QUT researchers have advanced the understanding of how to create tiny seawater droplets to form mist plumes that reflect sunlight to protect coral reefs.
- Improved understanding of how sun-reflecting mist technology works
- Modelling in high resolution reveals how high-pressure spray system splits seawater droplets
- Offers new insights to optimise seawater fogging technology to shield coral from bleaching
The researchers, from QUT's School of Earth and Atmospheric Sciences and from Southern Cross University's National Marine Science Centre, focused on 'secondary droplet break up' a process in which already formed droplets continue to fragment into smaller ones.
First author, PhD researcher Saima Bukhat Khan said this new finding could lead to improvements in the high-pressure spray systems that the RRAP Cooling and Shading team is using to create a dense mist of sea spray capable of shielding high-priority reefs during days of sweltering calm weather that bring the greatest risk of coral bleaching.
"Our findings provide a deeper understanding of how these fine droplets, form, move, and change in size after being sprayed," Ms Khan said.
"We used a combination of wind tunnel experiments and computer modelling to analyse how filtered seawater droplets behave when sprayed through special nozzles called 'impaction-pin' nozzles.
"These experiments and computer simulations enabled us to model the droplet sizes and spray patterns with high accuracy."
Ms Khan said the team found that the spray produced a wide and even mist of droplets at sizes consistent across experiments and simulations.
"This type of detail leads the way to better design of nozzles and spraying systems for environmental applications."
Co-researcher QUT Dr Joel Alroe said the findings could be applicable to more than coral protection.
"Spray technologies are used in agriculture, medicine and industrial settings," Dr Alroe said.
"The more we understand about droplet dynamics, the more efficient and precise systems we can design."
The research team comprised Ms Khan, Dr Joel Alroe, Professor Zoran Ristovski from QUT's School of Earth and Atmospheric Sciences; Professor Emilie Sauret, from QUT's School of Mechanical, Medical and Process Engineering; and Dr Chris Medcraft and Associate Professor Daniel Harrison from the National Marine Science Centre, Southern Cross University.
The research is part of the Reef Restoration and Adaptation Program, funded by the partnership between the Australian Government's Reef Trust and the Great Barrier Reef Foundation.
The study, Secondary droplet breakup of impaction-pin nozzle: Comparison between experimental and CFD-DPM modelling, was published in the Journal of Aerosol Science.
Main image, from left Saima Khan, Dr Joel Alroe, Professor Zoran Ristovski.
