Vapor condensation in the mixing zone of a jet

Experimental studies were made of fog formation in free jets containing glycerine and dibutyl phthalate. Visual and photographic observations showed that condensation took place near the nozzle in the mixing zone between the jet and the ambient air. Fog formation began at a well‐defined location downstream from the nozzle depending on the initial velocity, temperature, and concentration of vapor. The location could be changed by inserting solid bodies or by adding foreign nuclei to the mixing zone. Measurements were made of mean temperature and concentration profiles in the mixing zone with noncondensable gases. These compared well with the predictions of turbulent boundary‐layer theory. Calculations were made of the supersaturation to be expected in the case of glycerine. Downstream of the point where condensation first occurred fog filled most of the region where the calculated supersaturation was above unity. Based on the experimental evidence a mechanism is proposed for condensation in a free jet.