A novel real-time feedback pitch angle control system for vertical-axis wind turbines

2019 ◽  
Vol 195 ◽  
pp. 104023
Author(s):  
Linjun Chen ◽  
Yuzhuo Yang ◽  
Ye Gao ◽  
Zheming Gao ◽  
Yonghui Guo ◽  
...  
Author(s):  
Kenneth A. Williams ◽  
Christina N. Yarborough ◽  
James E. Smith

In the latter half of the twentieth century extensive research had been performed to improve the efficiency and operational life of Vertical axis wind turbines (VAWTs) in order to make them competitive with the more common horizontal axis wind turbines (HAWTs). Due to the completely random wind conditions and a continuously changing angle of attack of the rotating airfoil, fatigue of the system components was a major contributor to the short operational life of these traditional VAWTs. The fluctuating aerodynamic forces generated by the airfoil during rotation subject the support shaft to a substantial amount of torque ripple. In addition to the varying torque produced by the turbine, the centripetal forces generated by the airfoil’s rotation proved to be extremely large and create problems with deflection and fatigue in the airfoil’s internal support structure and especially at the attachment point of the airfoil to the support arm. One method for improving the efficiency of an aerodynamic system is to reduce the weight of the system. However, because of the forces generated during turbine operation, this proved to be a nontrivial task. West Virginia University’s (WVU) Center for Industrial Research Applications (CIRA) is exploring the implementation of circulation control on a vertical axis wind turbine to increase the lift to drag ratio of the turbine’s airfoils in order to produce a greater turning force and improve the efficiency of the system. While the common structural challenges of vertical axis wind turbines still apply, those implementing circulation control introduce additional design hurdles which must be overcome. These additional design problems concern mainly with the airfoil construction and support shaft in that they must be capable of accommodating the circulation control system components. This paper introduces the geometrical design constraints imposed on a vertical axis wind turbine through the operational requirements and serviceability of the circulation control system in addition to the traditional aerodynamic and centripetal forces generated and how they are resolved onto the individual turbine components.


Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2286
Author(s):  
Yutaka Hara ◽  
Yoshifumi Jodai ◽  
Tomoyuki Okinaga ◽  
Masaru Furukawa

To investigate the optimum layouts of small vertical-axis wind turbines, a two-dimensional analysis of dynamic fluid body interaction is performed via computational fluid dynamics for a rotor pair in various configurations. The rotational speed of each turbine rotor (diameter: D = 50 mm) varies based on the equation of motion. First, the dependence of rotor performance on the gap distance (gap) between two rotors is investigated. For parallel layouts, counter-down (CD) layouts with blades moving downwind in the gap region yield a higher mean power than counter-up (CU) layouts with blades moving upwind in the gap region. CD layouts with gap/D = 0.5–1.0 yield a maximum average power that is 23% higher than that of an isolated single rotor. Assuming isotropic bidirectional wind speed, co-rotating (CO) layouts with the same rotational direction are superior to the combination of CD and CU layouts regardless of the gap distance. For tandem layouts, the inverse-rotation (IR) configuration shows an earlier wake recovery than the CO configuration. For 16-wind-direction layouts, both the IR and CO configurations indicate similar power distribution at gap/D = 2.0. For the first time, this study demonstrates the phase synchronization of two rotors via numerical simulation.


Author(s):  
Xiaomin Chen ◽  
Ramesh Agarwal

In this paper, we consider the Wind Farm layout optimization problem using a genetic algorithm. Both the Horizontal–Axis Wind Turbines (HAWT) and Vertical-Axis Wind Turbines (VAWT) are considered. The goal of the optimization problem is to optimally place the turbines within the wind farm such that the wake effects are minimized and the power production is maximized. The reasonably accurate modeling of the turbine wake is critical in determination of the optimal layout of the turbines and the power generated. For HAWT, two wake models are considered; both are found to give similar answers. For VAWT, a very simple wake model is employed.


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