This approach will allow them to effectively design both the engine and nozzles for the optimum airflow to reduce sound output. Now, engineers are combining computational fluid dynamics to accurately depict the physics of turbulence and remove some of their guesswork. Engineers experiment with all sorts of shapes and patterns in the designs of exhaust nozzles to manage the air as it vacates the craft. Therefore, many jet plane alterations combine trial and error to achieve the right balance. There is much that physicists still do not understand about the chaotic nature of air turbulence. This is because the high-velocity air from the engine meets with the relatively still air surrounding the plane. In addition, jet planes seem to be at their loudest when they're traveling slow, that is, during take-off and landing. The chevrons help to smooth the mixing of hot air from the engine core and colder air flowing through the engine, which lessens turbulence and noise. Chevrons on jet engines are the sawtooth pattern found on some jet engine nozzles' trailing edges. Still, it's a compromise that engineers must balance when reducing harmful noise.Īnother method of minimizing jet engine noise is to use chevron nozzles. A mixer helps to decrease the gas's temperatures and, in turn, its velocity, which can (and often does) impact the jet's performance. Therefore manufacturers have to find ways to curtail some of the sounds, which often involves them fixing a hush kit or mixer to the engine's end.Ī mixer works to combine the hot exhaust gas with cold air. How Can Jet Engine Noise Be Reduced?Ī jet engine's high decibel noise can seriously harm our hearing. Prolonged exposure damages the hearing and can lead to several other health issues. Jet engine noise is a problem for those who have to live and work around these aircraft. The study concluded that even with protective devices, the group exposed to the continuous noise of jet engines had poorer hearing than those without exposure. This research aimed to assess hearing damage over prolonged exposure to jet engine noise. Continuous high-decibel noise can lead to memory impairment, stress, and in some cases, conditions such as heart disease.Īnd these high SPLs (sound pressure levels) can be particularly detrimental to those working near the aircraft.Ī study took 60 men, aged between 24 and 50, who work as technical staff regularly exposed to jet engine noise and compared them with 50 males, aged between 25 and 51, who had no previous exposure to the harsh sounds of a jet engine. Jet engine noise can be a problem for people living close to airports. This cycle continues as the engine's fan rotates at 4000 rpm, creating incredibly high-frequency oscillations. Air entering the engine through the fan and fiery air blasting through the nozzle create significant turbulence in the surrounding air, creating a bunch of pressure waves. In simple terms, a sound is a pressure wave that travels through a medium like air. Jet noise is most noticeable during take-offs and landings. This process creates a powerful noise by creating turbulence in the surrounding air. That means the jet is pushed in the opposite direction, thus powering the plane. Instead, it must make its way out through a nozzle at the opposite end of the engine.Īccording to Newton's third law, this reaction creates an equal and opposite force. It cannot go back the way it came due to the pressure of the incoming air.
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