Influence of jet exit conditions on the passive scaler field of an axisymmetric free jet

The influence of initial flow conditions on the passive scalar field of a t urbulent free jet issuing from the round nozzle is investigated in this pap er by a review of the literature and a detailed experimental study. Two set s of distinctly different initial conditions are generated using two nozzle types: a smooth contraction and a long straight pipe. The present measurem ents of the passive scalar (temperature) field were conducted in a slightly healed air jet from each nozzle at a Reynolds number of 16000 using identi cal experimental facilities and a single measurement technique. Significant differences between the flows from the two nozzles are revealed throughout the measured flow region which covers the axial range from 0 to 70 jet exi t diameters. The study suggests that the differences observed in the statis tics of the scalar held may be related to differences in the underlying tur bulence structure of the jet in the near field. The present findings suppor t the analytical result of George (1989) that the entire how is influenced by the initial conditions, resulting in a variety of self-similar states in the far field.