Impulsive Noise Due To Transonic Blade Vortex Interactions PDF Download
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Author | : Shyue-bin Chang |
Publisher | : |
Total Pages | : 354 |
Release | : 1985 |
Genre | : Aerodynamic noise |
ISBN | : |
Download Impulsive Noise Due to Transonic Blade-vortex Interactions Book in PDF, ePub and Kindle
Author | : F. H. Schmitz |
Publisher | : |
Total Pages | : 110 |
Release | : 1983 |
Genre | : |
ISBN | : |
Download Helicopter Impulsive Noise: Theoretical and Experimental Status Book in PDF, ePub and Kindle
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 | : Anastasios Sotirios Lyrintzis |
Publisher | : |
Total Pages | : 306 |
Release | : 1988 |
Genre | : Aerodynamics, Transonic |
ISBN | : |
Download Transonic Blade-vortex Interactions Book in PDF, ePub and Kindle
Author | : |
Publisher | : |
Total Pages | : 22 |
Release | : 1989 |
Genre | : |
ISBN | : |
Download Reduction of Blade-vortex Interaction Noise Using Higher Harmonic Pitch Control Book in PDF, ePub and Kindle
An acoustics test using an aeroelastically scaled rotor was conducted to examine the effectiveness of higher harmonic blade pitch control for the reduction of impulsive blade-vortex interaction (BVI) noise. A four-bladed, 110 in. diameter, articulated rotor model was tested in a heavy gas (Freon-12) medium in the Transonic Dynamics Tunnel. Noise and vibration measurements were made for a range of matched flight conditions, where prescribed (open-loop) higher harmonic pitch was superimposed on the normal (baseline) collective and cyclic trim pitch. For the inflow-microphone noise measurements, advantage was taken of the reverberance in the hard walled tunnel by using a sound power determination approach. Initial findings from on-line data processing for three of the test microphones are reported for a 4/rev (4P) collective pitch control for a range of input amplitudes and phases. By comparing these results to corresponding baseline (no control) conditions, significant noise reductions (4- 5 dB) were found for low-speed descent conditions, where helicopter BVI noise was most intense. For other rotor flight conditions, the overall noise was found to increase. All cases show increased vibration levels.
Author | : N. Ng |
Publisher | : |
Total Pages | : |
Release | : 1997 |
Genre | : |
ISBN | : |
Download Numerical Investigations of the Transonic Blade-vortex Interaction Book in PDF, ePub and Kindle
Author | : Xue Yu |
Publisher | : |
Total Pages | : 346 |
Release | : 1994 |
Genre | : |
ISBN | : |
Download The Computation and Analysis of Helicopter Impulsive Noise Book in PDF, ePub and Kindle
Author | : |
Publisher | : |
Total Pages | : 594 |
Release | : 1986 |
Genre | : Shock (Mechanics) |
ISBN | : |
Download The Shock and Vibration Digest Book in PDF, ePub and Kindle
Author | : Harvey H. Hubbard |
Publisher | : |
Total Pages | : 616 |
Release | : 1991 |
Genre | : Aerodynamic noise |
ISBN | : |
Download Aeroacoustics of Flight Vehicles Book in PDF, ePub and Kindle
Author | : |
Publisher | : |
Total Pages | : 720 |
Release | : 1988 |
Genre | : Aeronautics |
ISBN | : |
Download Scientific and Technical Aerospace Reports Book in PDF, ePub and Kindle
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author | : Rajneesh K. Singh |
Publisher | : |
Total Pages | : 532 |
Release | : 1999 |
Genre | : Aerodynamics, Transonic |
ISBN | : |
Download Transonic Effects on Aerodynamics and Acoustics of Blade-vortex Interaction Book in PDF, ePub and Kindle