基于附壁效应的无阀压电泵研究

摘要

A valveless piezoelectric micropump applying Coanda effect has been developed.The dynamic mesh method and numerical simulation were applied for studying the fluid field and performance of micropump.The results show that due to the Coanda jet,the volume efficiency ηof the micropump was able to reach over 0.5 at zero pump pressure,which was larger than the traditional diffuser/nozzle valveless micropump.The effect of the flat cone tube and the concaved surface was discussed and the results show that the length of flat cone tube must be larger than dcot(θ/2),and when c2/c1 =1,L1/d =9,the flowrate of micropump reaches a maximum at zero pump pressure.And the comparison of η with the different c2/c1 and pump pressures shows the large width of the concaved surface could enhance the performance of micropump at a high pump pressure,but reduce the performance of micropump at a low pump pressure.Response surface methodology was utilized to optimize the structural parameters.When the pump pressure was 5 kPa,the recommend region was 4≤L1/d≤5 and 0.75 ≤c2/c1 ≤0.85.When L1/d =4.3 and c2/c1 =0.80,the maximum volume efficiency was 0.323 and the difference was 1.89％ comparing with the value of simulation which was 0.317.%提出一种基于附壁效应的无阀压电泵,该泵利用附壁射流元件造成吸入过程和排出过程中进出口的流量差,实现流体输送.首先通过动网格技术及数值模拟研究微泵的内部流场和外特性,结果表明该无阀压电泵的容积效率η可以达到0.5以上,高于传统扩散/收缩管无阀压电泵.然后讨论了平面锥管长度和两分流直管间凹劈面宽度对微泵性能的影响,平面锥管长度L1必须大于d cot(θ/2),当c2/c1=1时L1/d=9的微泵在零输出压力下流量最大;不同输出压力和c2/c1的微泵流量对比表明凹劈面宽度越宽微泵输出压力性能越佳,但是在低输出压力下微泵随着凹劈面宽度的增加其容积效率降低.最后应用响应面方法对平面锥管长度和凹劈面宽度进行优化,结果表明当输出压力为5 kPa时,最优的参数选取范围为4≤L1/d≤5,0.75≤c2/c1≤0.85,当L1/d=4.3,c2/c1=0.80时η达到最大,为0.323.其数值模拟为0.317,相差1.89％.