• Title/Summary/Keyword: Numerical wind tunnel

Search Result 352, Processing Time 0.023 seconds

Wind-excited stochastic vibration of long-span bridge considering wind field parameters during typhoon landfall

  • Ge, Yaojun;Zhao, Lin
    • Wind and Structures
    • /
    • v.19 no.4
    • /
    • pp.421-441
    • /
    • 2014
  • With the assistance of typhoon field data at aerial elevation level observed by meteorological satellites and wind velocity and direction records nearby the ground gathered in Guangzhou Weather Station between 1985 and 2001, some key wind field parameters under typhoon climate in Guangzhou region were calibrated based on Monte-Carlo stochastic algorithm and Meng's typhoon numerical model. By using Peak Over Threshold method (POT) and Generalized Pareto Distribution (GPD), Wind field characteristics during typhoons for various return periods in several typical engineering fields were predicted, showing that some distribution rules in relation to gradient height of atmosphere boundary layer, power-law component of wind profile, gust factor and extreme wind velocity at 1-3s time interval are obviously different from corresponding items in Chinese wind load Codes. In order to evaluate the influence of typhoon field parameters on long-span flexible bridges, 1:100 reduced-scale wind field of type B terrain was reillustrated under typhoon and normal conditions utilizing passive turbulence generators in TJ-3 wind tunnel, and wind-induced performance tests of aero-elastic model of long-span Guangzhou Xinguang arch bridge were carried out as well. Furthermore, aerodynamic admittance function about lattice cross section in mid-span arch lib under the condition of higher turbulence intensity of typhoon field was identified via using high-frequency force-measured balance. Based on identified aerodynamic admittance expressions, Wind-induced stochastic vibration of Xinguang arch bridge under typhoon and normal climates was calculated and compared, considering structural geometrical non-linearity, stochastic wind attack angle effects, etc. Thus, the aerodynamic response characteristics under typhoon and normal conditions can be illustrated and checked, which are of satisfactory response results for different oncoming wind velocities with resemblance to those wind tunnel testing data under the two types of climate modes.

Analysis of Aerodynamic Noise at Inter-coach Space of High Speed Trains

  • Kim, Tae-Min;Kim, Jung-Soo
    • International Journal of Railway
    • /
    • v.7 no.4
    • /
    • pp.100-108
    • /
    • 2014
  • A numerical analysis method for predicting aerodynamic noise at inter-coach space of high-speed trains, validated by wind-tunnel experiments for limited speed range, is proposed. The wind-tunnel testing measurements of the train aerodynamic sound pressure level for the new generation Korean high-speed train have suggested that the inter-coach space aerodynamic noise varies approximately to the 7.7th power of the train speed. The observed high sensitivity serves as a motivation for the present investigation on elucidating the characteristics of noise emission at inter-coach space. As train speed increases, the effect of turbulent flows and vortex shedding is amplified, with concomitant increase in the aerodynamic noise. The turbulent flow field analysis demonstrates that vortex formation indeed causes generation of aerodynamic sound. For validation, numerical simulation and wind tunnel measurements are performed under identical conditions. The results show close correlation between the numerically derived and measured values, and with some adjustment, the results are found to be in good agreement. Thus validated, the numerical analysis procedure is applied to predict the aerodynamic noise level at inter-coach space. As the train gains speed, numerical simulation predicts increase in the overall aerodynamic sound emission level accompanied by an upward shift in the main frequency components of the sound. A contour mapping of the aerodynamic sound for the region enclosing the inter-coach space is presented.

Wind Flow over Hilly Terrain (언덕지형을 지나는 유동에 관한 연구)

  • 임희창;김현구;이정묵;경남호
    • Journal of Korean Society for Atmospheric Environment
    • /
    • v.12 no.4
    • /
    • pp.459-472
    • /
    • 1996
  • An experimental investigation on the wind flow over smooth bell-shaped two-dimensional hills with hill slopes (the ratio of height to half width) of 0.3 and 0.5 is performed in an atmospheric boundary-layer wind tunnel. Two categories of the models are used in the present investigation; six two-dimensional single-hills, and four continuous double-hills. The measurements of the flow field and surface static-pressure distribution are carried out over the Reynolds number (based on the hill height) of 1.9 $\times 10^4, 3.3 \times 10^4, and 5.6 \times 10^4$. The velocity profiles and turbulence characteristics are measured by the pitot-tube and X-type hot-wire anemometer, respectively. The undisturbed boundary-layer profile on the bottom surface of the wind tunnel is reasonably consistent with the power-law profile with $\alpha = 7.0 (1/\alpha$ is the power-law exponent) and shows good spanwise uniformities. The profiles of turbulent intensity are found to be consistent along the centerline of the wind tunnel. The measured non-dimensional speed-up profiles at the hill crest show good agreements with the predictions of Jackson and Hunt's linear theory. The flow separation occurs in the hill slope of 0.5, and the oil-ink dot method is used to find the reattachment points in the leeside of the hill. The measured reattachment points are compared with the numerical predictions. Comparisons of the mean velocity profiles and surface pressure distributions between the numerical predictions and the experimental results show good agreements.

  • PDF

Estimation of the Wind Forces of Ieodo Ocean Research Station by a Wind Tunnel Test (풍동실험에 의한 이어도 해양과학기지의 풍력산정)

  • 심재설;전인식;황종국;오병철
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.14 no.2
    • /
    • pp.161-170
    • /
    • 2002
  • A wind tunnel experiment was performed with the design wind speed of 50m/s to investigate the wind forces of Ieodo Ocean Research Station. The structure portion above water surface was modelled with 1/80 scale ratio. The wind force coefficients were determined from the force signals and compared to the results of a numerical study which was separately undertaken. Those results generally agreed well, and it is assured that the experimental data can be effectively used in the wind resistant design of the structure. Making use of the experimental force and pressure coefficients, the wind farce and moments acting on the overall upper structure of prototype are determined together with the wind pressures on local impervious facilities (main deck, solar panel and helideck).

Study for the Power Characteristic of NREL Phase VI Blade considering Wind Shear (Wind Shear를 고려한 NREL Phase VI 블레이드의 출력특성연구)

  • Park, Sangjun;Lee, Kyungseh;Kim, Youngchan;Park, Hyunchul
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 2011.05a
    • /
    • pp.56.2-56.2
    • /
    • 2011
  • As rotor blade of a wind turbine becomes larger to satisfy the economic efficiency for offshore wind farm, the numerical analysis considering wind profile is getting emphasized. In this paper, the study for the power characteristic of a wind turbine is carried out using NREL phase VI wind turbine applied wind profile. The experimental data of NASA Ames wind tunnel for inflow velocity 7m/s is used and the numerical result is obtained by using CFD commercial solver(FLUENT).

  • PDF

Generation of a Turbulent Boundary Layer Using LES (LES를 이용한 난류경계층의 생성에 관한 연구)

  • Lim, Hee-Chang
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.31 no.8
    • /
    • pp.680-687
    • /
    • 2007
  • The paper presents a numerical simulation of flow of a turbulent boundary layer, representing a typical wind environment and matching a series of wind tunnel observations. The simulations are carried out at a Reynolds number of 20,000, based on the velocity U at a pseudo-height h, and large enough that the flow be effectively Reynolds number independent. Some wall models are proposed for the LES(Large Eddy Simulation) of the turbulent boundary layer over a rough surface. The Jenson number, $J=h/z_0$, based on the roughness length $z_0$, is 600 to match the wind tunnel data. The computational mesh is uniform with a spacing of h/32, as this aids rapid convergence of the multigrid solver, and the governing equations are discretised using second order finite differences within a parallel multiblock environment. The results presented include the comparison between wind tunnel measurements and LES computations of the turbulent boundary layer over rough surface.

Application of the E-$\varepsilon$turbulence numerical model to a flow and dispersion around triangular ridge( I ) (E-$\varepsilon$모델을 이용한 삼각 봉우리 주변의 유동과 확산 수치해석(I))

  • 정상진
    • Journal of Korean Society for Atmospheric Environment
    • /
    • v.10 no.2
    • /
    • pp.116-123
    • /
    • 1994
  • The E- $\varepsilon$ turbulence numerical model was applied to a flow around triangular ridge in neutral boundary layer. Scale of cavity region, mean velocity, Reynolds stress and eddy diffusivity were investigated. The height of cavity region was in satifactory agreement with the wind tunnel data while the length of cavity region was underestimated. The man wind velocities outside the cavity region were well Predicted by the model, however in cavity region the mean wind velocities of wind tunnel data were larger than the model results Reynolds stress of cavity region was overestimated by the model. The eddy diffusivity of wake region was strongly modified under the influence of triangular ridge. The local minimum of the eddy diffusivity was occured in the lee of the ridge top.

  • PDF

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.

VALIDATION OF TRANSITION FLOW PREDICTION AND WIND TUNNEL RESULTS FOR KU109C ROTOR AIRFOIL (로터 익형 KU109C 풍동시험 및 천이유동 해석결과의 검증)

  • Jeon, S.E.;Sa, J.H.;Park, S.H.;Kim, C.J.;Kang, H.J.;Kim, S.B.;Kim, S.H.
    • Journal of computational fluids engineering
    • /
    • v.17 no.1
    • /
    • pp.54-60
    • /
    • 2012
  • Transition prediction results are validated with experimental data obtained from a transonic wind tunnel for the KU109C airfoil. A Reynolds-Averaged Navier-Stokes code is simultaneously coupled with the transition transport model of Langtry and Menter and applied to the numerical prediction of aerodynamic performance of the KU109C airfoil. Drag coefficients from the experiment are better correlated to the numerical prediction results using a transition transport model rather than the fully turbulent simulation results. Maximum lift coefficient and drag divergence at the zero-lift condition with Mach number are investigated. Through the present validation procedure, the accuracy and usefulness of both the experiment and the numerical prediction are assessed.