Scientists use spherical flames on ISS to understand fires without soot

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The fires aboard the International Space Station (ISS) are a very bad thing if they are not part of an experience that allows you to unravel the most fundamental mysteries of the natural world. Scientists do not really know why some fires produce soot and some do not. The unique nature of microgravity on the ISS allowed the crew to create spherical flames to clear up the problem.

Of course, you can create sooty flames by changing the composition of your fuel. Oxygen is of course necessary for combustion. The air on Earth also contains nitrogen. The nitrogen is inert, but by removing nitrogen from the air and adding it to the fuel, you can create a flame without soot. But why?

There are two opposing views on the mechanism at work here. Scientists think on the one hand that it is the change in the flow of gas in the fire that captures the carbon that would form the soot. Others say that the movement of nitrogen from the air to the fuel changes the temperature of the fire and that the variation of temperature and shape through the flame prevents the formation of soot.

To get out of the stalemate, scientists must accurately control the flow of gas in the flame. On Earth, the gases always flow upwards, giving the flames this characteristic elongated shape. On the ISS, the flames do not extend and you can control the flow of gas.

So, on the International Space Station, researchers ignited small fires that were naturally completely spherical. These flames have no yellow component, sign of impurities such as soot.

By using the flames of the International Space Station, scientists can determine which proposal is the right one. If the theory of gas flow is right, the spherical flames in space will produce soot. If it depends on temperature and structural variations, there will be no soot. Astronauts will be able to measure the strength and longevity of the flames. They expect the flames of the ISS to be stronger than those of the Earth, with a mixture of nitrogen and oxygen in the air.

This research, which is still ongoing, could help clarify some of the fundamental areas of the science of combustion. Even if humans have been lighting fires since the beginnings of human civilization, we may have to go into space to understand how fires work.

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