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Comparison Of Experimental Helicopter Rotor Blade Vortex Interaction Noise With Computational Fluid Dynamic Calculations
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Book Synopsis Comparison of Experimental Helicopter Rotor Blade-vortex Interaction Noise with Computational Fluid Dynamic Calculations by : Megan S. McCluer
Download or read book Comparison of Experimental Helicopter Rotor Blade-vortex Interaction Noise with Computational Fluid Dynamic Calculations written by Megan S. McCluer and published by . This book was released on 1995 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722428778 Total Pages :60 pages Book Rating :4.4/5 (287 download)
Book Synopsis Helicopter Blade-Vortex Interaction Noise with Comparisons to Cfd Calculations by : National Aeronautics and Space Administration (NASA)
Download or read book Helicopter Blade-Vortex Interaction Noise with Comparisons to Cfd Calculations written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-08 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comparison of experimental acoustics data and computational predictions was performed for a helicopter rotor blade interacting with a parallel vortex. The experiment was designed to examine the aerodynamics and acoustics of parallel Blade-Vortex Interaction (BVI) and was performed in the Ames Research Center (ARC) 80- by 120-Foot Subsonic Wind Tunnel. An independently generated vortex interacted with a small-scale, nonlifting helicopter rotor at the 180 deg azimuth angle to create the interaction in a controlled environment. Computational Fluid Dynamics (CFD) was used to calculate near-field pressure time histories. The CFD code, called Transonic Unsteady Rotor Navier-Stokes (TURNS), was used to make comparisons with the acoustic pressure measurement at two microphone locations and several test conditions. The test conditions examined included hover tip Mach numbers of 0.6 and 0.7, advance ratio of 0.2, positive and negative vortex rotation, and the vortex passing above and below the rotor blade by 0.25 rotor chords. The results show that the CFD qualitatively predicts the acoustic characteristics very well, but quantitatively overpredicts the peak-to-peak sound pressure level by 15 percent in most cases. There also exists a discrepancy in the phasing (about 4 deg) of the BVI event in some cases. Additional calculations were performed to examine the effects of vortex strength, thickness, time accuracy, and directionality. This study validates the TURNS code for prediction of near-field acoustic pressures of controlled parallel BVI. McCluer, Megan S. Ames Research Center...
Book Synopsis Helicopter Blade-Vortex Interaction Noise with Comparisons to CFD Calculations by :
Download or read book Helicopter Blade-Vortex Interaction Noise with Comparisons to CFD Calculations written by and published by . This book was released on 1996 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Overset Grid Navier-Stokes/Kirchhoff-surface Method for Rotorcraft Aeroacoustic Predictions by : Earl P. N. Duque
Download or read book An Overset Grid Navier-Stokes/Kirchhoff-surface Method for Rotorcraft Aeroacoustic Predictions written by Earl P. N. Duque and published by . This book was released on 1996 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "This paper describes a new method for computing the flowfield and acoustic signature of arbitrary rotors in forward flight. The overall scheme uses a finite-difference Navier-Stokes solver to compute the aerodynamic flowfield near the rotor blades. The equations are solved on a system of overset grids that allow for prescribed cyclic and flapping blade motions and capture the interactions between the rotor blades and wake. The far-field noise is computed with a Kirchhoff integration over a surface that completely encloses the rotor blades. Flowfield data are interpolated onto this Kirchhoff surface using the same overset-grid techniques that are used for the flowfield solution. As a demonstration of the overall prediction scheme, computed results for far-field noise are compared with experimental data for both high-speed impulsive (HSI) and blade-vortex interaction (BVI) cases. The HSI case showed good agreement with experimental data while a preliminary attempt at the BVI case did not. The computations clearly show that temporal accuracy, spatial accuracy and grid resolution in the Navier-Stokes solver play key roles in the overall accuracy of the predicted noise. These findings will be addressed more closely in future BVI computations. Overall, the overset-grid CFD scheme provides a powerful new framework for the prediction of helicopter noise."
Book Synopsis Helicopter Blade-vortex Interaction Noise with Comparisons to CFD Calculations by : Megan S. McCluer
Download or read book Helicopter Blade-vortex Interaction Noise with Comparisons to CFD Calculations written by Megan S. McCluer and published by . This book was released on 1996 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis New Computational Methods for the Prediction and Analysis of Helicopter Noise by : Roger C. Strawn
Download or read book New Computational Methods for the Prediction and Analysis of Helicopter Noise written by Roger C. Strawn and published by . This book was released on 1996 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: "This paper describes several new methods to predict and analyze rotorcraft noise. These methods are: 1) a combined computational fluid dynamics and Kirchhoff scheme for far-field noise predictions, 2) parallel computer implementation of the Kirchhoff integrations, 3) audio and visual rendering of the computed acoustic predictions over large far-field regions, and 4) acoustic tracebacks to the Kirchhoff surface to pinpoint the sources of the rotor noise. The paper describes each method and presents sample results for three test cases. The first case consists of in-plane high-speed impulsive noise and the other two cases show idealized parallel and oblique blade-vortex interactions. The computed results show good agreement with available experimental data but convey much more information about the far-field noise propagation. When taken together, these new analysis methods exploit the power of new computer technologies and offer the potential to significantly improve our prediction and understanding of rotorcraft noise."
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 A Free-Wake Euler and Navier-Stokes CFD Method and Its Application to Helicopter Rotors Including Dynamic Stall by :
Download or read book A Free-Wake Euler and Navier-Stokes CFD Method and Its Application to Helicopter Rotors Including Dynamic Stall written by and published by . This book was released on 1993 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report summarizes the results of the research in two parts. Part I describes the development and application of a free-wake Euler and Navier- Stokes computational fluid dynamics method, called 'TURNS', for helicopter applications. This finite-difference, implicit, upwind numerical method uses structured grids, and has been used for calculating the viscous, three- dimensional flow-fields of rotors in hover, forward flight, blade-vortex interactions, and high speed impulsive noise. The good agreement of numerical results with experiments for surface pressures, wake trajectory, thrust, power, Figure of Merit, and acoustic wave forms indicate the accuracy and suitability of the numerical method. It is demonstrated that both aerodynamics and acoustics information can be obtained in a single solution of the governing equations. In Part II, the unsteady flowfield results of a two-dimensional oscillating wing are presented for five widely used turbulence models and compared with experiments. The accuracy and suitability of turbulence models for unsteady separated flow axe discussed. Free-wake, Hover, Viscous, Three-dimensional, Forward flight, Helicopter, Dynamic stall, Light-stall, Deep-stall, Unsteady, Euler, Navier-stokes, Blade-vortex interaction, Impulsive noise.
Book Synopsis The Utilization of Computational Fluid Dynamics to Reduce Blade Vortex Interaction Noise by : Ebony Elizabeth Graves
Download or read book The Utilization of Computational Fluid Dynamics to Reduce Blade Vortex Interaction Noise written by Ebony Elizabeth Graves and published by . This book was released on 2003 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Acoustic Measurements from a Rotor Blade-vortex Interaction Noise Experiment in the German-Dutch Wind Tunnel (DNW) by : Ruth McVoy Martin
Download or read book Acoustic Measurements from a Rotor Blade-vortex Interaction Noise Experiment in the German-Dutch Wind Tunnel (DNW) written by Ruth McVoy Martin and published by . This book was released on 1988 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: Acoustic data are presented from a 40-percent-scale model of the four-bladed BO-105 helicopter main rotor, tested in a large aeroacoustic wind tunnel. Rotor blade-vortex interaction (BVI) noise data in the low-speed flight range were acquired using a traversing in-flow microphone array. The experimental apparatus, testing procedures, calibration results, and experimental objectives are fully described. A large representative set of averaged acoustic signals are presented.
Book Synopsis Acoustic Measurements from a Rotor Blade-vortex Interaction Noise Experiment in the German-Dutch Wind Tunnel (DNW) by :
Download or read book Acoustic Measurements from a Rotor Blade-vortex Interaction Noise Experiment in the German-Dutch Wind Tunnel (DNW) written by and published by . This book was released on 1988 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Calculation of Helicopter Rotor Blade/vortex Interaction by Navier-Stokes Procedures by :
Download or read book Calculation of Helicopter Rotor Blade/vortex Interaction by Navier-Stokes Procedures written by and published by . This book was released on 1987 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Investigation of Blade-vortex Interaction Noise Using Computational Fluid Dynamics by : Romuald Morvant
Download or read book The Investigation of Blade-vortex Interaction Noise Using Computational Fluid Dynamics written by Romuald Morvant and published by . This book was released on 2004 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Helicopter Model Rotor-blade Vortex Interaction Impulsive Noise: Scalability and Parametric Variations by :
Download or read book Helicopter Model Rotor-blade Vortex Interaction Impulsive Noise: Scalability and Parametric Variations written by and published by . This book was released on 1984 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Special Opportunities in Helicopter Aerodynamics by : W. J. McCroskey
Download or read book Special Opportunities in Helicopter Aerodynamics written by W. J. McCroskey and published by . This book was released on 1983 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerodynamic research relating to modern helicopters includes the study of three-dimensional, unsteady, nonlinear flow fields. A selective review is made of some of the phenomenon that hamper the development of satisfactory engineering prediction techniques, but which provides a rich source of research opportunities: flow separations, compressibility effects, complex vortical wakes, and aerodynamic interference between components. Several examples of work in progress are given, including dynamic stall alleviation, the development of computational methods for transonic flow, rotor-wake predictions, and blade-vortex interactions. (Author).
Book Synopsis Rotorcraft Blade-vortex Interaction Noise Reduction Through Attitude and Flight Parameter Variations by : Juan Abelló
Download or read book Rotorcraft Blade-vortex Interaction Noise Reduction Through Attitude and Flight Parameter Variations written by Juan Abelló and published by . This book was released on 2004 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experimental Blade Vortex Interaction Noise Characteristics of a Utility Helicopter at 1/4 Scale by :
Download or read book Experimental Blade Vortex Interaction Noise Characteristics of a Utility Helicopter at 1/4 Scale written by and published by . This book was released on 1984 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:
