Air-water-sand three-phase jets in crossflow, Part II: Velocity distributions and turbulence characteristics of bubbles and sand particles

This study examines the velocity and turbulence characteristics of bubbles and sand particles in air-water-sand three-phase jets in crossflow, building upon the phase concentration analysis presented in Part I. Bubble Image Velocimetry (BIV) and Particle Tracking Velocimetry (PTV) were employed to quantify these parameters under varying initial jet conditions, including different sand concentrations, slurry (water-sand) flow rates, and air flow rates. The presence of negatively buoyant sand particles reduced peak bubble rising velocities by up to 15 %, while simultaneously enhancing bubble turbulence intensities by approximately 15 %. Slurry flow rate exhibited a pronounced effect, increasing peak bubble rising velocities by 70 % and sand vertical velocities by 88 %. Higher slurry flow rates also delay the development of streamwise bubble velocity along the jet trajectory and promote a more uniform distribution of bubble turbulence intensity. The transition height of sand particles—from rising to settling—decreased with increasing initial sand concentration but increased with higher slurry flow rates. A predictive model was developed to characterize this transition, demonstrating strong agreement with experimental data (R 2 = 0.97). The turbulence intensity of sand particles peaked near the upstream shear layer and sharply decreased in the settling region, reflecting a steady deposition process. • Velocity and turbulence of bubbles and sand particles were revealed. • Sand particles reduced bubble rising velocity but enhanced bubble turbulence. • Increased slurry flow rate elevated both bubble and sand vertical velocities. • A predictive model was developed for sand transition from rising to settling. • Sand turbulence intensity dropped rapidly from the rising to the settling region.