Research On Valve-Less Piezoelectric Pump With Half-Cylinder Bluffbody In Conical Cavity

Valve-less piezoelectric pump has broad application prospects in drug delivery,fuel supply,water cooling and heat dissipation,agricultural drip irrigation and other fields because of its advantages of small size,simple structure and controllable flow.Most of the existing valve-less piezoelectric pumps with pipelines are complex three-dimensional structure,which is not conducive to the miniaturization of the pumps.The valve-less piezoelectric pump with triangular-prism bluffbody(VPTB pump)is a simple valve-less piezoelectric pump with built-in plane pipeline,but it has the problem of small output flow,which limits its application in the field of large flow demand.In order to improve the output flow rate of the pump,combined with the coanda effect of the cylindrical surface of the half-cylinder bluffbody and the unequal flow resistance characteristics of the conical cavity,a valve-less piezoelectric pump with half-cylinder bluffbody in conical cavity(VPHBCC pump)was proposed.The influence of the half-cylinder bluffbody and the conical cavity on the output performance was discussed,respectively,and the structural parameters were further optimized.The main work contents are as follows:1.In order to investigate the influence of half-cylinder bluffbody on output performance,a valve-less piezoelectric pump with half-cylinder bluffbody(VPHB pump)was designed based on the structural characteristics of VPTB pump.The flow state in the pump chamber of the VPHB pump was numerically simulated by ANSYS software,and the flow resistance characteristics of the pump and the VPTB pump were compared and analyzed.The prototypes of two pumps were made and the flow and pressure difference tests were carried out.The results show that the VPHB pump can realize unidirectional fluid transport,and the transport efficiency is improved by20.00% compared with the VPTB pump.Under the 220 V driving voltage,the maximum output flow(12.28g/min)and output pressure difference(17.3mm)of the VPHB pump are better than the VPTB pump.2.In order to investigate the influence of conical cavity on output performance,a VPHBCC pump was designed based on VPHB pump.The instantaneous flow process in the pump chamber of the VPHBCC pump was simulated and analyzed.The flow resistance characteristics of the pump and the VPHB pump were compared and analyzed.Two kinds of pump prototypes were made and tested.The results show that the VPHBCC pump has the characteristics of unidirectional fluid transport,and its transport efficiency is 29.71% higher than that of the VPHB pump.Under the 220 V driving voltage,the maximum output flow(30.96g/min)and output pressure difference(40.16mm)of the VPHBCC pump are greatly improved compared with the VPHB pump.3.In order to optimize the structure of the VPHBCC pump,the flow resistance characteristics and flow state of different half-cylinder diameter(2mm,2.5mm,3mm,3.5mm,4mm)and different conical cavity taper angle(1°,3°,5°,7°,9°)were simulated and analyzed.The pump prototypes of the half-cylinder diameter group and the conical cavity taper angle group were made and tested.The results show that when the diameter of the half-cylinder is 3.5mm and the taper angle of the conical cavity is 5°,the efficiency of the pump is the highest.Under the driving voltage of220 V,the pump with the half-cylinder diameter of 3.5mm and the taper angle of 5°has the optimal maximum output flow and output pressure difference,which are30.96g/min and 40.16 mm,respectively.This study provides a certain reference for the development of valve-less pump with small volume,simple structure,convenient processing and high output performance.