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Noise-generating aircraft propeller. Aircraft noise is noise pollution produced by an aircraft or its components, whether on the ground while parked such as auxiliary power units, while taxiing, on run-up from propeller and jet exhaust, during takeoff, underneath and lateral to departure and arrival paths, over-flying while en route, or during landing.
This gives a less effective exhaust gas velocity (lower jet noise) and therefore lower efficiency, and can be achieved in the landing phase by using a variable area final nozzle to rematch the fan. Furthermore, acoustic treatment in the intake and exhaust ducting can minimize turbomachinery noise.
The FAA Stage 5 noise standards are equivalent. [49] Higher bypass ratio engines produce less noise. The PW1000G is presented as 75% quieter than previous engines. [50] Serrated edges or 'chevrons' on the back of the nacelle reduce noise. [51] A Continuous Descent Approach (CDA) is quieter as less noise is produced while the engines are near ...
Acoustic sources within the "jet pipe" also contribute to the noise, mainly at lower speeds, which include combustion noise, and sounds produced by interactions of a turbulent stream with fans, compressors, and turbine systems. [1] The jet mixing sound is created by the turbulent mixing of a jet with the ambient fluid, in most cases, air.
In the US, the Concorde noise was measured at DFW and Dulles airports: [17] Based on the data given in Tables 11 and 12, it appears that the approach noise of the Concorde is somewhat higher than that for present day commercial aircraft. The takeoff noise is, for locations close the airport, considerably higher than present aircraft.
Canestrino also reported that noise levels are up from last year, with a monitor affixed near the top of the hospital averaging noise data of 62.6 decibels in May 2024, compared to 59.5 decibels ...
Steve Angeli replaced Leonard with the Irish trailing 10-0. Leonard’s exit came as Notre Dame offensive lineman Rocco Spindler was treated by training staff.
Highway noise is today less affected by motor type, since the effects in higher speed are aerodynamic and tire noise related. Other contributions to the reduction of noise at the source are: improved tire tread designs for trucks in the 1970s, better shielding of diesel stacks in the 1980s, and local vehicle regulation of unmuffled vehicles. [13]