高能超声分散纳米晶须的数值和物理模拟

Numerical and Physical Simulations of Nano-whiskers' Dispersion Under High Intensity Ultrasonic

为研究高能超声处理制备纳米复合材料过程中纳米增强相在熔体中的分散过程,采用甘油为介质分别进行了数值模拟以及物理模拟。数值模拟结果表明,当超声作用于甘油中时,甘油中会形成中心-底面-壁面-中心的环形流动,变幅杆探头端面边缘附近甘油流体存在最大的流动速度,且随着超声功率的增大,流体运动速度增大。物理模拟实验结果显示,高能超声作用下甘油的实际运动行为与数值模拟结果相符合,存在环形流动;此外,高能超声作用下甘油中存在明显的空化效应;纳米晶须在超声作用下于甘油中分散良好,且随着超声功率的增大,达到充分分散所需时间变短。

High intensity ultrasonic processing is a good way to fabricate nano-composite.In order to study the dispersion process of nano-whiskers under high intensity ultrasonic,numerical and physical simulations of nano-whiskers’ dispersion under high intensity ultrasonic were carried out by using glycerol as fluid medium.The numerical simulation results show that ultrasonic forces the fluid to flow along the center line-bottom-wall-center line route and flow velocity is the maximum near the probe tip edge.Besides,the flow velocity increases with the increase of ultrasonic power.The physical simulation results are in good agreement with the numerical simulation results.In addition,cavitation as well as convection is found in the glycerol during the ultrasonic processing;the nano-whiskers are dispersed well in the glycerol under ultrasonic,and the time for fully dispersion decreases with the increase of ultrasonic power.