摘要
不同学者对液滴碰撞动力学的研究结论具有差异,研究的流体种类也较为单一。该文建立的研究体系包含了水、甘油水溶液、硅油、常温液态金属在内的9组流体,将流体黏度、表面张力的研究范围扩展至1~970 mPa·s、20~500 mN/m,通过相场法数值模拟,补充低Reynolds数Re的液滴碰撞数据,探索已有理论的适用性。研究表明:碰撞初期,铺展因子β随无量纲时间τ变化的已有理论主要适用于Re>100的情况。最大铺展因子β_(max)与Weber数We在毛细力区满足β_(max)∝We^(b),在黏性力区满足β_(max)∝Re^(b),与已有理论相符,壁面润湿性对指数b的影响具有规律。最小中心厚度h^(*)_(min)仅在We≥10时与已有理论h_(min)∝Re^(-0.5)相符;We<10时,h^(*)_(min)受到壁面润湿性和表面张力的明显影响。而当Re趋近于1时,β_(max)和h^(*)_(min)由液滴初始动能和壁面润湿性决定,偏离上述幂函数规律。
Previous research on droplet impact dynamics has yielded different results,and the types of fluids studied are not sufficiently diverse.This project numerically modeled droplet impact dynamics with nine kinds of fluids including water,glycerite,silicone oil,and liquid metals at room temperature with viscosities of 1-970 mPa·s and surface tensions of 20-500 mN/m.The phase-field model was used to supplement the data at low Reynolds numbers to explore the applicability of existing theories.The results show that at the beginning of the impact,the existing law for the spread factor,β,varying with the dimensionless time,τ,is applicable for Re>100.The simulation results are consistent with existing theory that the maximum spread factor,β_(max),scales as β_(max)∝We^(b) in the capillary regime and β_(max)∝Reb in the viscous regime.The effect of wall wettability on the exponent b was also analyzed.The minimum center thickness,h_(min)^(*),is consistent with the existing theory of h_(min)^(*)∝Re-0.5 only when We≥10.For We<10,the wall wettability and surface tension strongly influence h^(*)_(min).As Re tends to 1,β_(max) and h_(min)^(*) are determined by the initial kinetic energy of droplet and wettability of target surface,but they deviate from the above power function laws.
作者
杜宇轩
闵琪
李衍智
都家宇
DU Yuxuan;MIN Qi;LI Yanzhi;DU Jiayu(Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education,Collaborative Innovation Center of Advanced Nuclear Energy Technology,Institute of Nuclear and New Energy Technology,Tsinghua University,Beijing 100084*China)
出处
《清华大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2022年第2期294-302,共9页
Journal of Tsinghua University(Science and Technology)
基金
国家自然科学基金资助项目(51976104,51676113)。
关键词
液滴碰撞
流体性质
壁面润湿性
铺展因子
中心厚度
相场法
droplet impact
fluid properties
wall wettability
spread factor
central thickness
phase-field method
