Download or read book Acoustic Treatment Design Scaling Methods Volume 4 Numerical Simulation of the Nonlinear Acoustic Impedance of a Perforated Plate Single Degree Of Freedom Resonator Using a Time Domain Finite Difference Method written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-29 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: Single-degree-of-freedom resonators consisting of honeycomb cells covered by perforated facesheets are widely used as acoustic noise suppression liners in aircraft engine ducts. The acoustic resistance and mass reactance of such liners are known to vary with the intensity of the sound incident upon the panel. Since the pressure drop across a perforated liner facesheet increases quadratically with the flow velocity through the facesheet, this is known as the nonlinear resistance effect. In the past, two different empirical frequency domain models have been used to predict the Sound Pressure Level effect of the incident wave on the perforated liner impedance, one that uses the incident particle velocity in isolated narrowbands, and one that models the particle velocity as the overall velocity. In the absence of grazing flow, neither frequency domain model is entirely accurate in predicting the nonlinear effect that is measured for typical perforated sheets. The time domain model is developed in an attempt to understand and improve the model for the effect of spectral shape and amplitude of multi-frequency incident sound pressure on the liner impedance. A computer code for the time-domain finite difference model is developed and predictions using the models are compared to current frequency-domain models.Kraft, R. E.Glenn Research Center; Langley Research CenterDEGREES OF FREEDOM; NOISE REDUCTION; PRESSURE EFFECTS; SOUND INTENSITY; HONEYCOMB STRUCTURES; AIRCRAFT ENGINES; GRAZING FLOW; NOISE (SOUND); FLOW VELOCITY; MATHEMATICAL MODELS; RESONATORS; SOUND PRESSURE; NONLINEARITY
Download or read book Acoustic Treatment Design Scaling Methods written by R. E. Kraft and published by . This book was released on 1999 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Acoustic Treatment Design Scaling Methods written by and published by . This book was released on 1999 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA Langley Scientific and Technical Information Output 1999 written by and published by . This book was released on 2000 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Acoustic Treatment Design Scaling Methods Volume 2 Advanced Treatment Impedance Models for High Frequency Ranges written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-29 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary purpose of this study is to develop improved models for the acoustic impedance of treatment panels at high frequencies, for application to subscale treatment designs. Effects that cause significant deviation of the impedance from simple geometric scaling are examined in detail, an improved high-frequency impedance model is developed, and the improved model is correlated with high-frequency impedance measurements. Only single-degree-of-freedom honeycomb sandwich resonator panels with either perforated sheet or "linear" wiremesh faceplates are considered. The objective is to understand those effects that cause the simple single-degree-of- freedom resonator panels to deviate at the higher-scaled frequency from the impedance that would be obtained at the corresponding full-scale frequency. This will allow the subscale panel to be designed to achieve a specified impedance spectrum over at least a limited range of frequencies. An advanced impedance prediction model has been developed that accounts for some of the known effects at high frequency that have previously been ignored as a small source of error for full-scale frequency ranges.Kraft, R. E. and Yu, J. and Kwan, H. W.Langley Research CenterACOUSTIC IMPEDANCE; HIGH FREQUENCIES; AIRCRAFT MODELS; SCALE MODELS; AIRCRAFT NOISE; NOISE PREDICTION (AIRCRAFT); AEROACOUSTICS; HONEYCOMB STRUCTURES; PANELS; SANDWICH STRUCTURES; FAN BLADES
Download or read book Acoustic Treatment Design Scaling Methods Volume 3 Test Plans Hardware Results and Evaluation written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-27 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability to design, build, and test miniaturized acoustic treatment panels on scale-model fan rigs representative of the full-scale engine provides not only a cost-savings, but an opportunity to optimize the treatment by allowing tests of different designs. To be able to use scale model treatment as a full-scale design tool, it is necessary that the designer be able to reliably translate the scale model design and performance to an equivalent full-scale design. The primary objective of the study presented in this volume of the final report was to conduct laboratory tests to evaluate liner acoustic properties and validate advanced treatment impedance models. These laboratory tests include DC flow resistance measurements, normal incidence impedance measurements, DC flow and impedance measurements in the presence of grazing flow, and in-duct liner attenuation as well as modal measurements. Test panels were fabricated at three different scale factors (i.e., full-scale, half-scale, and one-fifth scale) to support laboratory acoustic testing. The panel configurations include single-degree-of-freedom (SDOF) perforated sandwich panels, SDOF linear (wire mesh) liners, and double-degree-of-freedom (DDOF) linear acoustic panels.Yu, J. and Kwan, H. W. and Echternach, D. K. and Kraft, R. E. and Syed, A. A.Langley Research CenterAIRCRAFT NOISE; ACOUSTIC PROPERTIES; SCALE MODELS; COST REDUCTION; FLOW RESISTANCE; GRAZING FLOW; IMPEDANCE MEASUREMENT; WIRE CLOTH; SANDWICH STRUCTURES; MINIATURIZATION; DEGREES OF FREEDOM; DUCTS...
Download or read book Acoustic Treatment Design Scaling Methods Volume 1 Overview Results and Recommendations written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-15 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scale model fan rigs that simulate new generation ultra-high-bypass engines at about 1/5-scale are achieving increased importance as development vehicles for the design of low-noise aircraft engines. Testing at small scale allows the tests to be performed in existing anechoic wind tunnels, which provides an accurate simulation of the important effects of aircraft forward motion on the noise generation. The ability to design, build, and test miniaturized acoustic treatment panels on scale model fan rigs representative of the fullscale engine provides not only a cost-savings, but an opportunity to optimize the treatment by allowing tests of different designs. The primary objective of this study was to develop methods that will allow scale model fan rigs to be successfully used as acoustic treatment design tools. The study focuses on finding methods to extend the upper limit of the frequency range of impedance prediction models and acoustic impedance measurement methods for subscale treatment liner designs, and confirm the predictions by correlation with measured data. This phase of the program had as a goal doubling the upper limit of impedance measurement from 6 kHz to 12 kHz. The program utilizes combined analytical and experimental methods to achieve the objectives. Kraft, R. E. and Yu, J. Glenn Research Center; Langley Research Center NASA/CR-1999-209120/VOL1, NAS 1.26:209120/VOL1
Download or read book Acoustic Analyses Using Matlab and Ansys written by Carl Q. Howard and published by CRC Press. This book was released on 2014-12-18 with total page 711 pages. Available in PDF, EPUB and Kindle. Book excerpt: Techniques and Tools for Solving Acoustics Problems This is the first book of its kind that describes the use of ANSYS® finite element analysis (FEA) software, and MATLAB® engineering programming software to solve acoustic problems. It covers simple text book problems, such as determining the natural frequencies of a duct, to progressively more complex problems that can only be solved using FEA software, such as acoustic absorption and fluid-structure-interaction. It also presents benchmark cases that can be used as starting points for analysis. There are practical hints too for using ANSYS software. The material describes how to solve numerous problems theoretically, and how to obtain solutions from the theory using MATLAB engineering software, as well as analyzing the same problem using ANSYS Workbench and ANSYS Mechanical APDL. Developed for the Practicing Engineer Free downloads on http://www.mecheng.adelaide.edu.au/avc/software, including MATLAB source code, ANSYS APDL models, and ANSYS Workbench models Includes readers’ techniques and tips for new and experienced users of ANSYS software Identifies bugs and deficiencies to help practitioners avoid making mistakes Acoustic Analyses Using MATLAB® and ANSYS® can be used as a textbook for graduate students in acoustics, vibration, and related areas in engineering; undergraduates in mechanical and electrical engineering; and as an authoritative reference for industry professionals.
Download or read book International Digital Imaging Correlation Society written by Michael Sutton and published by Springer. This book was released on 2017-03-30 with total page 257 pages. Available in PDF, EPUB and Kindle. Book excerpt: This collection represents a single volume of technical papers presented at the Annual International DIC Society Conference and SEM Fall Conference organized by the Society for Experimental Mechanics and Sandia National Laboratories and held in Philadelphia, PA, November 7-10, 2016. The volume presents early findings from experimental, standards development and various other investigations concerning digital image correlation - an important area within Experimental Mechanics. The area of Digital Image Correlation has been an integral track within the SEM Annual Conference spearheaded by Professor Michael Sutton from the University of South Carolina. In 2016, the SEM and Sandia joined their collaborative strengths to launch a standing fall meeting focusing specifically on developments in the area of Digital Image Correlation. The contributed papers within this volume span numerous technical aspects of DIC including standards development for the industry.
Download or read book Elastodynamics written by A.C. Eringen and published by Рипол Классик. This book was released on 1974 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the inception of the theory of elasticity with Navier A821) and Cauchy A828), the dynamical problems of elasticity and the subject of wave propagations in elastic solids have been under intense study by a large number of workers. In fact the literature is so extensive that any desire to write accounts on the subject immediately induces discouragement on the part of a prospective author. For it is impossible to do justice to all aspects of this wide field in any one- or two-volume treatise. Perhaps, partially, it is this concern that kept this important field barren of books for nearly two centuries.
Download or read book The Physics of Musical Instruments written by Neville H. Fletcher and published by Springer Science & Business Media. This book was released on 2013-11-09 with total page 763 pages. Available in PDF, EPUB and Kindle. Book excerpt: While the history of musical instruments is nearly as old as civilisation itself, the science of acoustics is quite recent. By understanding the physical basis of how instruments are used to make music, one hopes ultimately to be able to give physical criteria to distinguish a fine instrument from a mediocre one. At that point science may be able to come to the aid of art in improving the design and performance of musical instruments. As yet, many of the subtleties in musical sounds of which instrument makers and musicians are aware remain beyond the reach of modern acoustic measurements. This book describes the results of such acoustical investigations - fascinating intellectual and practical exercises. Addressed to readers with a reasonable grasp of physics who are not put off by a little mathematics, this book discusses most of the traditional instruments currently in use in Western music. A guide for all who have an interest in music and how it is produced, as well as serving as a comprehensive reference for those undertaking research in the field.
Download or read book Foundations of Engineering Acoustics written by Frank J. Fahy and published by Elsevier. This book was released on 2000-09-12 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt: Foundations of Engineering Acoustics takes the reader on a journey from a qualitative introduction to the physical nature of sound, explained in terms of common experience, to mathematical models and analytical results which underlie the techniques applied by the engineering industry to improve the acoustic performance of their products. The book is distinguished by extensive descriptions and explanations of audio-frequency acoustic phenomena and their relevance to engineering, supported by a wealth of diagrams, and by a guide for teachers of tried and tested class demonstrations and laboratory-based experiments. Foundations of Engineering Acoustics is a textbook suitable for both senior undergraduate and postgraduate courses in mechanical, aerospace, marine, and possibly electrical and civil engineering schools at universities. It will be a valuable reference for academic teachers and researchers and will also assist Industrial Acoustic Group staff and Consultants. Comprehensive and up-to-date: broad coverage, many illustrations, questions, elaborated answers, references and a bibliography Introductory chapter on the importance of sound in technology and the role of the engineering acoustician Deals with the fundamental concepts, principles, theories and forms of mathematical representation, rather than methodology Frequent reference to practical applications and contemporary technology Emphasizes qualitative, physical introductions to each principal as an entrée to mathematical analysis for the less theoretically oriented readers and courses Provides a 'cook book' of demonstrations and laboratory-based experiments for teachers Useful for discussing acoustical problems with non-expert clients/managers because the descriptive sections are couched in largely non-technical language and any jargon is explained Draws on the vast pedagogic experience of the writer
Download or read book Acoustic Waves in Periodic Structures Metamaterials and Porous Media written by Noé Jiménez and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book delivers a comprehensive and up-to-date treatment of practical applications of metamaterials, structured media, and conventional porous materials. With increasing levels of urbanization, a growing demand for motorized transport, and inefficient urban planning, environmental noise exposure is rapidly becoming a pressing societal and health concern. Phononic and sonic crystals, acoustic metamaterials, and metasurfaces can revolutionize noise and vibration control and, in many cases, replace traditional porous materials for these applications. In this collection of contributed chapters, a group of international researchers reviews the essentials of acoustic wave propagation in metamaterials and porous absorbers with viscothermal losses, as well as the most recent advances in the design of acoustic metamaterial absorbers. The book features a detailed theoretical introduction describing commonly used modelling techniques such as plane wave expansion, multiple scattering theory, and the transfer matrix method. The following chapters give a detailed consideration of acoustic wave propagation in viscothermal fluids and porous media, and the extension of this theory to non-local models for fluid saturated metamaterials, along with a description of the relevant numerical methods. Finally, the book reviews a range of practical industrial applications, making it especially attractive as a white book targeted at the building, automotive, and aeronautic industries.
Download or read book The Science and Applications of Acoustics written by Daniel R. Raichel and published by Springer Science & Business Media. This book was released on 2006-01-04 with total page 664 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook treats the broad range of modern acoustics from the basics of wave propagation in solids and fluids to applications such as noise control and cancellation, underwater acoustics, music and music synthesis, sonoluminescence, and medical diagnostics with ultrasound. The new edition is up-to-date and forward-looking in approach. Additional coverage of the opto-acoustics and sonoluminescence phenomena is included. New problems have been added throughout.
Download or read book Nondestructive Testing of Materials written by Roy Collins and published by IOS Press. This book was released on 1995 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reviews the current state of all types of electromagnetic testing techniques and considers the implications of innovations for future inspection practice both in Europe and Japan.This volume provides researchers with an overview of exchanges on the subjects of ACPD and ACFM from both Japanese and continental perspectives. For instance: the Japanese project of applied electromagnetic theory to inspect nuclear power plants and the theory of signal inversion for flaw identification. Topics covered are: - Inversion, imaging and flaw reconstruction - Advanced signal processing - Artificial intelligence and neural networks - Modelling, simulation and benchmark problems - Reliability of inspections, new techniques and novel sensors - Automation of data acquisition and processing The work covers a wide range of disciplines and will therefore serve a large number of researchers of electromagnetic theory for the next millenium.
Download or read book Sonochemistry and Sonoluminescence written by L.A. Crum and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sonochemistry is studied primarily by chemists and sonoluminescence mainly by physicists, but a single physical phenomenon - acoustic cavitation - unites the two areas. The physics of cavitation bubble collapse, is relatively well understood by acoustical physicists but remains practically unknown to the chemists. By contrast, the chemistry that gives rise to electromagnetic emissions and the acceleration of chemical reactions is familiar to chemists, but practically unknown to acoustical physicists. It is just this knowledge gap that the present volume addresses. The first section of the book addresses the fundamentals of cavitation, leading to a more extensive discussion of the fundamentals of cavitation bubble dynamics in section two. A section on single bubble sonoluminescence follows. The two following sections address the new scientific discipline of sonochemistry, and the volume concludes with a section giving detailed descriptions of the applications of sonochemistry. The mixture of tutorial lectures and detailed research articles means that the book can serve as an introduction as well as a comprehensive and detailed review of these two interesting and topical subjects.
Download or read book Rhythms of the Brain written by G. Buzsáki and published by Oxford University Press. This book was released on 2011 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies of mechanisms in the brain that allow complicated things to happen in a coordinated fashion have produced some of the most spectacular discoveries in neuroscience. This book provides eloquent support for the idea that spontaneous neuron activity, far from being mere noise, is actually the source of our cognitive abilities. It takes a fresh look at the coevolution of structure and function in the mammalian brain, illustrating how self-emerged oscillatory timing is the brain's fundamental organizer of neuronal information. The small-world-like connectivity of the cerebral cortex allows for global computation on multiple spatial and temporal scales. The perpetual interactions among the multiple network oscillators keep cortical systems in a highly sensitive "metastable" state and provide energy-efficient synchronizing mechanisms via weak links. In a sequence of "cycles," György Buzsáki guides the reader from the physics of oscillations through neuronal assembly organization to complex cognitive processing and memory storage. His clear, fluid writing-accessible to any reader with some scientific knowledge-is supplemented by extensive footnotes and references that make it just as gratifying and instructive a read for the specialist. The coherent view of a single author who has been at the forefront of research in this exciting field, this volume is essential reading for anyone interested in our rapidly evolving understanding of the brain.
