Research On The Valveless Piezoelectric Pump With Raindrop-shaped Tubes

The structure of valveless piezoelectric pump is very simple and has no electromagnetic interference.So it has broad application prospects in microelectromechanical systems such as biochemical analysis,fluid transportation and chip cooling.With the development of technical equipment,the reliability,stability and flow control accuracy of valveless piezoelectric pump are increasingly required.The valveless piezoelectric pump represented by conical flow tube has many problems,such as small flow,large turbulence,low output pressure and serious reflux,among which turbulence is the main cause of energy loss.Study the coupling action law between pump medium and volume chamber wall under the action of piezoelectric vibrator,and construct geometric shape of the volume chamber which is in favor of the single phase flow,reduce the energy loss caused by the turbulence are basic work of the valveless piezoelectric pump to be commercialized and practiced.The shape of raindrop is the result of combined action of gravity,surface tension,air drag and buoyancy when it is landing in the air.It is essentially a state of balance between surface force and physical force.The liquid in the piezoelectric pump finally obtains the unidirectional flow under the action of inertia force,tangential force and flow resistance.In essence,it is also the balance between physical force and surface force.If the cavity is made into the shape of the raindrop,it is possible to obtain uniform force between liquid and wall,reduce turbulence intensity,thus reduce energy loss.Follow the idea,the Project Group puts forward a valveless piezoelectric pump with raindrop-shaped tubes.The main research contents include:(1)According to the inherent characteristics of the raindrops,a type of valveless piezoelectric pump with raindrop-shaped tubes is innovatively proposed and its working principle is analyzed and vibration analysis is conducted on the piezoelectric vibrator.(2)The modal analysis of the piezoelectric vibrator is carried out and the vibration frequencies and the amount of demoration are analyzed.(3)Finite element analysis of the flow field in the pump is conducted and obtained the pressure distribution and velocity vector graph.Based on the fromer result,the flow characteristics of the valveless piezoelectric pump with raindrop-shaped tubes is recognized.(4)Based on the idea of raindrop-shaped tubes,a valveless piezoelectric pump with raindrop-shaped tubes was designed and manufactured.The effects of voltage and frequency on the performance of the valveless piezoelectric pump with raindrop-shaped tubes were experimentally studied.On the one hand,the flow direction of the pump is verified.On the other hand,the way of the pressure difference in pump’s inlet and outlet and flow rate of the pump varying with driving frequency and driving voltage are obtained.To sum up,the valveless piezoelectric pump of the raindrop-shaped tubes has a simple structure and is easy to integrate and miniaturize,which can not only transfer the fluid,but also realize the fluid mixing function.Therefore,it can be used for conveying fluid,fluid heat dissipation and fluid mixing.