (LIF) technique is applied to study the mean concentration field of a circular jet in a counterflow. The experimental results show that the centreline dilution increases with the downstream distance at a rate faster than a jet in stagnant ambient. The dilution rate along the centreline is found to be dependent on the velocity ratio; the smaller the ratio, the more rapid the dilution increases. It also shows that no similarity on the radial concentration profiles can be found at different axial stations. The centreline dilution is anaylzed by computing the volume flux via the integration of the Chan-Lam equation of the velocity field. Separating the flow into a forward and a reverse flow, the analysis is further extended to model the whole concentration field. The analytical expression agrees reasonably well with the experimental results.