Another application involves hydrogen-burning engines, which may be used in the future for cars and other devices. Inside the module, a laminar jet flame will be produced by igniting a stream of gaseous hydrocarbon fuel coming out of a nozzle. A laminar flame is steady, like an unflickering candle flame, as opposed to turbulent, like a campfire, which flickers and has unpredictable flow patterns. Laminar flows, which are best produced in microgravity due to the lack of buoyancy forces, are more easily modeled by scientists, making them the preferred means of testing theories of combustion. In this case, Faeth is looking at theories concerning the production of soot.
Soot is usually an undesirable product of combustion for several reasons.
Another of soot's undesirable qualities is that the thermal radiation, or heat emission, of soot particles is often responsible for the spreading of fires. Soot also hampers efforts to fight fires because its presence can obscure their sources, making it more difficult to extinguish them. However, soot production is useful to the carbon black industry, which is a large industry that uses soot in such products as tires, black plastic, and dry-cell batteries. In addition, many furnace applications rely heavily on heat radiation from soot to transfer heat from flames to boiler tubes in order to produce steam from water. For all of these reasons, understanding the production of soot is a goal that is important to researchers.