Do you know what are chevrons and what purpose do they serve? The wavy teeth pattern that can be seen on the rear end of the jet engines are called chevrons. According to Jim Banke, NASA Aeronautics Research Mission Directorate, ‘the saw-tooth pattern seen on the trailing edges of some jet engine nozzles. As hot air from the engine core mixes with cooler air blowing through the engine fan, the shaped edges serve to smooth the mixing, which reduces turbulence that creates noise.’
The noise produced by aircraft during the landing and take-off has always been a pressing matter for those who reside near the airports. The persistent airport community protest, environmentalists’ cries, and the strict International Civil Aviation Organization (ICAO) standards for controlling the noise pollution has forced the hand of government and manufactures for coming up with unique and feasible solutions that can help save the people from the negative effects of engine noise around and at the airports.
The pure jet engines that were utilized in fifty to sixty years old technology for fighter aircraft were by far the noisiest jets. The modern jets make use of low bypass jet engines that are not only more fuel efficient but also quite less noisy as compared to their predecessors. The increase in bypass ratio of jet engines that are used in large commercial aircraft has not only improved the fuel consumption but also helped with cutting the noise down.
In a large bypass engine, the bigger part of air doesn’t pass through the engine but rather flows around it. This air mass is cooler and mixes violently with exhaust gases that are coming out from the engine core; this causes high-turbulent which is the source of the noise. The chevron technology enables the smoother mixing of exhaust gases with the cooler masses of air thus reducing the noise.
Chevron technology was developed by NASA in 2010 and is being used by engine manufacturers as well.