• Title/Summary/Keyword: local wind

Search Result 718, Processing Time 0.027 seconds

A neural network shelter model for small wind turbine siting near single obstacles

  • Brunskill, Andrew William;Lubitz, William David
    • Wind and Structures
    • /
    • v.15 no.1
    • /
    • pp.43-64
    • /
    • 2012
  • Many potential small wind turbine locations are near obstacles such as buildings and shelterbelts, which can have a significant, detrimental effect on the local wind climate. A neural network-based model has been developed which predicts mean wind speed and turbulence intensity at points in an obstacle's region of influence, relative to unsheltered conditions. The neural network was trained using measurements collected in the wakes of 18 scale building models exposed to a simulated rural atmospheric boundary layer in a wind tunnel. The model obstacles covered a range of heights, widths, depths, and roof pitches typical of rural buildings. A field experiment was conducted using three unique full scale obstacles to validate model predictions and wind tunnel measurements. The accuracy of the neural network model varies with the quantity predicted and position in the obstacle wake. In general, predictions of mean velocity deficit in the far wake region are most accurate. The overall estimated mean uncertainties associated with model predictions of normalized mean wind speed and turbulence intensity are 4.9% and 12.8%, respectively.

Performance Study of Wind Augmentation Device for Building-integrated Wind Power (건물 풍력발전을 위한 집풍장치 성능 연구)

  • Shin, Jae-Ryul;Park, Jae-Jeun;Kim, Han-Young;Kim, Dae-Young
    • The KSFM Journal of Fluid Machinery
    • /
    • v.15 no.4
    • /
    • pp.42-49
    • /
    • 2012
  • This study is performance estimation of wind augmentation device for BiWP(Building-integrated Wind Power) which recently attracts attention as a local power. various structures are installed on a rooftop of residential complex buildings. Changing a profile of these, we designed a configuration that is able to capture much air and increase exit velocity. To estimate wind augmented effect of this device, we compared numerical analysis results with wind tunnel test results. Results show that exit velocity is increased from 24% to 60% by wind augmented device on a rooftop of building.

Wind Resource Assessment of the Antarctic King Sejong Station by Computational Flow Analysis (남극 세종기지의 전산유동해석에 의한 풍력자원평가)

  • Kim, Seok-Woo;Kim, Hyun-Goo
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 2007.11a
    • /
    • pp.376-377
    • /
    • 2007
  • In accordance with Madrid and Kyoto Protocols, a 10kW wind turbine installed about 625m away from the King Sejong Station in the Antarctica has been in operation successfully. The current location of the wind turbine has different geographic surroundings from the previous candidate site considered in 2005 and that makes re-evaluation of wind resource at the current site including geographic effects necessary. Especially, strong wind flow derived by steep and complex terrain is dominant in the Antarctica so that computational flow analysis is required. The wind rose measured at the previous and current installation location are identical with strong meteorological correlation but prevailing directions of wind power density are different because of local wind acceleration due to complex terrain. Numerical analysis explains which effects brings this discordance between the two sites, and a design guideline required for additional wind turbine installation has been secured.

  • PDF

Wind-induced dynamic response of recessed balcony facades

  • Matthew J. Glanville;John D. Holmes
    • Wind and Structures
    • /
    • v.38 no.3
    • /
    • pp.193-202
    • /
    • 2024
  • Modern high-rise tower designs incorporating recessed balcony cavity spaces can be prone to high-frequency and narrow-band Rossiter aerodynamic excitations under glancing incident winds that can harmonize and compete with recessed balcony volume acoustic Helmholtz modes and facade elastic responses. Resulting resonant inertial wind loading to balcony facades responding to these excitations is additive to the peak design wind pressures currently allowed for in wind codes and can present as excessive facade vibrations and sub-audible throbbing in the serviceability range of wind speeds. This paper presents a methodology to determine Cavity Amplification Factors to account for façade resonant inertial wind loads resulting from balcony cavity aero-acoustic-elastic resonances by drawing upon field observations and the results of full-scale monitoring and model-scale wind tunnel tests. Recessed balcony cavities with single orifice type openings and located within curved façade tower geometries appear particularly prone. A Cavity Amplification Factor of 1.8 is calculated in one example representing almost a doubling of local façade design wind pressures. Balcony façade and tower design recommendations to mitigate wind induced aero-acoustic-elastic resonances are provided.

Wind tunnel study of wind structure at a mountainous bridge location

  • Yan, Lei;Guo, Zhen S.;Zhu, Le D.;Flay, Richard G.J.
    • Wind and Structures
    • /
    • v.23 no.3
    • /
    • pp.191-209
    • /
    • 2016
  • Wind tunnel tests of a 1/2200-scale mountainous terrain model have been carried out to investigate local wind characteristics at a bridge location in southeast Tibet, China. Flows at five key locations on the bridge at deck level were measured for 26 directions. It was observed that wind characteristics (including mean wind velocity and overall turbulence intensity) vary significantly depending on the approaching wind direction and measurement position. The wind inclination angle measured in the study fluctuated between $-18^{\circ}$ and $+16^{\circ}$ and the ratio of mean wind velocity to reference wind velocity was small when the wind inclination angles were large, especially for positive wind inclination angles. The design standard wind speed and the minimum critical wind speed for flutter rely on the wind inclination angle and should be determined from the results of such tests. The variation of wind speed with wind inclination angles should be of the asymmetry step type. The turbulence characteristics of the wind were found to be similar to real atmospheric flows.

Estimate of urban contributions to elevated ozone levels in downwind area of Seoul for local wind days (서울지역 국지풍일의 도심배출에 의한 풍하측 오존증가량 추정)

  • 오인보;김유근
    • Proceedings of the Korea Air Pollution Research Association Conference
    • /
    • 2002.11a
    • /
    • pp.157-158
    • /
    • 2002
  • 도시/국지규모에서의 풍하측 오존농도 상승은 도심 및 인근지역 배출원 환경과 함께 국지풍(local wind)에 의해 크게 좌우된다. 즉 도심배출에 의한 오존의 광화학 생성과 국지풍에 따른 단거리수송 및 국지적 축적 효과가 결부되어 풍하측 고농도가 나타나게 되는 것이다. 기존 여러 연구에서 도심의 경우 지속적인 NOx 배출의 영향으로 오존농도가 상승하지 못하는 반면 (NOx titration), 상대적으로 배출원이 적은 풍하측지역은 오존 및 전구물질의 수송과 축적을 통해 고농도가 나타남을 밝히고 있다. (중략)

  • PDF

Distribution of Wind Force Coefficients on the Three-span Arched House (아치형 3연동하우스의 풍력계수 분포에 관한 연구)

  • 이현우;이석건
    • Journal of Bio-Environment Control
    • /
    • v.2 no.1
    • /
    • pp.46-52
    • /
    • 1993
  • The wind pressure distributions were analyzed through the wind tunnel experiment to provide fundamental criteria for the structural design on the three-span arched house according to the wind directions. In order to investigate the wind force distribution, the variation of the wind force coefficients, the mean wind force coefficients, the drag force coefficients and the lift force coefficients were estimated from the experimental data. The results obtained are as follows : 1. The variation of the wind force with the wind directions on the side walls was the greatest at the upwind edge of the walls. The change of pressure from the positive to the negative on the side walls occurred at the wind direction of 30$^{\circ}$ in the first house and 60$^{\circ}$ in the third house. 2. The maximum negative wind force along the length of the roof appeared at the length ratio of 0-0.2, when the wind directions were 90$^{\circ}$ in the first house, 60$^{\circ}$ in the second house and 30$^{\circ}$ in the third house. 3. The maximum negative wind force along the width of the roof appeared at the width ratio and the wind direction of 0.4 and 0$^{\circ}$ in the first house, 0.4-0.6 and 30$^{\circ}$ in the second house and 0.6 and 30$^{\circ}$ in the third house, respectively. 4. The maximum mean positive and negative wind forces occurred at the wind direction of 60$^{\circ}$ and 30$^{\circ}$, respectively, on the side walls of the first house, and the maximum mean negative wind force on the roof occurred at the wind direction of 30$^{\circ}$ in third house. 5. The maximum drag and lift forces occurred at the wind direction of 30$^{\circ}$, and the maximum lift force appeared in the third house. 6. The parts to be considered for the local wind forces were the edges of the walls, the edges of the x-direction of the roofs, and the locations of the width ratio of 0.4 of the first and third house and the center of the width of the second house for the y-direction of the roofs.

  • PDF

Battery energy storage system for 10kW wind turbine output stabilization (배터리 에너지 저장장치를 이용한 10kW 풍력발전출력 안정화 시스템 개발)

  • Oh, Seung-Jin;Han, Byung-Moon
    • Proceedings of the KIPE Conference
    • /
    • 2010.11a
    • /
    • pp.36-37
    • /
    • 2010
  • This paper presents a simulation model and results of experiment about analysis of grid-tied wind turbine generator with batteries. The system consists of two inverters and a bidirectional DC/DC converter. These inverters are to capture the maximum active power under varying wind conditions and to keep the DC-link voltage magnitude at a specific level. And the bidirectional DC/DC converter makes battery charging or discharging depend on power gap between wind turbine output and local load.

  • PDF

Study on Present Status and Future Direction of Korean Offshore Wind Power (한국의 해상풍력 현황과 발전방향에 관한 연구)

  • Sung, Jin Ki;Lee, Tae Jin
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.62 no.3
    • /
    • pp.312-321
    • /
    • 2013
  • In this study, we review the status of Southwest sea 2.5GW offshore wind project and expected various problems. And we suggest government policies for offshore wind industrialization. Especially, we would like to mention the necessity of offshore wind development in order to diversify power sources and guarantee energy security in Korea. And we would like to mention necessity and direction to make offshore wind into growth engine industry thorough fusion between industries and energization for the existing industry such as civil, shipbuilding, steel, etc. that was headed into downturn.

A summertime near-ground velocity profile of the Bora wind

  • Lepri, Petra;Kozmar, Hrvoje;Vecenaj, Zeljko;Grisogono, Branko
    • Wind and Structures
    • /
    • v.19 no.5
    • /
    • pp.505-522
    • /
    • 2014
  • While effects of the atmospheric boundary layer flow on engineering infrastructure are more or less known, some local transient winds create difficulties for structures, traffic and human activities. Hence, further research is required to fully elucidate flow characteristics of some of those very unique local winds. In this study, important characteristics of observed vertical velocity profiles along the main wind direction for the gusty Bora wind blowing along the eastern Adriatic coast are presented. Commonly used empirical power-law and the logarithmic-law profiles are compared against unique 3-level high-frequency Bora measurements. The experimental data agree well with the power-law and logarithmic-law approximations. An interesting feature observed is a decrease in the power-law exponent and aerodynamic surface roughness length, and an increase in friction velocity with increasing Bora wind velocity. This indicates an urban-like velocity profile for smaller wind velocities and rural-like velocity profile for larger wind velocities, which is due to a stronger increase in absolute velocity at each of the heights observed as compared to the respective velocity gradient (difference in average velocity among two different heights). The trends observed are similar during both the day and night. The thermal stratification is near neutral due to a strong mechanical mixing. The differences in aerodynamic surface roughness length are negligible for different time averaging periods when using the median. For the friction velocity, the arithmetic mean proved to be independent of the time record length, while for the power-law exponent both the arithmetic mean and the median are not influenced by the time averaging period. Another issue is a large difference in aerodynamic surface roughness length when calculating using the arithmetic mean and the median. This indicates that the more robust median is a more suitable parameter to determine the aerodynamic surface roughness length than the arithmetic mean value. Variations in velocity profiles at the same site during different wind periods are interesting because, in the engineering community, it has been commonly accepted that the aerodynamic characteristics at a particular site remain the same during various wind regimes.