scholarly journals Community Noise Impact from Military Helicopter Operations

1973 ◽  
Vol 54 (1) ◽  
pp. 342-342
Author(s):  
Jeffrey Goldstein ◽  
Roger Heymann ◽  
Clifford R. Bragdon
Keyword(s):  
Community Noise ◽  
Noise Impact

Control of Rapid Transit Propulsion System Noise

1984 ◽  
Vol 106 (2) ◽  
pp. 270-277
Author(s):  
P. J. Remington ◽  
N. R. Dixon
Keyword(s):  
High Speed ◽  
Propulsion System ◽  
Laboratory Model ◽  
Rapid Transit ◽  
Blade Passage ◽  
Community Noise ◽  
System Noise ◽  
Cooling Fan ◽  
Urban Rail ◽  
Noise Impact

An extensive series of diagnostic measurements was carried out on an urban rail propulsion system of the type that was found to have the greatest community noise impact. At high speed, 3000 to 4000 rpm, the fan dominates all other sources by 10–15 dBA. At low speed, 1000 to 1500 rpm, fan, gears, and drive motors make comparable noise. A series of tests on a laboratory model of the fan/end housing of a Westinghouse 1447 propulsion motor showed that by modifying the geometry of the end housing posts and reducing the diameter of the cooling fan, the tone at the blade passage frequency was virtually eliminated. In addition, the overall noise was reduced by over 10 dBA while the same airflow was maintained through the fan. When these treatments were applied to the motor itself, it was possible to maintain the same airflow as in the unmodified motor by redesigning the grill over the inlet at the commutator end of the motor. Noise reductions, however, were not as significant as in the laboratory model. Although the blade passage tone was virtually eliminated, overall noise reduction was in the 3 to 6 dBA range, depending on the combination of treatments used.

Aircraft Community Noise Impact Model

1998 ◽  
Vol 1626 (1) ◽  
pp. 58-66 ◽  
Author(s):  
Eric Stusnick ◽  
Richard L. Thompson ◽  
Terence R. Thompson ◽  
Bryan A. Evans ◽  
John DiFelici
Keyword(s):  
Computer Software ◽  
Software System ◽  
Impact Model ◽  
Community Noise ◽  
Noise Impact ◽  
History Of ◽  
Langley Research Center ◽  
Computer Software System ◽  
User Friendly ◽  
The Impact

The Aircraft Community Noise Impact Model (ACNIM) is a computer software system being developed by Wyle Laboratories and Metron, Inc., for the National Aeronautics and Space Administration–Langley Research Center. It is intended to provide a user-friendly tool for analysis of the impact of the noise from aircraft operations on communities near airports. The history of the development of ACNIM and some of its unique features are outlined and the optimization algorithms that are used by ACNIM to produce minimally impacting flight trajectories are discussed in some detail.

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