Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

On Free Moving Micron-Sized Droplet-Particle Collisions

Tushar Srivastava, Karrar H. Al-Dirawi, Benjamin Lobel, Andrew E. Bayly

Abstract

Predictive modelling of agglomeration in spray drying and particle capture in aerosol scavenging requires a fundamental understanding of droplet-particle collisions. The study complements prior work by investigating mid-air collisions between free micron-sized spherical droplets and particles with a size ratio of three. Particle wettability and density are varied to elucidate the mechanisms governing collision outcomes and the role of collision offset. Results show that particle density determines whether a particle is engulfed by the droplet or remains at the droplet interface during capture, while high wettability suppresses particle separation even in glancing collisions. A modified effective Weber number incorporating particle density and wettability is proposed to map collision outcomes. To assess its robustness, the present data are combined with literature results in a unified regime map. The regime boundaries separating collision outcomes collapse when the size ratio and Ohnesorge number are held constant. However, at a given collision offset, variations in size ratio and Ohnesorge number alter the critical effective Weber number for particle separation through changes in collision geometry and viscous resistance.

On Free Moving Micron-Sized Droplet-Particle Collisions

Abstract

Predictive modelling of agglomeration in spray drying and particle capture in aerosol scavenging requires a fundamental understanding of droplet-particle collisions. The study complements prior work by investigating mid-air collisions between free micron-sized spherical droplets and particles with a size ratio of three. Particle wettability and density are varied to elucidate the mechanisms governing collision outcomes and the role of collision offset. Results show that particle density determines whether a particle is engulfed by the droplet or remains at the droplet interface during capture, while high wettability suppresses particle separation even in glancing collisions. A modified effective Weber number incorporating particle density and wettability is proposed to map collision outcomes. To assess its robustness, the present data are combined with literature results in a unified regime map. The regime boundaries separating collision outcomes collapse when the size ratio and Ohnesorge number are held constant. However, at a given collision offset, variations in size ratio and Ohnesorge number alter the critical effective Weber number for particle separation through changes in collision geometry and viscous resistance.
Paper Structure (6 sections, 8 equations, 6 figures, 1 table)

This paper contains 6 sections, 8 equations, 6 figures, 1 table.

Table of Contents

  1. Introduction
  2. Methodology
  3. Result & Discussions
  4. Conclusions
  5. Acknowledgements
  6. References

Figures (6)

  • Figure 1: Schematic of the experimental setup employed in the present study
  • Figure 2: Schematic representation of the collision offset as observed from front and side camera
  • Figure 3: Time resolved snapshots showing D-P interactions for all three particles: GB, TGB, and PB at $We_d\approx67$ and $B\approx0.1$.
  • Figure 4: Time resolved snapshots showing D-P interactions for all three particles: GB, TGB, and PB at $We_d \approx 65$ and $B=0.7$.
  • Figure 5: Plots showing coalescence (black symbols) and separation (red symbols) outcomes for beads: Glass beads (GB), Polyethylene beads (PB), and Treated Glass beads (TGB), colliding with water droplet at different $We_p$ and $B$ with size ratio, $\Delta=3$.
  • ...and 1 more figures