Flow Characteristics of a Straight-Bladed Vertical Axis Wind Turbine with Inclined Pitch Axes

Abstract

Currently, vertical axis wind turbines (VAWT) are considered as an alternative technology to horizontal axis wind turbines in specific wind conditions, such as offshore farms. However, complex unsteady wake structures of VAWTs exert a significant influence on performance of wind turbines and wind farms. In the present study, instantaneous flow fields around and downstream of an innovative VAWT with inclined pitch axes are simulated by an actuator line model. Unsteady flow characteristics around the wind turbine with variations of azimuthal angles are discussed. Several fluid parameters are then evaluated on horizontal and vertical planes under conditions of various fold angles and incline angles. Results show that the total estimated wind energy in the shadow of the wind turbine with an incline angle of 30° and 150° is 4.6% higher than that with an incline angle of 90°. In this way, appropriate arrangements of wind turbines with various incline angles have the potential to obtain more power output in a wind farm.

On the wake deflection of vertical axis wind turbines by pitched blades

“…Jadeja (2018) 28 investigated the wake deflection of a pitched VAWT using the actuator line model together with unsteady Reynolds averaged Navier–Stokes (RANS) simulation. Based on the same numerical method, Guo and Lei (2020) 29 presents the deflected wake of a VAWT with inclined pitching axis.…”

“…The main reasons are (a) faster wake recovery, allowing for a closer interturbine distance 25 ; (b) less susceptible to flow turbulence, allowing for a more flexible layout to be deployed 26 ; (c) in addition to the conventional aligned or staggered layout, synergistic clusters can increase farm efficiency 27 ; and (d) simpler wake deflection mechanics. As opposed to yawed or tilted HAWTs that require the nacelle or tower to move, VAWTs can redirect the wake via pitched blades 28,29 or struts connecting the blades. 30 The wake of VAWTs, on the other hand, is significantly more complex, and the physics underlying its deflection is still not fully understood.…”

“…Top view of a simplified three-dimensional actuator cylinder, the AC is divided into four regions follows the convention of a clockwise rotating VAWT, with capital letters denoting corresponding quadrants (e.g., UW: upwind-windward) model together with unsteady Reynolds averaged Navier-Stokes (RANS) simulation. Based on the same numerical method, Guo and Lei (2020) 29 presents the deflected wake of a VAWT with inclined pitching axis.…”

Performance Analysis of a Full Order Sensorless Control Adaptive Observer for Doubly-Fed Induction Generator in Grid Connected Operation

“…In the grid-connected system, the aim is to maximize the conversion of mechanical input energy from the wind turbine into electric energy, ensuring the minimization of the cost of energy at the same time [4,5]. To meet this goal, the more widespread wind power generation system, for both small and large power, consists of a wind turbine [6,7], usually equipped with pitch control limits, a gearbox, and a DFIG directly connected to the AC grid on the stator side and driven through a power electronic converter on the rotor side. The rating of the power electronic is almost 25% of the rated power, allowing a speed range from nearly 50% to 120% of the rated speed [8].…”

Numerical Analysis and Parameter Optimization of J-Shaped Blade on Offshore Vertical Axis Wind Turbine

“…Due to the high utilization rate of wind energy and mature technology of large-scale horizontal axis offshore wind turbines, large-scale wind power generation is now mostly horizontal axis, which occupies a large share in both offshore wind power and onshore wind power [7,8]. While the larger size of the offshore wind turbine helps reduce the cost of generating electricity, it also significantly increases the cost of operation and maintenance, especially for offshore wind turbines that require installation and maintenance on specific vessels [9,10]. With the increase of the size of offshore wind turbines, the cost of power generation is reduced, which also brings difficulties to the construction and maintenance of large-scale offshore wind turbines [11].…”