Numerical simulation and instability analysis of particles in liquid–solid concave‐wall jet using DPM‐RSM

Abstract

The liquid–solid concave‐wall jet existed in the vertical cylinder separator with tangential inlet; the instability near concave‐wall was the key factor for centrifugal separation. The effects of jet flowrate and wall curvature radius on the instability of solid‐particles were explored by experiment and numerical simulation. The results showed that the separation efficiency of particles decreased with the increase of centrifugal separation factor. The liquid–solid concave‐wall jet flow in separator was unstable in this study. The decay rate of jet maximum velocity on the concave‐wall was larger than that on plane‐wall jet. The ratio of half‐width value to wall curvature radius was about 0.08 at the circumferential direction 90°, which coincided with the critical value of centrifugal instability in strongly concave‐wall jet. The pressure, velocity, and vorticity fluctuated periodically along streamwise direction in separator. The fluctuation period was linearly related to the wall curvature, and the radial range of fluctuation was only half of jet width. The paired longitudinal vortices formed along the flow direction, and the longitudinal vortices merged at length 0.74 m from the inlet cross‐section along circumferential direction. After the position of vortices merged, the particle trajectory oscillated obviously.

Effect of the Curvature Radius on Single-Droplet Dynamic Characteristics within a Concave-Wall Jet

“…Our previous research found that wall jet flow was affected by the curvature radius of a concave wall in two ways: the jet spread in the radial direction shrank and the instability at the jet boundary increased [27]. Within the potential studies on concave-wall jets, the intrinsic and extrinsic factors of droplet deformation were of particular interest to this paper.…”

“…Ouyang et al revealed the breakup mechanism of fluid particles in turbulent flows based on the LES-VOF model, where droplets obtained more energy from the turbulent vortices into the breakup when the interfacial energy reached a critical value [26]. Zhang et al used the LES-VOF model to describe the droplet deformation and breakup caused by vortices [27]. The above studies indicated that the LES-VOF model is recognized as a classic method to explain droplet dynamic characteristics.…”

Effect of Curvature Radius on Single Droplet Dynamic Characteristic within Concave-Wall Jet

“…Our previous research found that the wall jet flow was affected by the curvature radius of concave-wall in two ways, the jet spread in radial direction shrank [27] and the instability at the jet boundary increased [28]. Within the possible studies in concave-wall jet, the intrinsic and extrinsic factors of droplet deformation were the particular interest to this paper.…”