| Because of its compact structure,simple and easy to be miniaturized and free from electromagnetic interference,valveless piezoelectric pump has a great development prospect in drug delivery,chip cooling,cell handling,medical atomization and other industries.After decades of research,although the valveless piezoelecteic pump with conical flow tube has the most industrial prospect,the current valveless piezoelectric pump with conical flow tube still has the disadvantages of low transport stability,single flow trend and so on,which leads to vortex reflux and limits its application in the occasions with high flow stability requirements.Therefore,strengthen the research of valveless piezoelectric pump,improve the transmission quality of valveless piezoelectric pump,solve the single flow trend which leads to vortex,turbulence and boundary layer separation,expand the application field of valveless piezoelectric pump,it will greatly promote the microfluidic technology,polymer and the drug delivery technology,electronic chip cooling technology and other related high-tech industry development.The project was funded by the national natural science foundation of China(No.51375227)and the key research project of GuangZhou education bureau(No.1201610315).In this study,a valveless piezoelectric pump with streamlined flow tube is presented,and the research around pumping mechanism,flow field characteristics,flow field direction and pumping capacity test.According to the phenomenon that the streamlined structure in the natural world is subject to less resistance when moving in the fluid,a valveless piezoelectric pump with streamlined flow tube is proposed to change the single flow trend and thereby improve the pumping quality and stability.In this study,the feasibility and performance of the valveless piezoelectric pump with streamlined flow tube are proved from theoretical analysis,simulation and experimental verification,which provide the research foundation for the development and application of this type of valveless piezoelectric pump.The main contents of this paper are as follows:(1)Pump structure design.This paper mainly designs the structure of streamlined flow tube and valveless piezoelectric pump.According to the movement characteristics of the streamlined structure in the fluid,the streamlined structure design method is used to complete the structure design of the streamlined structure and determine its structural parameters.The mathematical relationship between the boundary layer separation conditions and the flow tube structure is constructed.(2)Theoretical analysis.Frist,it is proved that the streamlined flow tube has the characteristics of flow resistance difference when flowing in the positive and negative direction by theoretical.Then,giving the expression of flow resistance coefficient,and establishing the mathematical relationship between the pump flow rate expression and the parameters such as frequency,voltage and flow resistance.According to the above,the pump performance is proved theoretically.(3)Finite element simulation.The flow field in the pump is simulated by finite element method.It is verified that the theoretical analysis is correct to predict the change of flow field pressure,that the streamlined flow tube has the characteristics of flow resistance,and that the internal vortex and turbulence are improved.The simulation proves that the valveless piezoelectric pump with streamlined flow tube has pumping capability and verifies the correctness of the theoretical analysis.(4)Experimental analysis.Prototypes were fabricated using 3D printer technology,and experiments were conducted on fluid flowing from the forward and reverse directions through the flow tube,proving that there is a difference in flow resistance between forward and reverse flows.Through the experiment of piezoelectric vibrator and pumping flow rate,the relationship between vibration and flow rate is further analyzed,and the experimental results are compared with the simulation,which proves the correctness of the simulation.The feasibility of valve piezoelectric pumps streamlined flow tubes is comprehensively explained.(5)Comparative studies.First,the design and processing of a number of different angle parameters of the streamlined flow tube and its valveless piezoelectric pump.Then,the regional dynamic simulation model of the whole pump flow field is established by simulation and experimental research.Finally,the relationship between performance and angle is analyzed,and the application of valveless piezoelectric pump with different parameters is given.In conclusion,this paper proves that the valveless piezoelectric pump with streamlined flow tubes have the characteristics of flow resistance and pump effect from three aspects: theory,simulation and experiment.The essential reason that valveless pressure pump of streamlined flow tube can change the flow trend to avoid boundary layer separation and improve turbulence and vortex is analyzed. |
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