A new product, chevron nozzle, has been developed for turning down the whine of airplane by several notches. The chevron nozzles create vortices in the sheet and they mix the two flow streams together more rapidly. The serrated teeth of the nozzle make the shear layer disappear. The idea of mixing jet exhaust for the purpose of noise reduction first appeared in the 1980s, when the US Air Force started looking for ways to reduce fighters' infrared signature. By making the angle smaller by which the chevrons penetrate the exhaust stream, a low-frequency noise reduction can be obtained without the high-frequency penalty. Using shape memory alloys, the chevrons will be able to bend in and out of the flow exactly as needed. Activated by temperature, the tabs can be told when to change shape based on the atmospheric conditions at take off and cruise altitude.
Put a nozzle on it
Mechanical Engineering ; 128 , 11 ; 38-39
2006
2 Seiten
Aufsatz (Zeitschrift)
Englisch