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Correlation Of Helicopter Impulsive Noise From Blade Vortex Interaction With Rotor Mean Inflow Book in PDF, ePub and Kindle version is available to download in english. Read online anytime anywhere directly from your device. Click on the download button below to get a free pdf file of Correlation Of Helicopter Impulsive Noise From Blade Vortex Interaction With Rotor Mean Inflow book. This book definitely worth reading, it is an incredibly well-written.
Author : Andrew B. Connor
Publisher : Unknown
Page : 28 pages
File Size : 43,7 Mb
Release : 1987
Category : Helicopters
ISBN : UIUC:30112106613364
Author : Andrew B. Connor
Publisher : Unknown
Page : 28 pages
File Size : 49,8 Mb
Release : 1987
Category : Electronic
ISBN : NASA:31769000440522
Author : Anonim
Publisher : Unknown
Page : 36 pages
File Size : 54,7 Mb
Release : 1984
Category : Electronic
ISBN : NASA:31769000562911
Acoustic data taken in the anechoic Deutsch-NIederlaendischer Windkanal (DNW) have documented the blade-vortex interaction (BVI) impulsive noise radiated from 1/7-scale model main rotor of the AH-1 series helicopter. Average model-scale data were compared with averaged full-scale, in-flight acoustic data under similar nondimensional test conditions. At low advance ratios (mu = 0.164-0.194), the data scale remarkably well in level and waveform shape, and also duplicate the directivity pattern of BVI impulsive noise. At moderate advance ratios (mu = 0.224-0.270), the scaling deteriorates, suggesting that the model-scale rotor is not adequately simulating the full-scale BVI noise; presently, no proved explanation of this discrepancy exists. Carefully performed parametric variations over a complete matrix of testing conditions have shown that all of the four governing nondimensional parameters -- tip Mach number at hover, advance ratio, local inflow ratio, and thrust coefficient -- are highly sensitive to BVI noise radiation. Keywords: Helicopter noise; Blade vortex interaction; Measured acoustics.
Author : Anonim
Publisher : Unknown
Page : 96 pages
File Size : 40,9 Mb
Release : 1988
Category : Aeronautics
ISBN : STANFORD:36105024715976
Author : F. H. Schmitz
Publisher : Unknown
Page : 110 pages
File Size : 40,8 Mb
Release : 1983
Category : Electronic
ISBN : NASA:31769000557143
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 : Anonim
Publisher : Unknown
Page : 28 pages
File Size : 53,8 Mb
Release : 1987
Category : Science
ISBN : STANFORD:36105024803558
Author : Anonim
Publisher : Unknown
Page : 300 pages
File Size : 53,6 Mb
Release : 1991
Category : Aeronautics
ISBN : MINN:30000005718667
Author : Anonim
Publisher : Unknown
Page : 1224 pages
File Size : 42,8 Mb
Release : 2024-07-03
Category : Government publications
ISBN : WISC:89117117531
Author : Anonim
Publisher : Unknown
Page : 1586 pages
File Size : 46,7 Mb
Release : 1990
Category : Government publications
ISBN : UIUC:30112063914490
Author : Anonim
Publisher : Unknown
Page : 360 pages
File Size : 51,9 Mb
Release : 1993
Category : Aeronautics
ISBN : MINN:31951P00987791K
Author : Anonim
Publisher : Unknown
Page : 538 pages
File Size : 47,7 Mb
Release : 1991
Category : Aeronautics
ISBN : UOM:39015023295143
Author : Anonim
Publisher : Unknown
Page : 100 pages
File Size : 45,9 Mb
Release : 1979
Category : Electronic
ISBN : NASA:31769000546351
Author : J. Fitzgerald
Publisher : Unknown
Page : 158 pages
File Size : 48,5 Mb
Release : 1988
Category : Rotors (Helicopters)
ISBN : NASA:31769000512387
Author : États-Unis. National aeronautics and space administration
Publisher : Unknown
Page : 76 pages
File Size : 50,5 Mb
Release : 1988
Category : Electronic
ISBN : NASA:31769000660327
Author : Anonim
Publisher : Unknown
Page : 44 pages
File Size : 54,5 Mb
Release : 2000
Category : Electronic
ISBN : NASA:31769000630833
Within a program designed to develop experimental techniques for measuring the trajectory and structure of vortices trailing from the tips of rotor blades, the present preliminary study focuses on a method for quantifying the trajectory of the trailing vortex during descent flight conditions. This study also presents rotor loads and blade surface pressures for a range of tip-path plane angles and Mach numbers. Blade pressures near the leading edge and along the outer radius are compared with data obtained on the same model rotor, but in open jet facilities. A triangulation procedure based on two directable laser-light sheets, each containing an embedded reference, proved effective in defining the spatial coordinates of the trailing vortex. When interrogating a cross section of the flow that contains several trailing vortices, the greatest clarity was found to result when the flow is uniformly seeded. Surface pressure responses during blade-vortex interactions appeared equally sensitive near the leading edge and along the outer portion of the blade, but diminished rapidly as the distance along the blade chord increased. The pressure response was virtually independent of whether the tip-path plane angle was obtained through shaft tilt or cyclic pitch. Although the shape and frequency of the pressure perturbations on the advancing blade during blade-vortex interaction are similar to those obtained in open-jet facilities, the angle of the tip-path plane may need to be lower than the range covered in this study.