Download or read book Hybrid Active Passive Jet Engine Noise Suppression System written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-13 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: A novel adaptive segmented liner concept has been developed that employs active control elements to modify the in-duct sound field to enhance the tone-suppressing performance of passive liner elements. This could potentially allow engine designs that inherently produce more tone noise but less broadband noise, or could allow passive liner designs to more optimally address high frequency broadband noise. A proof-of-concept validation program was undertaken, consisting of the development of an adaptive segmented liner that would maximize attenuation of two radial modes in a circular or annular duct. The liner consisted of a leading active segment with dual annuli of axially spaced active Helmholtz resonators, followed by an optimized passive liner and then an array of sensing microphones. Three successively complex versions of the adaptive liner were constructed and their performances tested relative to the performance of optimized uniform passive and segmented passive liners. The salient results of the tests were: The adaptive segmented liner performed well in a high flow speed model fan inlet environment, was successfully scaled to a high sound frequency and successfully attenuated three radial modes using sensor and active resonator arrays that were designed for a two mode, lower frequency environment. Parente, C. A. and Arcas, N. and Walker, B. E. and Hersh, A. S. and Rice, E. J. Glenn Research Center NCC3-379; RTOP 538-03-11

Download or read book Hybrid Active Passive Jet Engine Noise Suppression System written by and published by . This book was released on 1999 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook of Noise and Vibration Control written by Malcolm J. Crocker and published by John Wiley & Sons. This book was released on 2007-10-05 with total page 1594 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two of the most acclaimed reference works in the area of acoustics in recent years have been our Encyclopedia of Acoustics, 4 Volume set and the Handbook of Acoustics spin-off. These works, edited by Malcolm Crocker, positioned Wiley as a major player in the acoustics reference market. With our recently published revision of Beranek & Ver's Noise and Vibration Control Engineering, Wiley is a highly respected name in the acoustics business. Crocker's new handbook covers an area of great importance to engineers and designers. Noise and vibration control is one largest areas of application of the acoustics topics covered in the successful encyclopedia and handbook. It is also an area that has been under-published in recent years. Crocker has positioned this reference to cover the gamut of topics while focusing more on the applications to industrial needs. In this way the book will become the best single source of need-to-know information for the professional markets.

Download or read book Comprehensive Investigation on Active Passive Hybrid Isolation and Tunable Dynamic Vibration Absorption written by Fei Wang and published by Springer. This book was released on 2018-12-17 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses efforts to control the low-frequency vibration transmission of typical power equipment and pipeline systems of ships, exploring the use of active and passive hybrid vibration isolation and adjustable dynamic vibration absorption technologies. It also proposes an adaptive feed-forward control strategy and studies a distributed feed-forward control hardware system. In addition, the book presents a three-way dynamic vibration absorption theory used to design a pipeline-system adjustable dynamic vibration absorber, which offers a number of advantages, such as compact structure, easy assembly and disassembly, low power consumption, excellent vibration control effect and wide frequency band adjustable ability, etc. This book is a valuable resource for researchers and engineers in the fields of noise and vibration control, active control systems, active vibration isolation and adaptive dynamic vibration absorption.

Download or read book Engineering Acoustics written by Malcolm J. Crocker and published by John Wiley & Sons. This book was released on 2021-01-11 with total page 784 pages. Available in PDF, EPUB and Kindle. Book excerpt: ENGINEERING ACOUSTICS NOISE AND VIBRATION CONTROL A masterful introduction to the theory of acoustics along with methods for the control of noise and vibration In Engineering Acoustics: Noise and Vibration Control, two experts in the field review the fundamentals of acoustics, noise, and vibration. The authors show how this theoretical work can be applied to real-world problems such as the control of noise and vibration in aircraft, automobiles and trucks, machinery, and road and rail vehicles. Engineering Acoustics: Noise and Vibration Control covers a wide range of topics. The sixteen chapters include the following: Human hearing and individual and community response to noise and vibration Noise and vibration instrumentation and measurements Interior and exterior noise of aircraft as well as road and rail vehicles Methods for the control of noise and vibration in industrial equipment and machinery Use of theoretical models in absorptive and reactive muffler and silencer designs Practical applications of finite element, boundary element and statistical energy analysis Sound intensity theory, measurements, and applications Noise and vibration control in buildings How to design air-conditioning systems to minimize noise and vibration Readers, whether students, professional engineers, or community planners, will find numerous worked examples throughout the book, and useful references at the end of each chapter to support supplemental reading on specific topics. There is a detailed index and a glossary of terms in acoustics, noise, and vibration.

Download or read book Technology for a Quieter America written by National Academy of Engineering and published by National Academies Press. This book was released on 2010-10-30 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: Exposure to noise at home, at work, while traveling, and during leisure activities is a fact of life for all Americans. At times noise can be loud enough to damage hearing, and at lower levels it can disrupt normal living, affect sleep patterns, affect our ability to concentrate at work, interfere with outdoor recreational activities, and, in some cases, interfere with communications and even cause accidents. Clearly, exposure to excessive noise can affect our quality of life. As the population of the United States and, indeed, the world increases and developing countries become more industrialized, problems of noise are likely to become more pervasive and lower the quality of life for everyone. Efforts to manage noise exposures, to design quieter buildings, products, equipment, and transportation vehicles, and to provide a regulatory environment that facilitates adequate, cost-effective, sustainable noise controls require our immediate attention. Technology for a Quieter America looks at the most commonly identified sources of noise, how they are characterized, and efforts that have been made to reduce noise emissions and experiences. The book also reviews the standards and regulations that govern noise levels and the federal, state, and local agencies that regulate noise for the benefit, safety, and wellness of society at large. In addition, it presents the cost-benefit trade-offs between efforts to mitigate noise and the improvements they achieve, information sources available to the public on the dimensions of noise problems and their mitigation, and the need to educate professionals who can deal with these issues. Noise emissions are an issue in industry, in communities, in buildings, and during leisure activities. As such, Technology for a Quieter America will appeal to a wide range of stakeholders: the engineering community; the public; government at the federal, state, and local levels; private industry; labor unions; and nonprofit organizations. Implementation of the recommendations in Technology for a Quieter America will result in reduction of the noise levels to which Americans are exposed and will improve the ability of American industry to compete in world markets paying increasing attention to the noise emissions of products.

Download or read book Noise Reduction Efforts for Special Operations C 130 Aircraft Using Active Synchrophaser Control written by and published by . This book was released on 1998 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aircraft noise often inhibits mission effectiveness. As a result, flight crews, ground maintenance personnel, and passengers suffer degraded voice communication, impaired performance, increased fatigue, and hearing loss. In an effort to reduce the level of noise both inside and outside of the aircraft, techniques have been developed that attempt to quiet the environment. The simplest approach uses passive noise reduction methods, including installing acoustic insulation and exhaust modifications, but these only provide limited success. A more complicated approach uses an active noise cancellation (ANC) system, which offers improved performance that can augment passive methods to significantly reduce both internal and external aircraft noise. ANC achieves noise reduction by creating an anti-noise, which is an equal and opposite acoustic wave that cancels the unwanted noise. This type of cancellation works well in smaller volumes, like headset ear cups. For larger volumes or environments, arrays of loudspeakers are needed, but are often ineffective due to their size and weight. Since the primary noise on multi-engine turboprop aircraft, such as the C-130, originates from the engine-propeller system, the noise from one engine-propeller can be tuned to provide a canceling acoustic wave to reduce the noise generated from another engine-propeller on the same aircraft. Because the levels of noise generated from each engine-propeller combination are similar under normal operating conditions, a means to adjust the propeller phasing to create a noise canceling effect is needed. For multi-engine propeller-driven aircraft, engine-propeller phase control is accomplished using an electromechanical device called a synchrophaser. To optimally control the phase angle relationships among the four engine propellers, a controllable or active synchrophaser system is needed. The synchrophaser system described in this paper is a joint effort between AFRL and AFSOC.

Download or read book Understanding Active Noise Cancellation written by Colin N. Hansen and published by CRC Press. This book was released on 2002-05-03 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding Active Noise Cancellation Provides a concise introduction to the fundamentals and applications of active control of vibration and sound for the non-expert. It is also a useful quick reference for the specialist engineer. The book emphasises the practical applications of technology, and complex control algorithms and structures are only discussed to the extent that they aid understanding. Extensive recommendations for further reading on the subject are provided, but the text will stand alone for those seeking an overview of the key issues: fundamentals, control systems, transducers, applications and possible future directions.

Download or read book Fan Noise Reduction An Overview written by Edmane Envia and published by . This book was released on 2001 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Jet Engine Test Cell Noise Reduction written by C. A. Kodres and published by . This book was released on 2000-08-01 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt: Passive methods for decreasing jet engine test cell noise emissions are evaluated and compared. Such methods have the dual advantages of low cost and simplicity. In addition, the effect on the aerothermal performance of the test cell is minimal. Sound pressure levels were measured in and around test facilities equipped with various devices to further reduce noise. The data were supplemented with parametric studies of noise reduction techniques conducted using a 1/20th scale physical model of the Navy's standard T-10 jet engine test cell. Methods that attack the noise problem from outside and methods that attack the problem from inside the test cell are assessed, including trees and other vegetation, acoustic walls, core busters, and modifications to the exhaust stack. Mounting screens in the path of the jet and increasing the height of the exhaust stack are found to be the most effective.

Download or read book Fundamental Study of Jet Noise Generation and Suppression written by W. C. Sperry and published by . This book was released on 1961 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Active Liner System for Jet Engine Exhaust Silencers Phase 1 written by and published by . This book was released on 1994 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the framework of the U.S. Air Force's Advanced Technology Active Noise Reduction Initiative - an experimental program was carried out to demonstrate the feasibility of a new concept of an Active Liner. Using a 1:4 scale model of a jet engine test cell augmenter 8 dB to 15 dB reduction of the low frequency (8 Hz to 80 Hz at full scale) was obtained by inserting one or two active liner segments into a typical lined augmenter. The topics covered in this report include: (1) problems caused by low frequency noise and their land use implications, (2) description of the active liner concept, (3) control strategies employed, (4) description of the model-scale augmenter including passive and active sections and the feedback control system, (5) experimental results, (6) full-scale ramifications and (7) risk assessment of full-scale implementation.

Download or read book Active and Passive Smart Structures and Integrated Systems 2007 written by Yuji Matsuzaki and published by SPIE-International Society for Optical Engineering. This book was released on 2007 with total page 728 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of SPIE present the original research papers presented at SPIE conferences and other high-quality conferences in the broad-ranging fields of optics and photonics. These books provide prompt access to the latest innovations in research and technology in their respective fields. Proceedings of SPIE are among the most cited references in patent literature.

Download or read book Active Control of Noise and Vibration written by Colin Hansen and published by CRC Press. This book was released on 2012-11-02 with total page 1564 pages. Available in PDF, EPUB and Kindle. Book excerpt: Integrating active control of both sound and vibration, this comprehensive two-volume set combines coverage of fundamental principles with the most recent theoretical and practical developments. The authors explain how to design and implement successful active control systems in practice and detail the pitfalls one must avoid to ensure a reliable and stable system. Extensively revised, updated, and expanded throughout, the second edition reflects the advances that have been made in algorithms, DSP hardware, and applications since the publication of the first edition.

Download or read book Active and Passive Smart Structures and Integrated Systems 2008 written by Mehdi Ahmadian and published by . This book was released on 2008 with total page 812 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of SPIE present the original research papers presented at SPIE conferences and other high-quality conferences in the broad-ranging fields of optics and photonics. These books provide prompt access to the latest innovations in research and technology in their respective fields. Proceedings of SPIE are among the most cited references in patent literature.

Download or read book Electroactive Polymer EAP Actuators as Artificial Muscles written by Yoseph Bar-Cohen and published by SPIE Press. This book was released on 2004 with total page 790 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covers the field of EAP with attention to all aspects and full infrastructure, including the available materials, analytical models, processing techniques, and characterization methods. This second edition covers advances in EAP in electric EAP, electroactive polymer gels, ionomeric polymer-metal composites, and carbon nanotube actuators.

Download or read book Noise and Vibration Control Engineering written by István L. Vér and published by John Wiley & Sons. This book was released on 2005-11-11 with total page 976 pages. Available in PDF, EPUB and Kindle. Book excerpt: Noise and Vibration Control Engineering: Principles and Applications, Second Edition is the updated revision of the classic reference containing the most important noise control design information in a single volume of manageable size. Specific content updates include completely revised material on noise and vibration standards, updated information on active noise/vibration control, and the applications of these topics to heating, ventilating, and air conditioning.