Regular valveless piezoelectric pumps have rectifying elements outside their chambers to produce net flow.These rectifying elements outside the chamber will increase the overall volume of the pump and prevent its minimization.Valveless piezoelectric pump with unsymmetrical slopes elements(USE),proposed in this paper,differs from other valveless pumps in that it is easy to be minimized by developing the chamber bottom as such a rectifying element.In this research,the working principle of the proposed pump was analyzed first.Numerical models were thereby established and numerical simulation was conducted to the chamber flow field with the method of time-dependent velocity.The effects of the USEs on the flow field in the chamber were shown clearly in simulation.And the particular feature of flow field in the chamber was discovered.It behaves a complex flow field,in which strong turbulent occurs companying a lot of vortexes in different directions and different sizes.This feature is just opposite to what regular piezoelectric pumps expect:a moderate flow field.The turbulent flow could be used to have different liquids stirred and well mixed in the chamber to produce homogeneous solution,emulsion or turbid liquid.Meanwhile,numerical simulation also presents the effect of the angles difference of the two slopes upon the flow field,and upon the flow rate of the pump,which fits to the theoretical analysis.Experiments with the proposed pump were also conducted to verify the numerical results.In these experiments,six USEs with different slope angles were used for efficiency tests,which proved the validity and reliability of the numerical analysis.The data obtained from numerical analysis agree well with that from the experiments.The errors ranged from 4.4% to 14.8% with their weighted average error being 9.7%.
无阀压电泵需要外接用于产生单向流动流管,阻碍了压电泵的微小型化,针对这一缺点提出了非对称坡面腔底无阀压电泵,该压电泵将用于产生单向流动的部件——非对称坡面集成于泵腔的底部。对非对称坡面腔底无阀压电泵进行了计算机建模,基于商用Fluent12软件运用自定义函数(user defined functions,简称UDF)对压电振子运动形式进行了模拟;采用RNGκ-ε湍流模型对瞬态N-S方程进行了求解,分析了泵腔内流场;得出了从20°到70°不同坡面角度下的平均流量,在坡面角为20°时,可以得到最大平均流量为0.864 ml/min,并通过流量测量试验测得该泵的最大流量达到了8.6 ml/min。从仿真和试验的角度验证了该泵的可行性。
