| 1. |
- Aihara, Aya, 1989-, et al.
(författare)
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Aeroacoustic noise prediction of a vertical axis wind turbine using large eddy simulation
- 2021
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Ingår i: International Journal of Aeroacoustics. - : SAGE Publications. - 1475-472X .- 2048-4003. ; 20:8, s. 959-978
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the numerical prediction for the aerodynamic noise of the vertical axis wind turbine using large eddy simulation and the acoustic analogy. Low noise designs are required especially in residential areas, and sound level generated by the wind turbine is therefore important to estimate. In this paper, the incompressible flow field around the 12 kW straight-bladed vertical axis wind turbine with the rotor diameter of 6.5 m is solved, and the sound propagation is calculated based on the Ffowcs Williams and Hawkings acoustic analogy. The sound pressure for the turbine operating at high tip speed ratio is predicted, and it is validated by comparing with measurement. The measured spectra of the sound pressure observed at several azimuth angles show the broadband characteristics, and the prediction is able to reproduce the shape of these spectra. While previous works studying small-scaled vertical axis wind turbines found that the thickness noise is the dominant sound source, the loading noise can be considered to be a main contribution to the total sound for this turbine. The simulation also indicates that the received noise level is higher when the blade moves in the downwind than in the upwind side.
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| 2. |
- Alvarsson, Jesper, et al.
(författare)
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Buller i Silverdal 2016
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Forskning visar att buller orsakar ohälsa för många medborgare både i Europa generellt, och i Sverige. De två viktigaste negativa hälsoeffekterna av buller är försämrad sömn och bullerstörning. Trafikbuller är den främsta orsaken till dessa effekter.I denna studie användes enkäter samt data från bullerkartor för att undersöka bullerstörning från trafik. Av de 1168 personerna i urvalet deltog 678 personer. Deltagarna svarade på 39 frågor rörande: buller, hälsa, rekreationsbeteende, luftkvalitéupplevelse samt demografi.Studiens första syfte var att undersöka bullerstörning från vägtrafik och spårtrafik, hos boende i Silverdal. Resultatet visade att de boende i Silverdal är mer störda av buller än genomsnittet i Sverige, men även jämfört med de beräknade störningsnivåerna från bullerkartorna. Faktorerna som starkast påverkade störning från vägtrafik var: upplevda vibrationer, den upplevda luftkvalitén hemma, utbildningsnivå, om sovrumsfönstret vette mot en lokalgata samt attityd till vägtrafik. Motsvarande faktorer för spårtrafik var: upplevda vibrationer, sovrumsfönster mot spår samt utbildningsnivå.Studiens andra syfte undersökte upplevelse av rekreationsmöjligheter och rekreationsbeteende. Resultatet visade att majoriteten av deltagarna upplever mycket bra möjligheter till rekreation. Områden, nära hemmet, med natur samt med lägre nivåer av bullernivåer, var mest besökta.Studiens tredje syfte var att undersöka hur boende i Silverdal upplevde luftkvalitén. Resultatet visar att utomhusluften är det som upplevs mest problematiskt, medan färre upplever inomhusluften som dålig.Studien visar att många boende i Silverdal är störda av buller, både jämfört med nationella undersökningar, men även i relation till den beräknade bullerstörningsnivån från bullerkartor. Rekreationsmiljön i området upplevs som relativt god och lufkvalitén upplevs som ett relativt mindre problem jämfört med bullret. Utomhusmiljön är den miljö som upplevs som är mest problematiskt för boende. Bulleråtgärder utomhus längs bullerkällornas sträckning rekommenderas, dels eftersom de efterfrågas av de boende, del för att de minskar bullret både utomhus och inomhus.
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| 3. |
- Andersson, B. L., et al.
(författare)
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Assessment of sound propagation modelling from a wind turbine site at sea
- 2009
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Ingår i: 16th International Congress on Sound and Vibration 2009, ICSV 2009. - 9781615677368 ; , s. 896-903
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Konferensbidrag (refereegranskat)abstract
- We present results from numerical modelling of sound propagation from Utgrunden lighthouse in Kalmarsund to a receiver at Hammarby on the island Ö land east of Sweden in the Baltic. The propagation distances from source to shore and from shore to receiver are ca 9 km and 0.7 km, respectively. Our purpose is to assess prediction of atmospheric sound propagation by methods that use detailed knowledge of the local geometry and meteorology, by comparing model predictions of the transmission loss with experimental data. The experimental data, collected several times daily during a one-week campaign in June 2005, consist of (i) data on the transmission loss of narrow band signals from controlled sources with frequencies 80 Hz, 200 Hz and 400 Hz, (ii) atmospheric parameters as function of height from radio-soundings and balloon-tracking at the receiver location and (iii) atmospheric parameters from sensors mounted on a meteorological mast at the source location. Model-predicted soundfields were computed once per hour during the one-week period, with a windfield composed of a laminar field determined from data at the receiver, superimposed by a turbulent field determined by data from the meteorological mast. Comparisons of the experimentally observed transmission loss with predictions by the Green's Function Parabolic Equation (GFPE) method by Gilbert and Di are presented. A reasonably good fit of the model predicted transmission loss as function of time to experimental data at all frequencies is observed.
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| 4. |
- Bengtsson Ryberg, Johanna, et al.
(författare)
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The Effects of Wind Power on Human Interests : A Synthesis
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- PrefaceThere is a great need for knowledge concerning the impacts of wind power on humans, landscapes, the marine environment, birds, bats and other mammals.Previous studies of these environmental impacts have lacked an overall view of the effects. This has led to deficiencies in the processes surrounding the establishment of new wind farms. Vindval is a knowledge programme undertaken as a collaboration between the Swedish Energy Agency and the Swedish Environmental Protection Agency. Its aim is to gather and communicate scientific knowledge about the impacts of wind power on people and the natural environment. The programme continues until 2013.Vindval comprises some 30 individual research projects, together with four synthesis projects. Syntheses are prepared by experts, who compile and assess overall research results and experience regarding the effects of wind power in four different areas – humans, birds/bats, marine life and terrestrial mammals.The results of this research and synthesis work will provide a basis for environmental impact assessments and for the planning and permitting processes associated with wind power installations. Vindval requires high standards in the review and approval of research proposals, in order to ensure high-quality reports. The same high standards apply to the reporting, approval and publication of research results from the projects.This report was written by Johanna Bengtsson Ryberg, Gösta Bluhm, Karl Bolin, Bosse Bodén, Kristina Ek, Karin Hammarlund, Marianne Henningsson, Inga-Lena Hannukka, Carina Johansson, Sofia Jönsson, Sanna Mels, Tom Mels, Mats Nilsson, Erik Skärbäck, Patrik Söderholm, Åsa Waldo, Ingegärd Widerström, Niklas Åkerman.This report is a translation of the previous report in Swedish “Vindkraftens påverkan på människors intressen” (Naturvårdsverket report no 6497). Translated by Sofia Jönsson.The contents of the report are the responsibility of the authors.
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| 5. |
- Bolin, Karl, et al.
(författare)
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Air-borne sound generated by sea waves
- 2010
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Ingår i: Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 0001-4966 .- 1520-8524. ; 127:5, s. 2771-2779
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes a semi-empiric model and measurements of air-borne sound generated by breaking sea waves. Measurements have been performed at the Baltic Sea. Shores with different slopes and sediment types have been investigated. Results showed that the sound pressure level increased from 60 dB at 0.4 m wave height to 78 dB at 2.0 m wave height. The 1/3 octave spectrum was dependent on the surf type. A scaling model based on the dissipated wave power and a surf similarity parameter is proposed and compared to measurements. The predictions show satisfactory agreement to the measurements. (C) 2010 Acoustical Society of America. [DOI: 10.1121/1.3327815]
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| 6. |
- Bolin, Karl, 1977-, et al.
(författare)
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An investigation of the influence of the refractive shadow zone on wind turbine noise
- 2020
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Ingår i: Journal of the Acoustical Society of America. - : Acoustical Society of America. - 0001-4966 .- 1520-8524. ; 148:2, s. EL166-EL171
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Tidskriftsartikel (refereegranskat)abstract
- This article aims to investigate if the proportion of the rotor area of a wind turbine that is in the refractive shadow zone according to a ray tracing algorithm coupled to meteorological forecast data is correlated to sound levels and amplitude modulation. The acoustic station is situated 950 m from a wind farm in Northern Sweden and the measurement period is seven months. On average, 1.9 dBA lower sound levels are measured when the part of the rotor disk of the closest turbine is in the refractive shadow zone. A higher probability of amplitude modulations are observed when around half of the turbine rotor is within the refractive shadow zone compared to conditions with no shadow zone present.
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| 7. |
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| 8. |
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| 9. |
- Bolin, Karl, 1977-, et al.
(författare)
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Improved methods for source characterization on trains
- 2022
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Ingår i: Internoise 2022. - : The Institute of Noise Control Engineering of the USA, Inc..
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Konferensbidrag (refereegranskat)abstract
- One problem for railway noise predictions is to characterize noise from various auxiliary equipment, e.g., fans, compressors, transformers. The noise from such sources can be a dominating contribution under low-speed operation or stand still. To better handle this problem the EU-project TRANSIT investigates improved methods for acoustic source characterization. As a starting point it is assumed that an acoustic source is enclosed by a control surface. The surface is sub-divided into smaller areas and each area is assumed to act as an acoustic one-port coupled to all the other areas. The properties of each area can then be described by its volume flow and internal impedance. The resulting acoustic pressure at a receiving point, can finally be expressed as a product of the source volume flows and a matrix representing the acoustic installation effects (“source+radiation impedances”). To simplify the method one can assume uncorrelated sources and use an ISO procedure for sound power to determine the volume flows. The acoustic installation effects can be obtained using a monopole point source to measure or calculate the pressure at selected receiving positions.
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| 10. |
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