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Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781720382652 Category : Languages : en Pages : 74
Book Description
An analysis has been performed of measured and predicted aircraft noise levels around Denver International Airport. A detailed examination was made of 90 straight-out departures that yielded good measurements on multiple monitors. Predictions were made with INM 5, INM 6 and the simulation model NMSIM. Predictions were consistently lower than measurements, less so for the simulation model than for the integrated models. Lateral directivity ("installation effect") patterns were seen which are consistent with other recent measurements. Atmospheric absorption was determined to be a significant factor in the underprediction. Calculations of atmospheric attenuation were made over a full year of upper air data at seven locations across the United States. It was found that temperature/humidity effects could cause variations of up to +/-4 dB, depending on season, for the sites examined. It was concluded that local temperature and humidity should be accounted for in aircraft noise modeling.Plotkin, Kenneth J. and Shepherd, Kevin P. (Technical Monitor)Langley Research CenterNOISE PREDICTION; AIRCRAFT NOISE; ACOUSTIC PROPAGATION; SOUND PROPAGATION; NOISE INTENSITY; MODELS; TEMPERATURE EFFECTS; DIRECTIVITY
Author: National Aeronautics and Space Administration (NASA) Publisher: Createspace Independent Publishing Platform ISBN: 9781720382652 Category : Languages : en Pages : 74
Book Description
An analysis has been performed of measured and predicted aircraft noise levels around Denver International Airport. A detailed examination was made of 90 straight-out departures that yielded good measurements on multiple monitors. Predictions were made with INM 5, INM 6 and the simulation model NMSIM. Predictions were consistently lower than measurements, less so for the simulation model than for the integrated models. Lateral directivity ("installation effect") patterns were seen which are consistent with other recent measurements. Atmospheric absorption was determined to be a significant factor in the underprediction. Calculations of atmospheric attenuation were made over a full year of upper air data at seven locations across the United States. It was found that temperature/humidity effects could cause variations of up to +/-4 dB, depending on season, for the sites examined. It was concluded that local temperature and humidity should be accounted for in aircraft noise modeling.Plotkin, Kenneth J. and Shepherd, Kevin P. (Technical Monitor)Langley Research CenterNOISE PREDICTION; AIRCRAFT NOISE; ACOUSTIC PROPAGATION; SOUND PROPAGATION; NOISE INTENSITY; MODELS; TEMPERATURE EFFECTS; DIRECTIVITY
Author: Oleksandr Zaporozhets Publisher: CRC Press ISBN: 0203888820 Category : Technology & Engineering Languages : en Pages : 432
Book Description
Aircraft noise has adverse impacts on passengers, airport staff and people living near airports, it thus limits the capacity of regional and international airports throughout the world. Reducing perceived noise of aircraft involves reduction of noise at source, along the propagation path and at the receiver. Effective noise control demands highly s
Author: John J. Schauer Publisher: ISBN: Category : Languages : en Pages : 55
Book Description
Aircraft engine acoustical lining impedance models, ray acoustics, hydrodynamic modes, and transient analysis of sound propagation in variable area duct studies were applied to aircraft noise prediction. The effects of several duct lining configurations in a TF33 P5 and a CFM56 engined KC-135B aircraft were predicted. The prediction was based on a model corrected to fit flight noise data and modified by including theoretical duct noise attenuation predictions. The transient solution of variable area ducts permitted the prediction of sound propgation in bullet nose inlets for no low and was moderately successful when a potential flow was included with low Mach numbers. Volume I contains the technical report and analysis. Volume II contains the user's manuals and listings of the computer codes developed. (Author).
Author: Thomas Rossing Publisher: Springer Science & Business Media ISBN: 0387304460 Category : Science Languages : en Pages : 1179
Book Description
This is an unparalleled modern handbook reflecting the richly interdisciplinary nature of acoustics edited by an acknowledged master in the field. The handbook reviews the most important areas of the subject, with emphasis on current research. The authors of the various chapters are all experts in their fields. Each chapter is richly illustrated with figures and tables. The latest research and applications are incorporated throughout, including computer recognition and synthesis of speech, physiological acoustics, diagnostic imaging and therapeutic applications and acoustical oceanography. An accompanying CD-ROM contains audio and video files.
Author: Ira R. Schwartz Publisher: ISBN: 9781600863011 Category : Airplanes Languages : en Pages : 307
Book Description
"The papers in this volume deal with recent research into acoustic-wave propagation through the atmosphere and progress in aeroacoustic instrumentation, facilities, and test techniques. Topics include the propagation of aircraft noise over long distances in the lower atmosphere, measured effects of turbulence on the rise time of a weak shock, sound scattering from atmospheric turbulence, saturation effects associated with sound propagation in a turbulent medium, and a computer model of the lightning-thunder process. Other papers discuss the development of a computer system for aircraft noise prediction; aircraft flyover noise measurements; and theories and methods for the prediction of ground effects on aircraft noise propagation, for the prediction of airframe aerodynamic noise, for turbine noise prediction, and for combustion noise prediction. Attention is also given to the use of Hartmann generators as sources of high-intensity sound in a large absorption flow-duct facility, an outdoor jet noise facility, factors in the design and performance of free-jet acoustic wind tunnels, and the use of a laser shadowgraph for jet noise diagnosis."--Publisher description.
Author: Publisher: ISBN: Category : Languages : en Pages : 340
Book Description
The fourth in a series of NASA/SAE Interior Noise Workshops was held on May 19 and 20, 1992 at the Graf Zeppelin Haus in Friedrichshafen, Germany. The theme of the workshop was new technology and applications for aircraft interior noise with emphasis on source noise prediction; cabin noise control, including active and passive methods; and cabin interior noise test procedures. This report is a compilation of the presentations made at the meeting which addressed the above issues.
Author: William Roberto Wolf Publisher: Stanford University ISBN: Category : Languages : en Pages : 238
Book Description
The development of physics-based noise prediction tools for analysis of aerodynamic noise sources is of paramount importance since noise regulations have become more stringent. Direct simulation of aerodynamic noise remains prohibitively expensive for engineering problems because of the resolution requirements. Therefore, hybrid approaches that consist of predicting nearfield flow quantities by a suitable CFD simulation and farfield sound radiation by aeroacoustic integral methods are more attractive. In this work, we apply the fast multipole method (FMM) to accelerate the solution of boundary integral equation methods such as the boundary element method (BEM) and the Ffowcs Williams & Hawkings (FWH) acoustic analogy formulation. The FMM-BEM is implemented for the solution of acoustic scattering problems and the effects of non-uniform potential flows on acoustic scattering are investigated. The FMM-FWH is implemented for the solution of two and three-dimensional problems of sound propagation. The effects of flow convection and non-linear quadrupole sources are assessed through the study of sound generated by unsteady laminar flows. Finally, a hybrid methodology is applied for the investigation of airfoil noise. This study is important for the design of aerodynamic shapes such as wings and high-lift devices, as well as wind turbine blades, fans and propellers. The present investigation of airfoil self-noise generation and propagation concerns the broadband noise that arises from the interaction of turbulent boundary layers with the airfoil trailing edge and tonal noise that arises from vortex shedding generated by laminar boundary layers. Nearfield acoustic sources are computed using compressible large eddy simulation (LES) and acoustic predictions are performed by the FMM-FWH. Numerical simulations are conducted for a NACA0012 airfoil with tripped boundary layers and blunt rounded trailing edge at different Mach numbers and angles of incidence. The effects of non-linear quadrupole sources and convection are assessed. In order to validate the numerical solutions, flow simulation and acoustic prediction results are compared to experimental data available in the literature and excellent agreement is observed.
Author: National Aeronautics and Space Administration (NASA)
Author: National Aeronautics and Space Administration (NASA)
Author: Oleksandr Zaporozhets
Author: Harvey H. Hubbard
Author: John J. Schauer
Author: Thomas Rossing
Author: Jianyong Li
Author: Ira R. Schwartz
Author: John P. Raney
Author: 
Author: William Roberto Wolf