Surface Dilution of Round Negative Buoyant Jets–A Comparison with Other Jets

Abstract

Experimental results, concerning surface dilutions of round turbulent jets with negative buoyancy, are presented and discussed. Fresh water jets, of density ρo, discharging from a vertical pipe, of internal diameter do, placed in the middle of the experimental tank, at a depth H from the free surface of a quiescent ambient liquid, consisting of common salt water solution, of density ρs, slightly larger than ρo, have been studied. Dilution measurements, made with a conductivity probe, have been performed, along radial traverses, at a small depth of 5do, below the free surface. The experimental results were analyzed and presented in terms of dimensionless dilution scale gl versus the dimensionless length scale zl. In this form they are directly compared to axial dilution results of the positive buoyant jet. With the proper definition of length scale, they are expressed satisfactorily by the well established semiem-pirical expressions, concerning the axial dilution of positive buoyant jets. Semiem-pirical relationships, concerning the axial dilution distribution of the horizontal buoyant jet, are also presented. Thus, a direct comparison is made possible for surface dilutions in the three round buoyant jet cases, namely the positive, the negative and the horizontal jet, which will be very useful in engineering design.