超声行波微流体驱动的流动特性分析

Flow Characteristics Analysis of Ultrasonic Traveling Wave Micro-fluid Driving

研究了超声行波驱动圆环模型的流动特性与影响因素.通过模态分析确定了模型的最佳驱动方式;通过谐响应分析和瞬态分析得到圆环形微管道内壁的振动位移分布以及行波运行情况;通过流固耦合分析得到微管道内流体的瞬时流动速度、时间平均速度以及各种参数对流动特性的影响.结果表明,圆环模型能在管道壁面产生较规则的行波从而推动管内流体流动.微管道内瞬时速度为正弦脉动量,时间平均速度为非对称的抛物线结构.该抛物线结构的形状受驱动频率的影响较大而受驱动电压影响较小,形状发生改变的频率范围在2kHz—2.5kHz之间.流体平均速度随粘度的增加而降低,首次发现流体粘度在0.07Pa.s时近壁开始出现反向流.此外,分析还发现耦合面结构对流体平均速度有较大影响.

Flow characteristics and influencing factors in a ring model based on ultrasonic traveling wave driving were investigated. The best model driving approach was determined through modal analysis. The micro-vibration displacement distribution of the fluid-structure-interface was obtained through harmonic response analysis and the traveling wave propagation was observed through transient analysis. Through fluid structure coupling analysis, the transient and the timeaveraged velocity were computed and the influencing factors on the velocity were discussed. The results indicated that regular traveling wave could be generated in the ring model with proper configuration. The transient velocity in the channel was sine shape and the time-averaged velocity profile was asymmetric parabolic shape. This parabolic shape was influenced by the driving frequency obviously. When the frequency was about 2000Hz to 2500Hz, the shape began to change. At the same time the driving voltage had little impact on it. The time-averaged velocity decreased with the viscosity increasing. As the fluid viscosity reached to 0.07Pa ·s, the reverse flow appeared. The structure of the coupling surface also had obvious influence on the time-averaged velocity.