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Self-charging of sprays.
Stefan Kooij1, Cees van Rijn2, Neil Ribe3
1Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, Amsterdam, The Netherlands. s.a.kooij@uva.nl.
Scientific Reports
|November 12, 2022
Summary
Liquid charging in laminar jets is quantified, revealing a simple model that explains streaming currents across various parameters. This research offers insights into controlling spray characteristics by manipulating nozzle coatings.
Area of Science:
- Fluid dynamics
- Electrostatics
- Surface science
Background:
- Liquid charging during flow is a known phenomenon but not fully understood.
- Droplet charging significantly impacts spray plume dynamics and travel distance.
- Existing models and scaling laws are complex due to numerous influencing factors.
Purpose of the Study:
- To quantify liquid charging in laminar jets generated by ultra-short channels.
- To develop a simple model explaining charging as a function of key parameters.
- To investigate methods for controlling charging polarity.
Main Methods:
- Focusing on laminar jets in ultra-short channels as a simplified flow regime.
- Systematically varying nozzle size, flow velocity, and surface treatments.
- Measuring streaming currents to quantify charging levels.
Main Results:
- A simple model was developed that successfully collapses data across four orders of magnitude in streaming currents.
- The model accounts for variations due to nozzle size, flow velocity, and surface treatments.
- Reversing charging polarity was achieved by applying oppositely charged nozzle coatings.
Conclusions:
- A unified model explains liquid charging in laminar jets across diverse conditions.
- Controlling charging polarity via nozzle coatings is feasible, offering application potential.
- This work provides a foundational understanding for manipulating spray behavior through electrostatic charging.
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