• Wind and Structures
• /
• 제37권4호
• /
• pp.315-329
• /
• 2023

We investigated the wind characteristics in the near-surface layer during the landfall of Typhoon Mujigae (2015) based on observations from wind towers in the coastal areas of Guandong province. Typhoon Mujigae made landfall in this region from 01:00 UTC to 10:00 UTC on October 4, 2015. In the region influenced by the eyewall of the tropical cyclone, the horizontal wind speed was characterized by a double peak, the wind direction changed by >180°, the vertical wind speed increased by three to four times, and the angle of attack increased significantly to a maximum of 7°, exceeding the recommended values in current design criteria. The vertical wind profile may not conform to a power law distribution in the near-surface layer in the region impacted by the eyewall and spiral rainband. The gust factors were relatively dispersed when the horizontal wind speed was small and tended to a smaller value and became more stable with an increase in the horizontal wind speed. The variation in the gust factors was the combined result of the height, wind direction, and circulation systems of the tropical cyclone. The turbulence intensity and the downwind turbulence energy spectrum both increased notably in the eyewall and spiral rainband and no longer satisfied the assumption of isotropy in the inertial subrange and the -5/3 law. This result was more significant in the eyewall area than in the spiral rainband. These results provide a reference for forecasting tropical cyclones, wind-resistant design, and hazard prevention in coastal areas of China to reduce the damage caused by high winds induced by tropical cyclones.

• Wind and Structures
• /
• 제17권2호
• /
• pp.203-225
• /
• 2013

An analysis framework for vehicle-bridge dynamic interaction system under turbulent wind is proposed based on the relevant theory of wind engineering and dynamics. Considering the fluctuating properties of wind field, the stochastic wind velocity time history is simulated by the Auto-Regressive method in terms of power spectral density function of wind field. The bridge is represented by three-dimensional finite element model and the vehicle by a multi-rigid-body system connected by springs and dashpots. The detailed calculation formulas of unsteady aerodynamic forces on bridge and vehicle are derived. In addition, the form selection of wind barriers, which are applied as the windbreak measures of newly-built railways in northwest China, is studied based on the suggested evaluation index, and the suitable values about height and porosity rate of wind barriers are studied. By taking a multi-span simply-supported box-girder bridge as a case study, the dynamic response of the bridge and the running safety indices of the train traveling on the bridge with and without wind barriers are calculated. The limit values of train speed with respect to different wind velocities are proposed according to the allowance values in the design code.

• Structural Engineering and Mechanics
• /
• 제63권6호
• /
• pp.809-824
• /
• 2017

The accurate evaluation of wind characteristics and wind-induced structural responses during a typhoon is of significant importance for bridge design and safety assessment. This paper presents an expectation maximization (EM) algorithm-based angular-linear approach for probabilistic modeling of field-measured wind characteristics. The proposed method has been applied to model the wind speed and direction data during typhoons recorded by the structural health monitoring (SHM) system instrumented on the arch Jiubao Bridge located in Hangzhou, China. In the summer of 2015, three typhoons, i.e., Typhoon Chan-hom, Typhoon Soudelor and Typhoon Goni, made landfall in the east of China and then struck the Jiubao Bridge. By analyzing the wind monitoring data such as the wind speed and direction measured by three anemometers during typhoons, the wind characteristics during typhoons are derived, including the average wind speed and direction, turbulence intensity, gust factor, turbulence integral scale, and power spectral density (PSD). An EM algorithm-based angular-linear modeling approach is proposed for modeling the joint distribution of the wind speed and direction. For the marginal distribution of the wind speed, the finite mixture of two-parameter Weibull distribution is employed, and the finite mixture of von Mises distribution is used to represent the wind direction. The parameters of each distribution model are estimated by use of the EM algorithm, and the optimal model is determined by the values of $R^2$ statistic and the Akaike's information criterion (AIC). The results indicate that the stochastic properties of the wind field around the bridge site during typhoons are effectively characterized by the proposed EM algorithm-based angular-linear modeling approach. The formulated joint distribution of the wind speed and direction can serve as a solid foundation for the purpose of accurately evaluating the typhoon-induced fatigue damage of long-span bridges.

• International Journal of Aeronautical and Space Sciences
• /
• 제8권2호
• /
• pp.11-16
• /
• 2007

This paper describes the cycloidal wind turbine, which is a straight blade vertical axis wind turbine using the cycloidal blade system. Cycloidal blade system consists of several blades rotating about an axis in parallel direction. Each blade changes its pitch angle periodically. Cycloidal wind turbine is different from the previous turbines. The wind turbine operates with optimum rotating forces through active control of the blade to change pitch angle and phase angle according to the changes of wind direction and wind speed. Various numerical experiments were conducted to develop a small vertical axis wind turbine of 1 kW class. For this numerical analysis, the rotor system equips four blades consisting of a symmetric airfoil NACA0018 of 1.0m in span, 0.22m in chord and 1.0m in radius. A general purpose commercial CFD program, STAR-CD, was used for numerical analysis. PCL of MSC/PATRAN was used for efficient parametric auto mesh generation. Variables of wind speed, pitch angle, phase angle and rotating speed were set in the numerical experiments. The generated power was obtained according to the various combinations of these variables. Optimal pitch angle and phase angle of cycloidal blade system were obtained according to the change of the wind direction and the wind speed. Based on data obtained from the above analysis, control device was designed. The wind direction and the wind speed were sensed by a wind indicator and an anemometer. Each blades were actuated to optimal performance values by servo motors.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2011년도 제37회 추계학술대회논문집
• /
• pp.777-780
• /
• 2011

초음속 풍동은 고속으로 운용되는 비행체나 유도무기의 개발에 있어 시험체 주위에서 나타나는 공기역학적 현상을 연구하고 특성을 대표하는 물리량을 측정하기 위해 주로 사용되는 지상시험 장비이다. 본 연구에서는 연구팀에서 보유하고 있는 소형 초음속 풍동이 갖는 시험 모델 크기의 제약을 완화하고자 $250mm{\times}200mm$ 의 시험부를 갖는 초음속 풍동을 설계하고 제작된 풍동의 성능 평가를 수행하였다. 제작된 풍동의 시험 마하수는 2.5이며 시험부에서 균일한 유동을 얻을 수 있도록 경계층 보정을 수행하여 노즐의 형상을 결정하였다.

• 한국도로학회논문집
• /
• 제11권2호
• /
• pp.45-54
• /
• 2009

산악지역이나 해안지역을 통과하는 도로의 경우 강한 바람이 부는 지점이 있고, 이러한 지점에서 차량이 바람에 의해 전도하거나 옆으로 방향이 바뀔 수 있다. 현행 도로 설계 기준에서 강한 바람의 영향은 무시하고 있지만, 향후 고속도로 설계속도가 높아지게 되면 강한 바람의 영향은 더욱 커지게 된다. 본 연구에서는 초고속 주행 상태로 주행하는 차량에 강한 바람이 부는 경우 차량의 전도와 이탈의 관계식을 통해 그 가능성에 대해 분석했다. 이 분석에서 차량의 종류, 곡선반경, 운전자들의 강한 바람에 대응하는 소요 시간, 차량 주행속도 그리고 풍속을 달리하면서 수식적으로 전도와 이탈량을 산출했다. 그 분석 결과 차량의 전도 측면에서는 풍속 50m/s 이내에서 곡선반경이 600m 이상이면 전도 위험은 없는 것으로 나타났다. 차량의 이탈 측면에서는 풍속이 15.0m/s 이상일 경우 차량의 속도를 제한 할 필요가 있으며 풍속이 25.0m/s 이상일 경우 통행제한을 할 필요가 있는 것으로 나타났다. 본 연구 결과는 향후 도로 설계 기준을 조정하는 경우 참고할 만하며, 특히 강한 바람이 자주 부는 지역을 통과하는 고규격 고속도로를 건설하는 경우 매우 유용한 결과가 될 것이다.

• Journal of Advanced Marine Engineering and Technology
• /
• 제28권5호
• /
• pp.847-852
• /
• 2004

The wind turbine blade is the equipment converted wind into electric energy. The effect of the blade has influence of the output power and efficiency of wind turbine. The design of blade is considered of lift-to-drag ratio. structure. a condition of process of manufacture and stable maximum lift coefficient, etc. This study is used the simplified method for design of the aerodynamic blade and aerodynamic analysis used blade element method This Process is programed by delphi-language. The Program has any input values such as tip speed ratio blade length. hub length. a section of shape and max lift-to-drag ratio. The Program displays chord length and twist angle by input value and analyzes performance of the blade.

• 생물환경조절학회지
• /
• 제3권1호
• /
• pp.1-9
• /
• 1994

본 연구는 상대적으로 활하중의 영향이 민감하게 작용하는 농업시설의 합리적 구조설계를 위하여 우리나라 60개 지역의 자료를 사용하여 중요한 설계하중의 결정요인인 단위적설중량, 순간최대풍속 및 최대신적설심의 그 적용에 관하여 검토하였고, 얻어진 결과를 요약하면 다음과 같다. 1. 적설심에 다른 단위적설중량을 분석한 결과 적설심에 따른 차이는 발견할 수 없었고 대체적으로 정규분포를 이루고 있다. 평균기온에 의하여 단위중량을 구분해본 결과 -1$^{\circ}C$ 이상에서는 단위중량이 평균 0.91kg/cm/$m^2$, -1$^{\circ}C$ 이하에서는 평균 0.58kg/cm/$m^2$로 나타나 기온에 의한 차이가 명확했다. 2. 평균최대풍속과 순간최대풍속과의 관계를 도출하여 회귀식을 유도한 결과, 일반적으로 사용하고 있는 순간최대풍속 관계식과는 약간의 차이를 보였다. 해안지방과 내륙지방에 2개지역으로 구분하여 순간최대풍속 관계식을 유도하였다. 3. 재현기간별 최대적설심과 최대신적설심을 비교한 결과, 눈이 적은 지방에서는 큰 차이가 없으나, 비교적 눈이 많은 지방의 경우 재현기간 8년에서는 24.6cm, 57년에서는 45.6cm로 큰 차이를 보여, 난방 및 적절한 관리를 전제로 설계하면 신적설에 의하여 설계하중을 크게 감소시킬 수 있음을 나타냈다. 4. 기존식과 수정식의 설계풍속(진주지역) 및 최대적설심과 최대신적설심(서산지역)의 적용시, 2연동아치형시설의 부재사용량은 각각의 경우에 대하여 +0.3배, -0.3배이었고, 2연동지붕형 시설의 부재사용량은 각각 +0.3배, -0.1배이었기 때문에 시설의 특성에 맞는 설계자료의 선정이 매우 중요하다.

• Wind and Structures
• /
• 제17권1호
• /
• pp.43-68
• /
• 2013

The fluctuating wind induced vibration is one of the most important factors which has been taken into account in the design of long-span bridge due to the low stiffness and low natural frequency. Field measurement characteristics of sustained wind on structure site can provide accurate wind load parameters for wind field simulation and structural wind resistance design. As a suspension bridge with 1490 m main span, the Runyang Suspension Bridge (RSB) has high sensitivity to fluctuating wind. The simultaneous and continuously wind environment field measurement both in mid-span and on tower top is executed from 2005 up to now by the structural health monitoring system installed on this bridge. Based on the recorded data, the wind characteristic parameters, including mean wind speed, wind direction, the turbulence intensity, the gust factors, the turbulence integral length, power spectrum and spatial correlation, are analyzed in detail and the coherence functions of those parameters are evaluated using statistical method in this paper. The results indicate that, the turbulence component of sustain wind is larger than extremely strong winds although its mean wind speed is smaller; the correlation between turbulence parameters is obvious; the power spectrum is special and not accord with the Simiu spectrum and von Karman spectrum. Results obtained in this study can be used to evaluate the long term reliability of the Runyang Suspension Bridge and provide reference values for wind resistant design of other structures in this region.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
• /
• pp.631-638
• /
• 2003

The wind turbine blade is the equipment converted wind into electric energy. The effect of the blade has influence of the output power and efficiency of wind turbine. The design of blade is considered of lift-to-drag ratio, structure, a condition of process of manufacture and stable maximum lift coefficient, etc. This study is used the simplified method for design of the aerodynamic blade and aerodynamic analysis used blade element method. This process is programed by delphi-language. The program has any input values such as tip speed ratio, blade length, hub length, a section of shape and max lift-to-drag ratio. The program displays chord length and twist angle by input value and analyzes performance of the blade.