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Experimental Assessment Of Helicopter Rotor Turbulence Ingestion Noise In Hover
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Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722386559 Total Pages :68 pages Book Rating :4.3/5 (865 download)
Book Synopsis Experimental Assessment of Helicopter Rotor Turbulence Ingestion Noise in Hover by : National Aeronautics and Space Administration (NASA)
Download or read book Experimental Assessment of Helicopter Rotor Turbulence Ingestion Noise in Hover written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-06 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experiment was conducted to assess the accuracy of a theory for non-isotropic turbulence ingestion. In order to generate non-isotropic turbulence in a controlled environment, a scale model rotor in a closed chamber was used so that the turbulence generated by the rotor was reingested by the recirculating flow. Simultaneous measurements of turbulence inflow properties and far field acoustics were acquired. Measurements confirmed that the inflow turbulence was highly non-isotropic. The measured aerodynamic properties were used as inputs for the noise prediction procedure. The general agreement between the non-isotropic noise prediction procedure and the experiment was good, although the procedure generally overpredicts the quasi-tonal low to mid range frequencies and underpredicts the higher broadband signals. The predicted sound power level as a function of polar angle was in close agreement with measurements, except near the rotor plane, which is not modeled by the present analysis. It is determined that the most sensitive parameter influencing the predicted noise was the turbulence intensity. Simonich, J. C. and Schlinker, R. H. and Amiet, R. K. Unspecified Center...
Book Synopsis Experimental Assessment of Helicopter Rotor Turbulence Ingestion Noise in Hover by : John Charles Simonich
Download or read book Experimental Assessment of Helicopter Rotor Turbulence Ingestion Noise in Hover written by John Charles Simonich and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experimental Assessment of Helicopter Rotor Turbulence Ingestion Noise in Hover by :
Download or read book Experimental Assessment of Helicopter Rotor Turbulence Ingestion Noise in Hover written by and published by . This book was released on 1989 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Noise of a Model Helicopter Rotor Due to Ingestion of Turbulence by : Robert William Paterson
Download or read book Noise of a Model Helicopter Rotor Due to Ingestion of Turbulence written by Robert William Paterson and published by . This book was released on 1979 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Noise of a Model Helicopter Rotor Due to Ingestion of Turbulence by : Robert W. Paterson
Download or read book Noise of a Model Helicopter Rotor Due to Ingestion of Turbulence written by Robert W. Paterson and published by . This book was released on 1979 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Helicopter Impulsive Noise: Theoretical and Experimental Status by : F. H. Schmitz
Download or read book Helicopter Impulsive Noise: Theoretical and Experimental Status written by F. H. Schmitz and published by . This book was released on 1983 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Helicopter Rotor Noise Due to Ingestion of Atmospheric Turbulence by : John C. Simonich
Download or read book Helicopter Rotor Noise Due to Ingestion of Atmospheric Turbulence written by John C. Simonich and published by . This book was released on 1986 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: A theoretical study was conducted to develop an analytical prediction method for helicopter main rotor noise due to the ingestion of atmospheric turbulence. This study incorporates an atmospheric turbulence model, a rotor mean flow contraction model and a rapid distortion turbulence model which together determine the statistics of the non-isotropic turbulence at the rotor plane. Inputs to the combined mean inflow and turbulence models are controlled by atmospheric wind characteristics and helicopter operating conditions. A generalized acoustic source model was used to predict the far field noise generated by the non-isotropic flow incident on the rotor. Absolute levels for acoustic spectra and directivity patterns were calculated for full scale helicopters, without the use of empirical or adjustable constants. Comparisons between isotropic and non-isotropic turbulence at the rotor face demonstrated pronounced differences in acoustic spectra. Turning and contraction of the flow for hover and low speed vertical ascent cases result in a 3 dB increase in the acoustic spectrum energy and a 10 dB increase in tone levels. Compared to trailing edge noise, turbulence ingestion noise is the dominant noise mechanism below approximately 30 rotor harmonics, while above 100 harmonics, trailing edge noise levels exceed turbulence ingestion noise by 25 dB.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Helicopter Rotor Noise Due to Ingestion of Atmospheric Turbulence by :
Download or read book Helicopter Rotor Noise Due to Ingestion of Atmospheric Turbulence written by and published by . This book was released on 1986 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :David Rudolf Polak Publisher :Ann Arbor, Mich. : University Microfilms International ISBN 13 : Total Pages :634 pages Book Rating :4.E/5 ( download)
Book Synopsis Experimental and Computational Investigation of Tilt Rotor Hover Aeroacoustics by : David Rudolf Polak
Download or read book Experimental and Computational Investigation of Tilt Rotor Hover Aeroacoustics written by David Rudolf Polak and published by Ann Arbor, Mich. : University Microfilms International. This book was released on 1996 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Experimental Study of Helicopter Rotor Impulsive Noise by : William E. Bausch
Download or read book An Experimental Study of Helicopter Rotor Impulsive Noise written by William E. Bausch and published by . This book was released on 1971 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of a study of helicopter rotor impulsive noise (RIN) are presented. Rotor noise, together with rotor blade dynamic and pressure data, was measured during hover and cruise of a CH-53A helicopter for use in a correlation study of calculated and measured noise. In addition, the rotor rotational noise analysis described in U.S. Army Aviation Materiel Laboratories (USAAVLABS) technical Report 70-1B was modified to reduce computation time and to include blade flapping and coning motions. The inclusion of these motions, however, is shown to have little effect on the predicted noise. Correlation of calculated and measured noise harmonic amplitudes is generally within 5 dB through the third harmonic at distances less than 1000 feet in front of the helicopter. Waveform correlation of calculated and measured time histories of acoustic pressure is good. RIN is identified as being primarily a rotational noise phenomenon, ordered at the blade passage frequency and its harmonics, rather than amplitude modulated broadband noise. Hover RIN is shown to be due to vortex interference (blade/wake interaction RIN), while cruise RIN is shown to be due to the combination of acoustic effects of a high subsonic tip Mach number on wave propagation and blade drag, and is referred to as advancing blade RIN.
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722910808 Total Pages :192 pages Book Rating :4.9/5 (18 download)
Book Synopsis A Study of Rotor Broadband Noise Mechanisms and Helicopter Tail Rotor Noise by : National Aeronautics and Space Administration (NASA)
Download or read book A Study of Rotor Broadband Noise Mechanisms and Helicopter Tail Rotor Noise written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-17 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: The rotor broadband noise mechanisms considered are the following: (1) lift fluctuation due to turbulence ingestion; (2) boundary layer/trailing edge interaction; (3) tip vortex formation; and (4) turbulent vortex shedding from blunt trailing edge. Predictions show good agreement with available experimental data. The study shows that inflow turbulence is the most important broadband noise source for typical helicopters' main rotors at low- and mid-frequencies. Due to the size difference, isolated helicopter tail rotor broadband noise is not important compared to the much louder main rotor broadband noise. However, the inflow turbulence noise from a tail rotor can be very significant because it is operating in a highly turbulent environment, ingesting wakes from upstream components of the helicopter. The study indicates that the main rotor turbulent wake is the most important source of tail rotor broadband noise. The harmonic noise due to ingestion of main rotor tip vortices is studied. Chou, Shau-Tak Rudy Unspecified Center AERODYNAMIC NOISE; AIRCRAFT NOISE; BROADBAND; HELICOPTER TAIL ROTORS; HELICOPTERS; NOISE GENERATORS; ROTARY WINGS; ROTOR AERODYNAMICS; BLUNT TRAILING EDGES; HARMONIC OSCILLATION; NOISE PREDICTION (AIRCRAFT); TURBULENT WAKES; VORTEX SHEDDING; VORTICES...
Book Synopsis An Experimental Investigation of Vortex Stability, Tip Shapes, Compressibility, and Noise for Hovering Model Rotors by : James L. Tangler
Download or read book An Experimental Investigation of Vortex Stability, Tip Shapes, Compressibility, and Noise for Hovering Model Rotors written by James L. Tangler and published by . This book was released on 1973 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Experimental and Theoretical Study of Helicopter Rotor Noise by : Ying-Chieh Albert Lee
Download or read book An Experimental and Theoretical Study of Helicopter Rotor Noise written by Ying-Chieh Albert Lee and published by . This book was released on 1975 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experimental Evaluation of Active and Passive Means of Alleviating Rotor Impulsive Noise in Descent Flight by :
Download or read book Experimental Evaluation of Active and Passive Means of Alleviating Rotor Impulsive Noise in Descent Flight written by and published by . This book was released on 1979 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Shock and Vibration Digest written by and published by . This book was released on 1983 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Development of Experimental Techniques for the Study of Helicopter Rotor Noise by :
Download or read book The Development of Experimental Techniques for the Study of Helicopter Rotor Noise written by and published by . This book was released on 1974 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
