Helicopter Impulsive Noise: Theoretical and Experimental Status PDF Download
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Author: F. H. Schmitz
Publisher:
ISBN:
Category :
Languages : en
Pages : 110
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Book Description
The theoretical and experimental status of helicopter impulsive noise is reviewed. The two major source mechanisms of helicopter impulsive noise are addressed: high-speed impulsive noise and blade-vortex interaction impulsive noise. A thorough physical explanation of both generating mechanisms is presented together with model and full-scale measurements of the phenomena. Current theoretical prediction methods are compared with experimental findings of isolated rotor tests. The noise generating mechanisms of high speed impulsive noise are fairly well understood - theory and experiment compare nicely over Mach number ranges typical of today's helicopters. For the case of blade-vortex interaction noise, understanding of noise generating mechanisms and theoretical comparison with experiment are less satisfactory. Several methods for improving theory-experiment are suggested.
Author: A. R. George
Publisher:
ISBN:
Category :
Languages : en
Pages : 20
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Book Description
Research was conducted on aspect of noise generation by helicopters. A general review of helicopter noise was prepared and published as one part of the work. Methods were developed for the analysis of high frequency broadband noise from rotors. Physical and analytical approximations were devised which allow practical calculation of noise from various loading mechanisms. Atmospheric turbulence noise was investigated including some effects of inflow distribution. A method for predicting trailing edge noise for rotors was developed. The results show that trailing edge noise can be quite important at high frequencies when the small scale components of ingested turbulence are weak compared to those of the blade boundary layer turbulence. In the area of high speed noise from high Mach number advancing blades the research was primarily concentrated on the radiated sound from the Lighthill stress associated with the occurrence of unsteady shock formation and disappearance on advancing transonic rotor blades. A simplified model of an impulsively started and stopped shock was used as the known near field in order to find the far field radiation.
Author: F. H. Schmitz
Publisher:
ISBN:
Category :
Languages : en
Pages : 110
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Book Description
The theoretical and experimental status of helicopter impulsive noise is reviewed. The two major source mechanisms of helicopter impulsive noise are addressed: high-speed impulsive noise and blade-vortex interaction impulsive noise. A thorough physical explanation of both generating mechanisms is presented together with model and full-scale measurements of the phenomena. Current theoretical prediction methods are compared with experimental findings of isolated rotor tests. The noise generating mechanisms of high speed impulsive noise are fairly well understood - theory and experiment compare nicely over Mach number ranges typical of today's helicopters. For the case of blade-vortex interaction noise, understanding of noise generating mechanisms and theoretical comparison with experiment are less satisfactory. Several methods for improving theory-experiment are suggested.
Author: Harry Sternfeld
Publisher:
ISBN:
Category : Helicopters
Languages : en
Pages : 84
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Author: Ying-Chieh Albert Lee
Publisher:
ISBN:
Category : Helicopters
Languages : en
Pages : 350
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 178
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 84
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 104
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Author: Terence Stephen Allan Denton
Publisher:
ISBN:
Category : Helicopters
Languages : en
Pages : 326
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Book Description
Author: Thomas F. Brooks
Publisher:
ISBN:
Category : Rotors (Helicopters)
Languages : en
Pages : 72
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 454
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