具有大实度直线翼垂直轴风力机气动特性数值模拟

针对实度对直线翼垂直轴风力机气动特性的影响,以采用NACA0018翼型小型直线翼的垂直轴风力机为对象,选取了0.30和0.35共2种较大的实度,每种实度下的叶片数分别为3,4,5.利用数值模拟的方法研究不同条件下直线翼垂直轴风力机的静态启动特性和动态功率特性.结果表明:在大实度情况下,叶片数对风力机气动特性的影响较大.在相同实度时,叶片数的增加能够降低各个方位角下静态力矩系数的波动,并对反向力矩有所改善,但会使最大力矩系数降低;在旋转状态下,叶片数的增加会减小最佳尖速比前的功率系数上升速度并降低功率系数,且最佳尖速比后的功率系数降低速度也减小.当叶片数相同时,具有0.35实度的风力机静态平均力矩系数大,且多数方位角下的力矩系数大于实度为0.30的风力机;在风力机旋转状态下,实度为0.30的风力机最大功率系数大于实度为0.35的风力机.

Numerical simulation of aerodynamic characteristics of straight-bladed vertical axis wind turbine with large solidities

Solidity is one of the important structural parameters that affect the aerodynamic characteristics of vertical axis wind turbines. The NACA0018 airfoil small straight-bladed vertical axis wind turbine was used as the object. Two large solidities of 0.30 and 0.35 were selected. The number of blades in each solidity was 3, 4, and 5 respectively. The method of numerical simulation was used to study the static starting characteristics and dynamic power characteristics of the straight-bladed vertical axis wind turbine. The results show that: in the case of large solidity, the number of blades has a greater influence on the aerodynamic characteristics of the wind turbine. At the same degree solidity, the increase of the blades number can improve the fluctuation of the static torque coefficient at various azimuth angles, and reduce the reverse torque, but decrease the maximum torque coefficient; In the rotating state, the increase in the number of blades will decrease the power coefficient rising speed before the optimal tip speed ratio, reduce the power coefficient, and decrease the power coefficient reduce speed after the optimal tip speed ratio. When the number of blades is the same, the static ave-rage torque coefficient of a wind turbine with 0.35 of solidity is large, and the torgre coefficients at most of the azimuth are greater than those with 0.30 of solidity; However, with respect to the rotating state, the maximum power coefficient of a wind turbine with a 0.30 solidity is greater than that of wind turbine with a 0.35 wind turbine.