Wind Resource Characteristics and Energy Yield
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CHAPTER 20 Wind Turbine Noise Measurements and Abatement
CHAPTER 20 Wind turbine noise measurements and abatement methods Panagiota Pantazopoulou BRE, Watford, UK. This chapter presents an overview of the types, the measurements and the potential acoustic solutions for the noise emitted from wind turbines. It describes the fre- quency and the acoustic signature of the sound waves generated by the rotating blades and explains how they propagate in the atmosphere. In addition, the avail- able noise measurement techniques are being presented with special focus on the technical challenges that may occur in the measurement process. Finally, a discus- sion on the noise treatment methods from wind turbines referring to a range of the existing abatement methods is being presented. 1 Introduction Wind turbines generate two types of noise: aerodynamic and mechanical. A tur- bine’s sound power is the combined power of both. Aerodynamic noise is gener- ated by the blades passing through the air. The power of aerodynamic noise is related to the ratio of the blade tip speed to wind speed. The mechanical noise is associated with the relevant motion between the various parts inside the nacelle. The compartments move or rotate in order to convert kinetic energy to electricity with the expense of generating sound waves and vibration which is transmitted through the structural parts of the turbine. Depending on the turbine model and the wind speed, the aerodynamic noise may seem like buzzing, whooshing, pulsing, and even sizzling. Downwind tur- bines with their blades downwind of the tower cause impulsive noise which can travel far and become very annoying for people. The low frequency noise gener- ated from a wind turbine is primarily the result of the interaction of the aerody- namic lift on the blades and the atmospheric turbulence in the wind. -
Noise Barriers
INDOT’s Goal for Noise Reduction What is Noise? INDOT’s goal for substantial noise Noise is defined as unwanted sound and can come from man-made and natural 2,000 vehicles per hour sounds twice as loud (+10 dB(A)) reduction is to provide at least a 7 sources. Sound levels are measured in decibels (dB) and typically range from 40 as 200 vehicles per hour. dB(A) reduction for first-row receivers to 100 dB. in the year the barrier is constructed. However, conflicts with adjacent Because human hearing is limited in detecting very high and low frequencies, properties may make it impossible to “A-weighting” is commonly applied to sound levels to better characterize their achieve substantial noise reduction at effects on humans. A-weighted sound levels are expressed as dB(A). all impacted receptors. Therefore, the noise reduction design goal for Indiana is 7 dB(A) for a majority (greater than Common Outdoor Common Indoor Traffic at 65 MPH sounds twice as loud (+10 dB(A)) Noise Levels as traffic at 30 MPH. 50 percent) of the first-row receivers. Noise Levels Noise Levels Decibels, dB(A) 110 Rock Band Highway Traffic Noise Barriers: Jet Flyover at 1150ft (350m) 105 What Causes Traffic Noise? 100 Inside Subway Train (NY) The level of highway traffic noise depends on three factors: • Can reduce the loudness of traffic noise by as much Gas Lawn Mower at 3ft (1m) 95 • Volume of traffic as one-half Diesel Truck at 50ft (15m) 90 Food Blender at 3ft (1m) • Do not completely block all traffic noise 85 • Speed of traffic Noise Barriers 80 Garbage Disposal at 3ft (1m) • Can be effective regardless of the material used • Number of multi-axle vehicles 75 Shouting at 10ft (3m) • Must be tall and long with no openings Gas Lawn Mower at 100ft (30m) As any of these factors increase, noise levels increase. -
Active Noise Systems for Reducing Outdoor Noise
ACTIVE NOISE SYSTEMS FOR REDUCING OUTDOOR NOISE Biagini Massimiliano, Borchi Francesco, Carfagni Monica, Fibucchi Leonardo, and Lapini Alessandro Dipartimento di Ingegneria Industriale, Università di Firenze, via Santa Marta, 3 - I-50139 , Firenze, Italy email: [email protected] Argenti Fabrizio Dipartimento di Ingegneria dell’Informazione, Università di Firenze, via Santa Marta, 3 - I-50139 , Firenze, Italy An ANC system prototype designed for stationary noise control linked to traditional noise barriers was initially developed by authors in the past years. The encouraging results initially obtained have shown that ANC systems are feasible and should be further investigated to improve their performances. Nevertheless, FXLMS algorithm, considered in the first prototype architecture, is known to be affected by convergence problems that generally arise when a system fails to properly identify the noise to be cancelled; this process may (and often does) yield an instable system, where the control algorithm tries to catch-up its own sound, increasing the overall sound pressure level on the targets as in “avalanche” effect, potentially leading to damage fragile instrumentation. Hence, instability is unacceptable in practical applications and must be avoided or prevented. With this respect, in this manuscript some more robust alternative ANC algorithms have been investigated and experimentally verified. Keywords: active noise control, stability. 1. Introduction Active noise control (ANC) techniques are nowadays becoming more and more refined and reached a high level of maturity that allowed integration in modern acoustic devices, mainly targeted to hearing aids, headphones and propagation of noise in ducts [1, 2]. Only in recent years applications considering open field scenarios have been developed in practice (open spaces, ambient noise prop- agation [3, 4]), being such situations affected by weather phenomena, randomly moving sources and, circumstantially, time-varying emission spectrum. -
Atmospheric Effects on Traffic Noise Propagation
TRANSPORTATION RESEARCH RECORD 1255 59 Atmospheric Effects on Traffic Noise Propagation ROGER L. WAYSON AND WILLIAM BOWLBY Atmospheric effects on traffic noise propagation have largely L 0 sound level at a reference distance, been ignored during measurements and modeling, even though Ageo attenuation due to geometric spreading, it has generally been accepted that the effects may produce large Ab insertion loss due to diffraction, changes in receiver noise levels. Measurement of traffic noise at L, level increases due to reflection, and multiple locations concurrently with measurement of meteoro Ac attenuation due to ground characteristics and envi logical data is described. Statistical methods were used to evaluate the data. Atmospheric effects on traffic noise levels were shown ronmental effects. to be significant, even at very short distances; parallel components It should be noted that all levels in dB in this paper are of the wind (which are usually ignored) were important at second 2 row receivers; turbulent scattering increased noise levels near the referenced to 2 x 10-s N/m • ground more than refractive ray bending for short-distance prop The last term on the right side of Equation 1, A,, consists agation; and temperature lapse rates were not as important as of three parameters: ground attenuation, attenuation due to wind shear very near the highway. A statistical model was devel atmospheric absorption, and attenuation due to atmospheric oped to predict excess attenuations due to atmospheric effects. refraction. (2) Outdoor noise propagation has been studied since the time of the Greek philosopher Chrysippus (240 B. C.). Modern where prediction models have become accurate, and the advent of computers has increased the capabilities of models. -
Sound, Noise and Vibration an Explanation
Sound, Noise and Vibration An explanation Rupert Thornely-Taylor P5 (1) HOL/10002/0002 Outline of Presentation • What sound is - sources, and ways in which is it transmitted from source to receiver. • What vibration is - sources, and ways in which is it transmitted from source to receiver. • Human perception of sound and vibration. • Measurement scales and indices. • Assessment approaches - relationship between noise and vibration and human response to them. • Ways in which noise and vibration and their effects can be reduced. • Government policy regarding assessment and decision making. • HS2's application of government policy. P5 (2) HOL/10002/0003 Scope of sound and vibration issues SURFACE OPERATION - RAILWAY SURFACE OPERATION - FIXED PLANT UNDERGROUND OPERATION SURFACE CONSTRUCTION TUNNEL CONSTRUCTION P5 (3) HOL/10002/0004 Basics – what sound is • Sound is air oscillation that is propagated by wave motion at frequencies between 20 cycles/per second (Hertz, abbreviated Hz) and 20,000 cycles/second (20kHz). • Sound decays with distance – it spreads out, is reduced (attenuated) by soft ground surfaces and by intervening obstacles. • Sound is measured in frequency – weighted decibels (dBA) approximating the response of the human ear. • Noise is unwanted sound, which is difficult to measure due to the complexity of the human ear. P5 (4) HOL/10002/0005 Basics – what vibration is • Vibration is oscillation of solids that can be propagated through wave motion. • Vibration in soil decays with distance and is also attenuated by energy absorption in the soil and by obstacles and discontinuities. • Vibration is mainly of interest in the frequency range 0.5Hz to 250Hz and can give rise to audible sound which is then measured in decibels. -
Industrial Aerodynamics
INDUSTRIAL AERODYNAMICS Unit I Wind Energy Collectors INTRODUCTION Air Movement Wind Air Current Circulation The horizontal movement of air along the earth’s surface is called a Wind. The vertical movement of the air is known as an air current. Winds and air current together comprise a system of circulation in the atmosphere. TYPES OF WINDS On the earth’s surface, certain winds blow constantly in a particular direction throughout the year. These are known as the ‘Prevailing Winds’. They are also called the Permanent or the Planetary Winds. Certain winds blow in one direction in one season and in the opposite direction in another. They are known as Periodic Winds. Then, there are Local Winds in different parts of the world. 1. Planetary Winds: There are three main planetary winds that constantly blow in the same direction all around the world. They are also called prevailing or permanent winds. 1.Trade Winds: Blow from the subtropical high pressure belt towards the Equator. They are called the north-east trades in the northern hemisphere and south-east trades in the southern hemisphere. 2.Westerly winds: Blow from the same subtropical high pressure belts, towards 60˚ S and 60˚ N latitude. They are called the sought Westerly wind sin the northern hemisphere and North Westerly winds in the southern hemispheres. 3.Polar Winds Blow from the polar high pressure to the sub polar low pressure area. In the northern hemisphere, their direction is from the north-east. In the southern hemisphere, they blow from the south-east. 2. Periodic Winds These winds are known to blow for a certain time in a certain direction - it may be for a part of a day or a particular season of the year. -
Small Lightweight Aircraft Navigation in the Presence of Wind Cornel-Alexandru Brezoescu
Small lightweight aircraft navigation in the presence of wind Cornel-Alexandru Brezoescu To cite this version: Cornel-Alexandru Brezoescu. Small lightweight aircraft navigation in the presence of wind. Other. Université de Technologie de Compiègne, 2013. English. NNT : 2013COMP2105. tel-01060415 HAL Id: tel-01060415 https://tel.archives-ouvertes.fr/tel-01060415 Submitted on 3 Sep 2014 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Par Cornel-Alexandru BREZOESCU Navigation d’un avion miniature de surveillance aérienne en présence de vent Thèse présentée pour l’obtention du grade de Docteur de l’UTC Soutenue le 28 octobre 2013 Spécialité : Laboratoire HEUDIASYC D2105 Navigation d'un avion miniature de surveillance a´erienneen pr´esencede vent Student: BREZOESCU Cornel Alexandru PHD advisors : LOZANO Rogelio CASTILLO Pedro i ii Contents 1 Introduction 1 1.1 Motivation and objectives . .1 1.2 Challenges . .2 1.3 Approach . .3 1.4 Thesis outline . .4 2 Modeling for control 5 2.1 Basic principles of flight . .5 2.1.1 The forces of flight . .6 2.1.2 Parts of an airplane . .7 2.1.3 Misleading lift theories . 10 2.1.4 Lift generated by airflow deflection . -
Noise Assessment Activities
Noise assessment activities Interesting stories in Europe ETC/ACM Technical Paper 2015/6 April 2016 Gabriela Sousa Santos, Núria Blanes, Peter de Smet, Cristina Guerreiro, Colin Nugent The European Topic Centre on Air Pollution and Climate Change Mitigation (ETC/ACM) is a consortium of European institutes under contract of the European Environment Agency RIVM Aether CHMI CSIC EMISIA INERIS NILU ÖKO-Institut ÖKO-Recherche PBL UAB UBA-V VITO 4Sfera Front page picture: Composite that includes: photo of a street in Berlin redesigned with markings on the asphalt (from SSU, 2014); view of a noise barrier in Alverna (The Netherlands)(from http://www.eea.europa.eu/highlights/cutting-noise-with-quiet-asphalt), a page of the website http://rumeur.bruitparif.fr for informing the public about environmental noise in the region of Paris. Author affiliation: Gabriela Sousa Santos, Cristina Guerreiro, Norwegian Institute for Air Research, NILU, NO Núria Blanes, Universitat Autònoma de Barcelona, UAB, ES Peter de Smet, National Institute for Public Health and the Environment, RIVM, NL Colin Nugent, European Environment Agency, EEA, DK DISCLAIMER This ETC/ACM Technical Paper has not been subjected to European Environment Agency (EEA) member country review. It does not represent the formal views of the EEA. © ETC/ACM, 2016. ETC/ACM Technical Paper 2015/6 European Topic Centre on Air Pollution and Climate Change Mitigation PO Box 1 3720 BA Bilthoven The Netherlands Phone +31 30 2748562 Fax +31 30 2744433 Email [email protected] Website http://acm.eionet.europa.eu/ 2 ETC/ACM Technical Paper 2015/6 Contents 1 Introduction ...................................................................................................... 5 2 Noise Action Plans ......................................................................................... -
Overcoming Communication Barriers, Noise & Physical Barriers
Overcoming Communication Barriers: Noise and Physical Barriers Noise is one of the most common barriers in communication. It is any persistent or random disturbance which reduces, obscures or confuses the clarity of a message. Physical barriers are closely related to noise as they can obstruct the communication transmission process. Types of noise There are many forms of noise barriers which can occur during the communication process. Some examples are: physical interruptions by people interruption by technology, e.g. ringing telephone, new email, instant message, new Tweets, social media updates external noise e.g. distracting activities going on nearby such as traffic noise outside the building or conversations taking place in or near the room distortions of sound leading to delivery of incomplete messages, e.g. not hearing full words or phrases internal noise – physiological (e.g. blocked up ears), or psychological (e.g. distracting thoughts) the inclusion (in written communication) of irrelevant material or unsystematic approach to the subject matter Noise creates distortions of the message and prevents it from being understood the way it was intended. Comprehension usually deteriorates when there is loud, intrusive noise which interferes with the communication assimilation process. The level of noise is very important. Generally, quiet background noise can easily be filtered out, whereas loud or intrusive noise cannot. Dealing with noise To overcome the noise barrier, the source of the noise must first be established. This may not be easy as the noise may be coming from a conversation in an adjacent room, or from traffic passing by the window. Once the source has been identified, steps can be taken to overcome it. -
Guidelines for Selection and Approval of Noise Barrier Products Final Report
Guidelines for Selection and Approval of Noise Barrier Products Final Report Prepared for: National Cooperative Highway Research Program Project 25-25, Task 40 Prepared by: ICF International 33 Hayden Avenue Lexington, MA 02421 July 2008 The information contained in this report was prepared as part of NCHRP Project 25-25 Task 40, National Cooperative Highway Research Program, Transportation Research Board. Acknowledgement This study was conducted as part of National Cooperative Highway Research Program (NCHRP) Project 25-25, in cooperation with the American Association of State Highway and Transportation Officials (AASHTO) and the U.S. Department of Transportation. The report was prepared by David Ernst, Leiran Biton, Steven Reichenbacher, and Melissa Zgola of ICF International, and Cary Adkins of Harris Miller Miller & Hanson Inc. The project was managed by Christopher Hedges, NCHRP Senior Program Officer. Disclaimer The opinions and conclusions expressed or implied are those of the research agency that performed the research and are not necessarily those of the Transportation Research Board or its sponsors. This report has not been reviewed or accepted by the Transportation Research Board's Executive Committee or the Governing Board of the National Research Council. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by NCHRP, the Transportation Research Board or the National Research Council. i Abstract State departments of transportation (DOTs) have identified a need for guidance on noise barrier materials products. This study identified and reviewed literature relevant to noise barrier materials and products with respect to characteristics, testing, selection, and approval. -
Noise Barrier Design: Danish and Some European Examples
May 2010 Reprint Report: UCPRC-RP-2010-04 NNNoooiiissseee BBBaaarrrrrriiieeerrr DDDeeesssiiigggnnn::: DDDaaannniiissshhh aaannnddd SSSooommmeee EEEuuurrrooopppeeeaaannn EEExxxaaammmpppllleeesss Author: Hans Bendtsen, Danish Road Institute—Road Directorate This report is based on research performed by the Danish Road Institute-Road Directorate on behalf of the University of California Pavement Research Center for the California Department of Transportation, and is reprinted here in its original form. Work Conducted as Part of the “Supplementary Studies for Caltrans QPR Program” Contract PREPARED FOR: PREPARED BY: California Department of Transportation The Danish Road Institute— (Caltrans) Road Directorate and University of California Division of Research and Innovation Pavement Research Center Danish Road Institute DOCUMENT RETRIEVAL PAGE Reprint Report UCPRC-RP-2010-04 Title: Noise Barrier Design: Danish and Some European Examples Author: Hans Bendtsen Prepared for: FHWA No.: Date Work Submitted: Date: Caltrans CA101735D July 2009 May 2010 Contract/Subcontract Nos.: Status: Version No: Caltrans Contract: 65A0293 Final 1 UC DRI-DK: Subcontract 08-001779-01 Abstract: Noise barriers are widely used as an effective means to abate highway traffic noise. With public interest in eco-friendly and aesthetic designs for noise barriers growing, highway agencies are exerting greater efforts to provide the public with “green” noise barriers that are functionally sound as well as adaptive to the surrounding environment. This report presents a summary of green noise barrier design practices experienced by the Danish Road Institute (DRI-DK) and other European countries for the last two decades. Some example noise barrier designs are described with recommendations for more effective and innovative ones. The report contains a recommendation to use varied approaches in green noise barrier designs that are adapted to urban and rural settings. -
2017 Noise Requirements
DEPARTMENT OF TRANSPORTATION Noise Requirements for MnDOT and other Type I Federal-aid Projects Satisfies FHWA requirements outlined in 23 CFR 772 Effective Date: July 10, 2017 Website address where additional information can be found or inquiries sent: http://www.dot.state.mn. u /environment/noise/index.html "To request this document in an alternative format, contact Janet Miller at 651-366-4720 or 1-800-657-3774 (Greater Minnesota); 711or1-800-627-3529 (Minnesota Relay). You may also send an e-mail to [email protected]. (Please request at least one week in advance). MnDOT Noise Requirements: Effective Date July 10, 2017 This document contains the Minnesota Department of Transportation Noise Requirements (hereafter referred to as 'REQUIREMENTS') which describes the implementation of the requirements set forth by the Federal Highway Administration Title 23 Code of Federal Regulations Part 772: Procedures for Abatement of Highway Traffic Noise and Construction Noise. These REQUIREMENTS also describe the implementation of the requirements set forth by Minnesota Statute 116.07 Subd.2a: Exemptions from standards, and Minnesota Rule 7030: Noise Pollution Control. These REQUIREMENTS were developed by the Minnesota Department of Transportation and reviewed and approved with by the Federal Highway Administration. C,- 2.8-{7 Charles A. Zelle, Commissioner Date Minnesota Department of Transportation toJ;.11/11 Arlene Kocher, Divi lronAdmini ~ rator Date I Minnesota Division Federal Highway Administration MnDOT Noise Requirements: Effective