Results 51 to 60 of about 404,526 (210)
Flight-Effects on Predicted Fan Fly-By Noise [PDF]
The impact on PNLT (Perceived Noise Level, Tone corrected) and Fly-by EPNL (Effective Perceived Noise Level) when forward motion reduces the noise generated by the bypass fan of an aircraft engine was studied.
Clark, B. J., Heidmann, M. F.
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Characteristics of an anechoic chamber for fan noise testing [PDF]
Acoustical and mechanical design features of NASA Lewis Research Center's engine fan noise facility are described. Acoustic evaluation of the chamber, which is lined with an array of stepped wedges, is described.
Essary, J. D. +2 more
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International Journal of Environmental Health Engineering, 2015 Aims: The main goal of this paper was to evaluate the effectiveness of Helmholtz resonator in noise reduction of duct equipped with active noise control (ANC). Materials and Methods: Noise frequency band was produced by a propeller fan, which was spread
Farhad Forouharmajd +3 more
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Reduction of fan noise in an anechoic chamber by reducing chamber wall induced inlet flow disturbances [PDF]
The difference between the flight and ground static noise of turbofan engines presents a significant problem in engine noise testing. The additional noise for static testing has been attributed to inlet flow disturbances or turbulence interacting with ...
Dittmar, J. H. +2 more
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Computer programs for handling propulsion system noise data [PDF]
, 1975 Computer programs have been developed for efficient handling of one-third-octave band noise data originating from outdoor full-scale fan noise facility and engine acoustic facility at Lewis Research ...
Montegani, F. J.
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Fluctuating pressures on fan blades of a turbofan engine, flight test investigation [PDF]
Miniature pressure transducers were used to measure the fluctuating pressure on the fan blades of a JT15D engine in flight to aid in understanding fan-noise generation.
Schoenster, J. A.
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Noise Test and Optimization of Auxiliary Converter for Metro Vehicle
机车电传动, 2018 In order to reduce the noise of auxiliary converter in metro vehicle, noise characteristics of the auxiliary converter were obtained through the vibration and noise test in different working conditions.
DING Jie +3 more
doaj
Вестник Самарского университета: Аэрокосмическая техника, технологии и машиностроение, 2018 A computational investigation of aerodynamic characteristics of a model ultrahigh-bypass ratio counter-rotating fan (m=20) developed at CIAM within the framework of the European Project COBRA (Innovative Counter Rotating Fan System for High Bypass Ratio ...
Ya. M. Druzhinin +2 more
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Preliminary design study of a quiet, high flow fan (QHF) stage [PDF]
Concepts selected to reduce fan generated noise in a turbofan are presented. Near-sonic flow at the fan inlet to reduce upstream propagated noise and the use of long-chord vanes to reduce downstream noise is discussed.
Beguhn, A. A. +4 more
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Two-stage, low noise advanced technology fan. 5: Acoustic final report [PDF]
The NASA Q2S(quiet two-stage) fan is a 0.836m (32.9 in.) diameter model of the STF 433 engine fan, selected in a 1972 study for an Advanced Technology Transport (ATT) airplane.
Riloff, N., Jr., Sofrin, T. G.
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