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This study examined the aerodynamic power output change of wind turbines with inter-turbine spacing variation for a 6 MW wind farm composed of three sets of 2 MW wind turbines using computational fluid dynamics (CFD). The wind farm layout design is becoming increasingly important as the use of wind energy is steadily increasing. Among the many wind...
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Context 1
... analysis can be used to analyze large-scale problems, and the application of CFD to the layout design of offshore wind farms is expected to proliferate rapidly as the offshore wind farm market grows. Figure 1 shows various layout designs of wind farms depending on the site conditions, access convenience and maintenance conditions. The layout design of wind farms will become increasingly important as offshore wind farm with larger capacity are developed [8,9]. ...
Context 2
... there are many possible layouts for a wind farm as shown in Figure 1, the in-line configuration turns out to be a canonical layout for an offshore wind farm. The power deficit of the downstream wind turbines is mainly caused by wake flows from the upstream wind turbines, therefore, only one flow direction which is parallel to the wind turbines is considered. ...
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Citations
... Many researches are conducted to focus on the complicated wake characteristics in the wind farm. Choi et al. [8,9] investigated the wake interactions between three 2-MW wind turbines with tandem layout. The dynamic responses of the wind turbine including the aerodynamic loads and the wake velocity field were analyzed. ...
... The fracture aperture was first used as the control condition to construct an indoor physical model, and head loss and velocity were observed to analyze the characteristics of the fluid in the single fissure. Following the verification of the computational fluid dynamics (CFD) model in simulation of characteristics of the fluid in the single fissure with parameters most used [24][25][26][27][28], the relationship between the shape of the fracture (corner θ) and head loss was studied using it. ...
Local head loss caused by fracture intersection is often ignored because there has not been a simple method to calculate it until now. Relevant research shows that neglecting the local flow resistance leads to inaccurate results, especially when the velocity and cross angle are large. Therefore, it is necessary to find a portable method for calculation. Physical experiments of single fracture with different apertures (e = 0.77, 1.18, 1.97, 2.73 mm) were set up first to study the flow characteristics, showing obvious non-Darcian flow, which can be depicted by the Forchheimer equation when the flow velocity is sufficiently large. The computational fluid dynamics (CFD) software ANSYS FLUENT was used to build numeric simulation models. A good correlation between CFD simulation results and physical experiment results was found (Pearson’s correlation coefficient > 0.99). Then, the CFD models of flexural crack with different angles from 30° to 150° were established to compute the pressure drop of flexural crack at different velocity. It was found that the local head loss of the flexural crack varied with the bending angle, and its coefficient was expressed by the deformation of the logistic equation. By using this model, as well as a frictional head loss equation fitted by Forchheimer equation, the head loss of crossed fissures with fixed fracture aperture could be easily calculated.
... In the case of horizontal-axis wind turbines, the angle of attack due to the rotation of the wind turbine is constant. Many studies have been conducted on the prediction of the blades' aerodynamic characteristics, and many proprietary technologies have been established [10][11][12][13]. However, in the case of vertical-axis wind turbines, the angle of attack due to the rotation of the wind turbine changes continuously. ...
... The lift and drag coefficients (CL, CD) of the NACA 0018 in Table 3 are defined in Equations (12) and (13), respectively [30]. = 1 2 (12) = 1 2 (13) In these equations, the lift (FL) and drag (FD) are obtained through 2D CFD analysis, which was performed to investigate the aerodynamic performance of blades of the VAWT. Figure 4 shows the two-dimensional flow analysis domain and the position of the blade. ...
... The lift and drag coefficients (CL, CD) of the NACA 0018 in Table 3 are defined in Equations (12) and (13), respectively [30]. = 1 2 (12) = 1 2 (13) In these equations, the lift (FL) and drag (FD) are obtained through 2D CFD analysis, which was performed to investigate the aerodynamic performance of blades of the VAWT. Figure 4 shows the two-dimensional flow analysis domain and the position of the blade. The flow field was expanded to about 15D by the width of 7D based on the rotor diameter (D), 3D from the inlet of the flow field to the center of the rotor, and around the center of the rotor to the outlet. ...
A 100-W helical-blade vertical-axis wind turbine was designed, manufactured, and tested in a wind tunnel. A relatively low tip-speed ratio of 1.1 was targeted for usage in an urban environment at a rated wind speed of 9 m/s and a rotational speed of 170 rpm. The basic dimensions were determined through a momentum-based design method according to the IEC 61400-2 protocol. The power output was estimated by a mathematical model that takes into account the aerodynamic performance of the NACA0018 blade shape. The lift and drag of the blade with respect to the angle of attack during rotation were calculated using 2D computational fluid dynamics (CFD) simulation to take into account stall region. The average power output calculated by the model was 108.34 W, which satisfies the target output of 100 W. The manufactured wind turbine was tested in a large closed-circuit wind tunnel, and the power outputs were measured for given wind speeds. At the design condition, the measured power output was 114.7 W, which is 5.9% higher than that of the mathematical model. This result validates the proposed design method and power estimation by the mathematical model.
... The gross annual energy production (AEP) was then computed for a wind power plant composed of 10 WTGs, located at the most suitable locations according to the potential wind resource displayed in the microscale wind map. Wake effects [20] and inter-turbine spacing [21], known to lead to substantial power losses in wind power plants, were also taken into consideration in the AEP estimations. Thus, the net AEP is analyzed, with the theoretical, equivalent capacity factor (CF) computed using Eq. ...
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... Wind supplies competitive renewable energy for mankind's economic development, especially in the face of the issues of global warming and the shortage of energy supplies. The recent technology trend in the wind energy industry has been towards offshore wind power projects [1]. Offshore wind farms have distinct advantages over onshore wind farms, as well as various new situations and challenges, among which the typhoon has been one of the unavoidable problems [2]. ...
... As a result of the thin twist blades with their highly complex shape of the FX93-2500 wind turbine, the difficulty and quantity of the structured mesh generation are greatly increased. The fluid computational domain contained, on average, 13,953,703 hexahedral mesh elements, which was several times larger than the previous wind farm CFD studies [1,18,19,22,30,31]. ...
Super typhoon activity is likely to make the electric power network fail, or blow the wind-measuring device off, which all lead to the yaw control system of wind turbine being inactive. Under this condition, blades can be blown by the violent side wind from unfavorable directions, and the aerodynamic loads on the wind turbine will be increased by a large amount, which can lead to low-cycle fatigue damage and other catastrophic collapses. So far, not enough consideration has been given to the above problems in wind turbine design. Using the transient computational fluid dynamics (CFD), this study investigates the wind load characteristics of offshore wind turbines under typhoon condition with 360-degree full wind directions. Two primary influence factors of the aerodynamic characteristics of wind turbines are clarified: variation of the wind direction and different parking positions of the wind rotor. Using 3D-numerical simulation results, this study provides detailed references for the ultimate strength and fatigue life in wind turbine design, and presents the best parking position of the wind turbine with a free yawing strategy.
Limited by layout space and manufacturing costs, wake interaction in offshore wind farms is inevitable and can have adverse effects on the performance of downstream wind turbines. To gain a better understanding of the wake interaction between Floating Offshore Wind Turbines (FOWTs), this paper conducts coupled aero-hydrodynamic simulations for two spar-type FOWTs under different layouts. The Unsteady Actuator Line Model (UALM) is used to analyze the unsteady aerodynamic loads of the wind turbine, while the hydrodynamic responses of the floating support platform are obtained using the Computational Fluid Dynamics (CFD) method. To predict the aero-hydrodynamic performance of the FOWT under combined wind and waves, an in-house CFD code developed at Shanghai Jiao Tong University (SJTU), called FOWT-UALM-SJTU solver, is utilized. First, grid convergence test and time step sensitivity study are performed to determine appropriate simulation parameters. Subsequently, numerical simulations of two FOWTs under tandem and offset layouts are conducted to investigate the influence of wake interaction on the performance of downstream FOWT. The dynamic responses of the FWOT, including aerodynamic loads, platform motions, and wake characteristics, are analyzed in detail. From the simulation results and discussions, several conclusions are drawn. Both platform motions and wake interaction contribute to an increased variation range of inflow wind speed experienced by the downstream FOWT, thereby exacerbating the instability of its aerodynamic loads. Under the tandem layout, the platform motions of the upstream FOWT and the downstream FOWT exhibit opposite effects on the aerodynamic loads of the downstream FOWT. Moreover, platform motions increase turbulence intensity in the wake region, accelerating wake velocity recovery and widening the wake width.
