Two-phase velocity measurement in a particle-laden jet

A horizontally discharging jet laden with solid sediment particles is investigated experimentally. The submerged jet discharges water with an initially horizontal direction into stagnant water of the same density but the presence of sediment particles produces jet effluent having a combined density greater than that of the ambient water. A modified particle-imaging velocimetry (PIV) technique is applied to estimate the velocity fields of the solid particle phase and the jet fluid liquid phase. Phase separation is achieved optically between the scattered light signals from the particles and the laser-induced fluorescence signal from the jet fluid dozed with a fluorescent dye. It is found that initial sediment concentrations below 0.1% volume fraction do not cause significant changes to the global properties of the jet flow. In jets of higher initial sediment concentrations, settling of sand particles are observed to drag the jet to spread with a downward-bending mean trajectory. Intensive particle–flow interaction is also observed in jets of high sediment concentrations.

► A modified particle-imaging velocimetry (PIV) technique is applied to measure the velocity fields of solid particle phase and jet fluid liquid phase of particle-laden jets.
► Optical phase separation is achieved by difference in wavelength between laser light scattered by sediment particles and fluorescence light emitted by dye-containing jet fluid.
► Sediment particles of initial concentration not higher than 0.1% in volume fraction do not lead to significant modification of global properties of the jet.
► A jet laden with a higher particle concentration is found to have its jet centerline trajectory bent downwards by the sediment load.