Mixing of Two Concentric Jets: Fid-Bau Portal

Mixing of Two Concentric Jets

Kotwal, D. C. / Reddy, Y. R. / Kar, Subir

A theoretical equation for estimating the mixing loss coefficient is given for mixing of two concentric jets. The equation has been experimentally verified with water as the working fluid. In the experiments, two outer nozzles of semicone angles of 12○ and 24○ were used for different velocity ratios varying from 0.00824 to 0.792. For an area ratio of 0.228 and main nozzle semicone angle of 12○ four nozzle distances of 2.4 cm, 3.4 cm, 4.4 cm, and 7.9 cm were tested. The mixing loss constant reduces with increase in velocity ratio to unity, beyond which it increases with increase in velocity ratio for a given area ratio and angle. The mixing loss constant increases with nozzle angle when all other parameters are constant. For a particular mixing configuration the mixing efficiency increases with nozzle distance and reaches an optimum value; with further increase of nozzle distance it decreases. An optimum efficiency for mixing of the order of 98% was obtained at a velocity ratio of 0.642 for a nozzle semicone angle of 24○ at a nozzle distance of 7.9 cm.