Discrete burning

This hypnotic video was recorded during a parabolic flight experiment on board the Falcon-20 aircraft of the Canadian National Research Centre that offers researchers up to eighteen seconds of precious zero-gravity.

It shows at 30 times reduced speed iron metal dust igniting as it reaches combustion heat in slow-motion. So-called discrete burning occurs when a piece of fuel ignites and burns completely due to the heat created by other fuel elements around it. Unlike traditional fires that burn through their fuel continuously, discrete fires spread by jumping from one fuel source to another. There are very few examples of discrete fires on Earth, but sparklers commonly used on New Year’s Eve burn are an example. Another example is forest fires, where trees burn individually and the next tree burns only when the heat from burning trees around it reaches the temperature necessary for combustion.

Metals have high energy density but they do not ignite easily unless in powder form, when they burn in discrete flames. By setting the metal powder alight in microgravity researchers can study how it burns in a chamber with evenly spaced metal powder suspended in weightlessness. This is not possible in a normal laboratory on Earth as powder clumps together into a pile due to gravity.

The results from the burning will be analysed to create models of discrete burning to extrapolate the ideal conditions of particles’ flow and Oxygen concentration.

Once researchers know what the ideal mixture is, we can work towards creating it in a power station, or, possibly, in a car’s engine; by injecting the iron powder into a chamber for a brief moment it could be engineered to have the perfect conditions for combustion.

The beauty of metal combustion is that it is carbon-free, if one burns iron powder for example the only ‘waste’ product is rust.

This video is part of the PERWAVES series of experiments run by ESA and has been conceived and designed by the McGill University in Montreal and an Airbus team in Bremen, Germany.

Watch and download the full video here: https://www.esa.int/ESA_Multimedia/Videos/2019/11/Discrete_burning