AbstractThis paper deals with the experimental study of mixing characteristics by means of steady and unsteady jets. Investigations were carried out with one and two steady jets, and with two alternate intermittent jets, supplying 0.1 m3and 70 m3tanks. From the data obtained from several sensors put into the tank, the signification of the mixing time as applied to the tank is discussed. A Reech‐Froude similarity appears to be a good way in scaling the results obtained on either 0.1 m3or 70 m3models. Combining the specific momentum of the jets and the tank characteristics, a mixing time factorMis deduced which permits the evaluation of the mixing time. The efficiency of different configurations of jets are then compared through a degree of transient inhomogeneity and required powe