A Method to Further Reduce the Perceived Noise of Low Tip Speed Fans
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Page : 28 pages
File Size : 38,25 MB
Release : 2000
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Author :
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Page : 28 pages
File Size : 38,25 MB
Release : 2000
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Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
Page : 38 pages
File Size : 47,6 MB
Release : 2018-06-16
Category :
ISBN : 9781721236114
The use of low tip speed, high bypass ratio fans is a method for reducing the noise of turbofan jet engines. These fans typically have a low number of rotor blades and a number of stator vanes sufficient to achieve cut-off of the blade passing tone. Their perceived noise levels are typically dominated by broadband noise caused by the rotor wake turbulence - stator interaction mechanism. A 106 bladed, 1100 ft/sec takeoff tip speed fan, the Alternative Low Noise Fan, has been tested and shown to have reduced broadband noise. This reduced noise is believed to be the result of the high rotor blade number. Although this fan with 106 blades would not be practical with materials as they exist today, a fan with 50 or so blades could be practically realized. A noise estimate has indicated that such a 50 bladed, low tip speed fan could be 2 to 3 EPNdB quieter than an 18 bladed fan. If achieved, this level of noise reduction would be significant and points to the use of a high blade number, low tip speed fan as a possible configuration for reduced fan noise. Dittmar, James H. Glenn Research Center NASA/TM-2000-210457, E-12453, NAS 1.15:210457
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Page : 492 pages
File Size : 50,94 MB
Release : 1994
Category : Aeronautics
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Page : 124 pages
File Size : 49,65 MB
Release : 1973
Category : Airplanes
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Page : 700 pages
File Size : 37,8 MB
Release : 1975
Category : Aeronautics
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Author :
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Page : 518 pages
File Size : 24,5 MB
Release : 1993
Category : Aeronautics
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Page : 880 pages
File Size : 17,72 MB
Release : 1976
Category : Aeronautics
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Author : Colin H. Hansen
Publisher : John Wiley & Sons
Page : 628 pages
File Size : 11,49 MB
Release : 2017-04-17
Category : Technology & Engineering
ISBN : 111882606X
A comprehensive guide to wind farm noise prediction, measurement, assessment, control and effects on people Wind Farm Noise covers all aspects associated with the generation, measurement, propagation, regulation and adverse health effects of noise produced by large horizontal-axis wind turbines of the type used in wind farms. The book begins with a brief history of wind turbine development and the regulation of their noise at sensitive receivers. Also included is an introductory chapter on the fundamentals of acoustics relevant to wind turbine noise so that readers are well prepared for understanding later chapters on noise measurements, noise generation mechanisms, noise propagation modelling and the assessment of the noise at surrounding residences. Key features: Potential adverse health effects of wind farm noise are discussed in an objective way. Means for calculating the noise at residences due to a wind farm prior to construction are covered in detail along with uncertainty estimates. The effects of meteorological conditions and other influences, such as obstacles, ground cover and atmospheric absorption, on noise levels at residences are explained. Quantities that should be measured as well as how to best measure them in order to properly characterise wind farm noise are discussed in detail. Noise generation mechanisms and possible means for their control are discussed as well as aspects of wind farm noise that still require further research to be properly understood. The book provides comprehensive coverage of the topic, containing both introductory and advanced level material.
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Page : 1098 pages
File Size : 19,62 MB
Release : 1982
Category : Power resources
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Author : Jet Aircraft Noise Panel (U.S.)
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Page : 172 pages
File Size : 48,73 MB
Release : 1966
Category : Airport noise
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