床面颗粒临界起动时受力的脉动特性  

Turbulence Characteristics of the Bed Particles at Critical Incipient Movement

作　　者：王兴奎[1] 安凤玲[1] 任裕民[1] 杨铁笙[1] 

机构地区：[1]清华大学水利水电工程系

出　　处：《泥沙研究》1993年第3期104-116,共13页Journal of Sediment Research

基　　金：国家自然科学基金

摘　　要：本文通过试验研究了不同比重的颗粒在临界起动时的受力特性,当颗粒处于临界起动状态时,时均上举力只有颗粒水下重量的0.646倍,但需要有6.7％的瞬时上举力大于颗粒的水下重量,说明只有当大于颗粒水下重量的瞬时上举力持续一定的时间时,颗粒才能起动。脉动力的脉动强度与时均力具有相同的数量级,即脉动力对泥沙运动具有重要的作用。脉动力的概率密度近似为正态分布;自相关系数的衰减速度比流速的衰减速度更慢,最大互相关系数有一个滞后时间;脉动力的能谱密度分布比流体的频率更低。When the ratio of the time-average lift force to the submerged weight of the particle is 0.646 and that the instantaneous lift force is larger than that of the submerged weight by 6.7%, the particle is at critical incipient movement.The turbulent intensity of the lift force is 0.434 of the mean life force. The tur bulent intensity of the drag force is 0.95 of the mean drag force. So the turbulence is very important for the movement of bed particale. The turbulent force acting on bed particle is normally distributed. Its energy frequency is lower than that of water flow.

关 键 词：河床 泥沙颗粒 临界起动 受力 脉动 

分 类 号：TV147.3[水利工程—水力学及河流动力学]