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Exhaust resonators are also used to reduce potentially loud engine noise where the dimensions are calculated so that the waves reflected by the resonator help cancel out certain frequencies of sound in the exhaust. In some two-stroke engines, a Helmholtz resonator is used to remove the need for a reed valve.
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.
The propelling nozzle converts a gas turbine or gas generator into a jet engine. Power available in the gas turbine exhaust is converted into a high speed propelling jet by the nozzle. The power is defined by typical gauge pressure and temperature values for a turbojet of 20 psi (140 kPa) and 1,000 °F (538 °C). [18]
The most-cited advantages of the turbine engine, according to the participants' interviews, were its smooth and vibration-free operation, reduced maintenance requirements, and ease of starting in different conditions; the most-common complaints concerned its slow acceleration, sub-par fuel economy, and relatively high noise level.
Steam turbines and gas turbines, on the other hand, when new and/or in good repair, do not, by themselves generate excessive vibration as long as the turbine blades are in a perfect condition and rotate in a smooth gas flow. But after some time microscopic defects appear and cause small pits to appear in the surface of the intake and the blades ...
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The PW 300 series has been developed in partnership with MTU who are responsible for the low pressure turbine. The first variant, the PW305A, has the following configuration and was designed with a core flexible enough for engines with take-off thrusts from 20 kN to 31 kN (4,500 to 7,000 lb): a single-stage fan driven by a three-stage low pressure turbine, supercharging a four-stage axial ...
Robins are a much loved Christmas icon, but wind turbines installed in their habitat are affecting their song, with worrying consequences. Robin hushed: wind turbines are making songbirds change ...