The roar of a rocket blasting off is the sound of raw power. In fact, the sound waves pack so much energy that if they throb with a certain pulsating beat, they can literally tear a rocket apart. The Pentagon and NASA have spent bundles to prevent this. But Ben T. Zinn, a professor of aerospace engineering at Georgia Institute of Technology, figured there ought to be a way to harness this power. His company, Sonotech Inc. in Atlanta, has developed a pulsed-combustion system that promises dramatic improvements in the performance of municipal incinerators. It should also reduce fuel consumption and emissions in big industrial furnaces.
Essentially, the Sonotech system is an overgrown trombone slide. It uses motorized baffles to adjust the dimensions inside a combustion chamber until it resonates with sound power. Properly tuned, a furnace's own roar fans the flames, adding energy to the combustion process and thus boosting its efficiency. In a test at an Environmental Protection Agency incinerator in North Carolina, EPA officials were also pleased by a 50% to 75% reduction in soot emissions. Sonotech is now outfitting a large cement-making furnace in Colorado owned by the big German cement company, Polysius.