小型垂直轴风力机叶片结冰风洞试验与数值计算

摘要

The icing characteristics of rotating blade of a small-scaled Vertical Axis Wind Turbine (VAWT)and the aerodynamics performance changes of the iced blade airfoil and rotor were researched by wind tunnel tests and numerical simulation in order to provide technology reference for establishing the more complex test system for large scale Horizontal Axis Wind Turbine with rotating blade and study the icing mechanism and anti-icing and de-icing technology.The experiments were performed in an icing wind tunnel designed by Northeast Agricultural University using natural low temperature in cold winter.The test model was a small-scaled VAWT with 2 blades with NACA0018 airfoil.The icing accretions on rotating blade surface under 5 tip speed ratios were tested and recorded.Wind turbine blades were frozen over the entire surface of the blade.Ice shape asymmetry can be found on the blade with the increasing of tip speed ratio.Furthermore,the lift coefficient of iced blade decreased and drag coefficient increased with the increasing of tip speed ratio and the amount of ice based on the results of numerical simulation.The power coefficients of the rotor were also decreased.It can be also found that the change degree of pressure field and velocity field around the iced blade depended on rotating angles,which was the main reason affecting the aerodynamic performance of blade and the turbine.%利用风洞试验和数值模拟相结合的手段，研究了小型垂直轴风力机叶片在旋转状态下的结冰特性以及结冰后翼型与风力机的气动特性变化，以期为建立较复杂的大型水平轴风力机叶片旋转试验系统和研究其结冰机理、防除冰技术提供参考。试验在东北农业大学自行设计的利用自然低温的结冰风洞中进行，获得了采用NACA0018翼型的小型2叶片垂直轴风力机风轮在5种尖速比下的结冰分布：风力机叶片结冰遍布叶片整个表面，随着尖速比的增大，结冰形状出现不对称性。同时，数值模拟结果表明：叶片结冰后，随着尖速比的增加和结冰量的增多，升力系数降低阻力系数增大的趋势明显，风力机的功率系数也随之下降。分析发现，叶片结冰导致不同旋转角下叶片翼型周围的压力场和速度场发生了不同程度的变化，从而气动特性发生变化，影响了风力机性能。