4D Flow field measurements of air-entrained turbulent impinging water jets onto a quiescent water surface

This paper presents a time-resolved three-dimensional flow field measurement of the continuous phase of a turbulent impinging jet using Lagrangian particle tracking velocimetry utilizing the Shake-The-Box algorithm. Time-series images of fluid tracer particles were acquired using systems equipped with four high-speed cameras. The Vortex-in-cell sharp method was used to reconstruct the Eulerian flow fields of the particle tracks. The impinging jet was characterized as plume-like along the vertical direction with two distinct layers: developing shear (recirculation zone) and fully developed shear. The buoyant bubbles influenced the streamwise vortex structures of the continuous phase. The results revealed high amplitude oscillations of acceleration and deceleration near the jet source, forming ring-like vortices that break down as the jet moves downstream with its momentum dissipated. The flow of the continuous phase of the impinging jet was self-similar at the developed shear layer and fully developed diffusion layer beneath the water pool and was characterized as homogeneous shear flow with anisotropy turbulence.