主动转动水翼的空化水动力学特性研究

Cavity evolution in flows around active rotating hydrofoil

在构建新能源高占比的新型电力系统中,水电机组尤其是抽水蓄能机组,频繁在工况之间转换。活动导叶和轴流转桨叶片在主动调整过程中,其空化特性与稳定工况有较大区别,其空化发展机理值得深入研究。本文采用基于滤波器修正(FBM)的湍流模型和Zwart-Gerber-Belamri空化模型分别对两种不同水翼的转动方式下的空化水动力学特性进行数值模拟研究。对数值模拟结果中空化形态及流场速度矢量图进行分析,探究NACA0015水翼振荡运动中空泡演变和水动力参数的影响机理。结果表明,头部固定转动模式诱导的空泡尺度大于尾部固定模式,因为头部固定模式会加剧反向射流的运动。同时,当水翼头部固定时,时均汽相体积相对大于尾部固定振荡模式下的值。片空化工况下,对于两种不同的运动模式,汽相体积的总体曲线非常相似;云空化工况下,两种运动模式之间的汽相体积和空化形态曲线明显不同。

In the construction of a new power system with a high proportion of new energy,the cavitation characteristics of guide vanes and blades in hydropower units,especially pumped storage units under switch condition are quite different from stable condition,and the cavitation development mechanism is worthy of further study.This study examines the flows around a hydrofoil that oscillates in two different modes based on filter correction(FBM)and a Zwart-Gerber-Belamri cavitation model,focusing on the characteristics of flow cavitating evolution and the influences of different modes on the dynamic characteristics of cavitation.The numerical results of the cavitation shapes and velocity vectors around a NACA0015 foil are analyzed,the influencing mechanism of cavity evolution and the hydrodynamic parameters of its oscillating motions are explored.The results show that in the head fixed mode,foil oscillation induces larger cavities and a higher time-average volume fraction of vapor phase than the tail fixed oscillation,and the volume is larger.Under sheet cavitation in the two modes,the overall volume curves of vapor phase are very similar,while they are significantly different under cloud cavitation that differs in form.