中文摘要：

基于热汽泡生长和冷凝为微泵提供泵送压力源以及扩张管/收缩管流动阻力特性不同而实现差量流动的原理,对不同加热时间比例、驱动频率以及不同扩张角度及功率下热汽泡驱动无阀微泵流动特性进行了研究。蒸发和凝结过程通过流体体积函数（VOF）两相流模型及用户自定义函数（UDF）接口实现。结果表明：相同加热时间比例下,随着驱动频率增加,微泵泵送流量呈先增加后降低趋势;加热时间比例为10%,驱动频率为250Hz时泵送流量达到最大值5.87μL/min;在保持微泵扩张管/收缩管长宽比不变的情况下,泵送流量随扩张角也有先增后减的趋势,并在扩张角为14°时泵送流量达到最大,扩张管/收缩管压差也较大;在整个驱动周期内扩张管方向颈部平均流速总是大于收缩管方向颈部平均流速;泵送流量随加热功率增加呈先增加后趋于平缓的趋势。

英文摘要：

Based on the different flow resistance characteristic of diffuser/nozzle at the bubble growth and condensation stage, the flow characteristics of thermal-bubble actuated valveless micropump under different ratio of heating, driving frequency and diverging angle and different heating power are numerically investigated. Evaporation and condensation processes are accomplished by Volume of Fluid （VOF） multiphase flow model and User Defined Functions （UDF） interface. The results reveal that with the same ratio of heating time, the volume flow rate increases at first and then decreases with the increasing driving frequency. The micropump has a maximum flow rate of 5.87 μL/min when the driving pulse is 250 Hz at 10% heating ratio. The volume flow rate increases at first then decreases with the enlarging diverging angle when keeping the aspect ratio constant, and it will reach the maximum when the diverging angle is 14°, and it has a higher pressure difference between the diffuser and the nozzle. The average velocity at the diffuser neck is always greater than the nozzle during the entire driving period, the pumping flow rate presents a trend of increasing at first and then flatting with the increasing heating power.