Effect of high wind speeds on droplet formation in sprays

We investigate the effect of high wind speeds on the breakup mechanisms that govern the formation of a spray from nozzles that form liquid sheets, which subsequently break up. The fragmentation mechanism of liquid sheets from spray nozzles has recently been described in detail under quiescent condit...

Full description

Saved in:
Bibliographic Details
Published in:Journal of fluid mechanics 2024-12, Vol.1000
Main Authors: Varkevisser, Thijs, Kooij, Stefan, Villermaux, Emmanuel, Bonn, Daniel
Format: Article
Language:English
Subjects:
Air flow
Breakup
Droplets
Hydraulics
JFM Papers
Lasers
Liquid sheets
Nozzles
Pesticides
Predictions
Probability density functions
Size distribution
Spray nozzles
Sprays
Taylor instability
Velocity
Wavelengths
Wind effects
Wind measurement
Wind speed
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We investigate the effect of high wind speeds on the breakup mechanisms that govern the formation of a spray from nozzles that form liquid sheets, which subsequently break up. The fragmentation mechanism of liquid sheets from spray nozzles has recently been described in detail under quiescent conditions. With high wind speeds, measurements of the droplet size distribution reveal two rather than one characteristic drop sizes, suggesting the existence of two distinct breakup mechanisms. High-speed images of the spray are used to identify these two mechanisms. We show that the smaller droplets result from the breakup of ‘bags’ formed in the spray sheet by the wind, while the larger droplets result from the breakup of the remaining perforated sheet. Based on the two mechanisms, a probability density function is constructed and fitted to the measured droplet size distributions. We show that the spray sheet destabilises due to the Rayleigh–Taylor instability induced by the airflow, and that the experimentally observable breakup length and size of the holes blown in the sheet are predicted by the fastest growing wavenumber. From this, a theoretical prediction for the droplet size from bag breakup and remaining sheet breakup is derived.
ISSN:0022-1120
1469-7645
DOI:10.1017/jfm.2024.1042