霜冰条件下风力机翼型结冰的数值计算预测

Numerical Simulation Prediction of Icing on Airfoil of Wind Turbine Blade Under Rime Ice Conditions

借助ANSYS FLUENT平台,通过嵌入水滴撞击模块、结冰增长模块开展了风力机翼型NACA63418在霜冰条件下的结冰模拟预测。利用欧拉法基于UDS框架求解水滴撞击特性,角平分线法模拟冰型增长,计算了NACA0012翼型的水撞击及结冰冰形,与实验对比后验证了所发展的霜冰计算方法的准确性,对比分析了不同参数条件下NACA63418翼型表面的水滴收集系数分布及结冰冰形。计算翼型模型弦长为1 m,攻角变化范围为0°~12°,环境温度为253.15 K,空气中的液态水含量范围为0.6~1.3 g/m3,水滴平均粒径范围为20~30μm,自由来流风速范围为30~50 m/s。研究表明,翼型表面的最大水滴收集系数和水滴撞击范围与来流风速和水滴直径成正相关,水滴撞击范围随着攻角增大而增大,压力面撞击极限变化幅度大于吸力面撞击极限幅度,收集系数分布趋势变化不大;低温情况下表面形成规则的楔形冰,结冰量随着水滴直径、自然来流速度和液态水含量的增大而增加,随着攻角增大,结冰区域向压力面移动,结冰极限点向下移动的幅度随着攻角增大而减小,结冰面积增大,但结冰最大厚度变化不明显,0°攻角下25 min后的结冰冰形最大厚度为5.9 cm。

With the help of ANSYS FLUENT platform,the ice simulation and prediction of NACA63418 under the rime ice condition are carried out by embedding the water drop impact module and ice growth module.The water droplet collection efficiency was simulated by using the Euler method based on the UDS framework,the angle bisector method was used to simulate the ice shape growth.The water droplet collection efficiency and ice shape of the NACA0012 airfoil were simulated and the accuracy of the method of rime ice was proved by comparing the experimental data.The water droplet collection efficiency and icing ice type of the NACA63418 airfoil under different conditions were compared and analyzed.The airfoil chord length is 1 m,the angle of attack varies from 0°to 12°,the ambient temperature is 253.15 K,the liquid water content in the air ranges from 0.6 to 1.3 g/m3,and the average water droplet size ranges from 20 to 30μm.The wind speed ranges from 30 to 50 m/s.The research shows that the maximum water droplet collection efficiency and water droplet impact range on the airfoil surface is positively correlated with the wind speed and water droplet diameter.The impact range of the water droplet increases with the angle of attack,and the pressure surface impact limit range is larger than the suction surface impact limit.The distribution trend of the water droplet collection efficiency does not change much;the ice type formed under low temperature is relatively regular,and the ice amount increase with the increase of water droplet diameter,natural flow velocity and liquid water content.As the angle of attack increases,the icing area moves toward the pressure surface and the extent of the downward movement of the icing limit point decreases.The icing area increases but the maximum thickness of icing changes is not obvious.The maximum thickness of the frozen ice type after 25 minutes is about 5.9 cm when the angle of attack is 0°.