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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.
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.
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 ...
Discourse analysis (DA), or discourse studies, is an approach to the analysis of written, spoken, or sign language, including any significant semiotic event. [ citation needed ] The objects of discourse analysis ( discourse , writing, conversation, communicative event ) are variously defined in terms of coherent sequences of sentences ...
Noise pollution, or sound pollution, is the propagation of noise or sound with potential harmful effects on humans and animals. The source of outdoor noise worldwide is mainly caused by machines, transport and propagation systems.
Aeroacoustics is important to understanding how wind musical instruments work. [2] Architectural acoustics – science of how to achieve a good sound within a building. [3] It typically involves the study of speech intelligibility, speech privacy and music quality in the built environment. [4] Also known as building acoustics.
Aeroacoustics is a branch of acoustics that studies noise generation via either turbulent fluid motion or aerodynamic forces interacting with surfaces. Noise generation can also be associated with periodically varying flows. A notable example of this phenomenon is the Aeolian tones produced by wind blowing over fixed objects.
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.