基于UDF的水平轴潮流能水轮机被动旋转水动力性能研究

Study on hydrodynamic performance of horizontal tidal turbine rotating passively based on UDF

针对水平轴潮流能水轮机被动旋转问题,基于Fluent 17.0,运用UDF(User Defined Function)控制滑移网格对网格进行动态调整,仿真研究水轮机在不同安放角下被动旋转的水动力特性。通过仿真分析,结果表明:潮流能水轮机随着叶片安放角度的增加,尖速比、输出功率、捕能系数都是先增大后减小,叶片安放角为6°时,叶轮前后速度差最大,对潮流能利用充分,且各项性能均达到最佳;通过分析叶片受力,叶尖叶素在安放角为2°时阻力最大,3°时升力最大,升阻比在6°时最大,此时叶尖叶素升阻比C_L/C_D=6.27、攻角α=3.06°。由仿真结果可知水平轴潮流能叶轮的自启动过程由5个阶段组成,即加速度增大的加速运动段—加速度减小的加速运动段—加速度反向增大的减速运动段—加速度反向减小的减速运动段—稳定运行段,这对潮流能水轮机的设计具有重要的指导意义。

Aiming at the problem of horizontal tidal turbine rotating passively,and using UDF(User Defined Function)to control the sliding mesh to adjust grid dynamically by Fluent 17.0,the hydrodynamic performance of passive rotating for various pitch angles w,as studied.Results show that with pitch angel increasing,all of its tip speed ration,output power and energy-catching coefficient increase first and then decrease,the velocity difference is much larger in front and at back of the rotor for 6°pitch angle,the use of velocity energy is sufficient,and they are all optimum for 6°pitch angle.Analyzing the force of Blade-tip airfoil shows that its maximum drag is at 2°pitch angle,maximum lift is at 3°pitch angle,optimal lift-drag ratio is 6.27 at 6°pitch angle and its attach angle is 3.06.The starting-up process of turbine has five phases:accelerating motion of angular acceleration increasing,accelerating motion of angular acceleration decreasing,accelerating motion of negative angular acceleration increasing,accelerating motion of negative angular acceleration decreasing and stability,which is of guiding significance to the design of tidal turbine.