Density Effects on Dilution and Height of Vertical Fountains

Abstract

The effects of relative density difference on the dilution and height of vertical negative buoyant jets were investigated experimentally. These effects, which are related to fluid density, occurred in addition to the buoyancy effects commonly parameterized by the densimetric Froude number. The density effects have generally been ignored in previous investigations and in practice on the basis of Boussinesq’s approximation. The density effects could, however, be relevant in connection to hypersaline discharges from desalination plants and dense discharges from oil and potash mining industries. A series of seven upward fountain experiments were performed in the laboratory to carry out this investigation. The flow was turbulent, the relative density difference varied from 0.0014 to 0.064, and the densimetric Froude number varied from 2.13 to 15.7. The results showed that an increase in the relative density difference reduced both the minimum return dilution and maximum height of the fountains. The observed maximum reduction in dilution was 48%, and the maximum reduction of height was 19%. The results also demonstrated that upward fountains are dynamically similar to downward fountains.