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Close-up of a still from a simulation produced during a study on lean, hydrogen-air mixtures showing a cutaway profile of the concentration of hydroxyl molecules (that are produced and consumed at the flame). Red areas mark regions of intense combustion; fine gray-blue vortex structures at the base of the flame mark turbulence.
Combustion produces over 80 percent of the nation's energy, but also a large percent of air pollutants. Robert Cheng and colleagues at Lawrence Berkeley National Laboratory developed a low-swirl burner for turbines and furnaces. Requiring no pilot light or moving parts, it is a nozzle fitted to the end of a fuel pipe. Inside the nozzle, airfoil-like vanes make the flow of fuel swirl and expand radially as it exits the pipe, creating a local stagnation region where a bowl-shaped flame can sit indefinitely. If enough swirl is added to hold the flame steady, while not trapping any hot combustion products in a recirculation above the flame, it can burn lean with ultralow emissions.Image credit: Lawrence Berkeley National Laboratory
