Simulation And Experimental Study Of Valveless Piezoelectric Pump With Tapered Step Tubes

Valveless piezoelectric pumps have the advantages of small size,compact and reliable structure,low power consumption,no leakage pollution and noise,easy integration and control,as well as high stability,high accuracy,and high response speed.It has great promise in industries such as biochemistry,fuel cells,liquid cooling and precision drives.In microfluidic systems,valveless piezoelectric pumps do not cause damage to macromolecular biological materials or active cells compared to valved piezoelectric pumps.The conical flow tube valveless piezoelectric pump has a more far-reaching research background and a simple and stable structure with industrialization prospects,but its use in high stability flow applications is limited by the small difference in flow resistance of its forward and reverse flow structure,which makes its flow delivery low,and the current conical flow tube valveless piezoelectric pump is mostly assembled in a three-dimensional structure,which will increase the probability of fluid leakage and is affected by the gravity effect in pumping work.This paper proposes a tapered step flow tube valveless piezoelectric pump for improving the difference between positive and negative flow resistance during pumping,based on the frictional dissipation effect of gravity and step surface when the fluid is passed through the step overflow dam in a positive direction,thus improving the pumping quality and enhancing stability.The paper focuses on theoretical analysis,simulation and experimental validation to jointly demonstrate the feasibility of using a conical stepped flow tube valveless piezoelectric pump and to investigate its performance.The results of this study show that this type of valveless piezoelectric pump can significantly improve the pumping quality and enhance the stability of fluid delivery.This research therefore provides an important research base for the development and application of this type of valveless piezoelectric pump.The main research elements are as follows:(1)Piezoelectric vibration analysis.Firstly,the operating characteristics and principles of the piezoelectric oscillator,an important driving device in a valveless piezoelectric pump,were analyzed,and then a 4th order modal analysis of the piezoelectric oscillator was carried out in computer finite element simulation software.It was learned that the oscillation shape of the firstorder mode of the oscillator is most suitable for the operation of the piezoelectric oscillator.(2)Structural design and theoretical analysis,for the conical stepped flow tube valveless piezoelectric pump for structural design,according to the fluid in the stepped structure of the motion characteristics,and then according to the fluid mechanics’ theory analysis to prove the conical stepped flow tube forward and reverse flow with flow resistance difference characteristics,to establish the pumping flow expression.(3)Finite element simulation,finite element simulation of the flow field inside the pump,to obtain the simulation of the conical stepped flow tube under different pressure difference outflow data,through the analysis of the data,verify the conical stepped flow tube has flow resistance difference characteristics,in the conical stepped flow tube valveless piezoelectric pump modeling simulation,change the parameters in the observation of the flow field internal pressure and velocity clouds,analysis to learn the parameters on the output performance of the conical stepped flow tube.(4)A prototype was machined and fabricated using computer-aided manufacturing technology,and a comparison experiment was conducted between the output flow rate of the conical stepped flow tube valveless pump and the no/single stepped conical flow tube valveless piezoelectric pump.At a frequency of 18 Hz and a drive voltage of 180 V,the output flow rate of the conical stepped flow tube valveless piezoelectric pump was 8.04 m L/min,which was 29% higher than the maximum flow rate of the no stepped conical flow tube valveless piezoelectric pump This demonstrates the strengthening effect of the stepped structure on the flow resistance difference of the tapered flow tube.The relationship between each parameter and the flow resistance difference was further analyzed through several sets of flow experiments with different parameters of the valveless pump,and the experimental results were compared with the simulation to prove the correctness of the simulation.