A Novel Method for Eliminating Mach Waves in Supersonic Jets
Aircraft designers face the technological challenge of reducing the noise produced by supersonic aircraft exhausts. These exhausts, if left untreated, produce environmentally unacceptable levels of noise. Much of this noise is due to Mach waves, the shock waves attached to turbulent eddies moving at supersonic velocities.Researchers have attempted to eliminate much of the noise associated with supersonic engines by minimizing the Mach waves produced in the engines' exhaust.
Currently, only two devices have shown much promise in suppressing supersonic jet Mach waves. Lobe mixers, the more prominent device, effect suppression by mixing jet gas with slower-moving surrounding air. The mixed jet gas decelerates quickly and, thus, produces fewer, but potentially stronger, Mach waves. Lobe mixers are not widely favored because they produce a considerable loss of thrust and limit aircraft fuel efficiency. The ejector shroud, the less prominent Mach wave-suppressing device, acts basically as a muffler. Ejector shrouds are only effective at very low flight speeds and their use results in severe weight and aircraft performance penalties. Technology: A researcher at the University of California has devised a method for the elimination of Mach waves that does not suffer from the limitations seen in the currently available devices. Unlike the other less successful devices, this method minimizes Mach waves not by attempting to suppress or "muffle" them but, rather, by preventing their formation via alteration of the turbulent-eddy dynamics. Application: ADVANTAGES:
- This method prevents formation of Mach waves in supersonic jet exhausts. - Various configurations may selectively suppress sideline, take-off, or unidirectional noise. - This method shouldn't cause thrust losses if incorporated into a suitably designed engine. - Implementation of this method in a suitably designed engine should impose only minimal weight and performance penalties
Patents:
US 5,590,520
Type of Offer: Licensing
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