Cavitation Suppression In Piezoelectric Reciprocating Pumps

The piezoelectric pump reciprocating pump is a fluid transmission device that uses piezoelectric material as the energy conversion device to drive a reciprocating change of a pump chamber volume.At present,the actual output power and working efficiency of the piezoelectric reciprocating pump are generally low,and the advantages of high power density of the piezoelectric material when operating at high frequencies cannot be fully exerted.The main causes of this phenomenon is the occurrence of cavitation in piezoelectric reciprocating pumps during high frequency operation.In order to solve this problem,this dissertation combines the liquid working state of the piezoelectric reciprocating pump,starting from the working principle of the typical piezoelectric reciprocating pump,changing the distribution of the inlet and outlet valves,improving the working condition of the check valve and reducing the inertial mass in the inlet and outlet pipes.These three aspects have studied the suppression of cavitation.When the pressure in the flow field is lower than the saturated vapor pressure,the liquid medium will prone to cavitation.The presence of cavitation bubbles and cavities greatly reduces the performance and service life of the piezoelectric reciprocating pump,and even fails to work properly,which has become a problem for piezoelectric reciprocating pumps.In order to suppression the cavitation in the pump chamber of the piezoelectric reciprocating pump under the normal pressure,a new method to suppress the cavitation effect is proposed by increasing the number of inlet check valves.The simulation and experimental results show that when the ratio of the inlet and outlet valves is 6:2,the pressure in the pump chamber is higher than the saturated vapor pressure when the influent stage is working,which aims to suppress cavitation generation and improve the working efficiency of the pump.At the same time,we found that in the influent stage of the piezoelectric reciprocating pump,the check valve is also prone to cavitation.A PDMS check valve with a blocking member is studied,which can improve the deformation of the valve film in the original valve,thereby eliminating the low pressure region where cavitation is generated and improving the working efficiency of the piezoelectricreciprocating pump.Theoretical analysis and simulation results show that the problem of insufficient deformation of the original valve and causing cavitation due to low pressure at the gap has been solved.The experimental results show that the flow rate and output pressure of the piezoelectric pump while using the improved valve are significantly higher than the control pump using the original valve.When the driving frequency of the piezoelectric reciprocating pump is high,the liquid cannot be sucked in and discharged in time,and the pressure in the pump chamber will be lower during the influent stage,which will increase the cavitation.The piezoelectric hydraulic system can solve the cavitation problem by preset high pressure,but the liquid inertial mass in the pipeline will affect its working efficiency and prevent its working frequency from increasing.Through theoretical analysis of the liquid flow state in the pipeline,it is proved that a thin film vibration filter can be designed and installed at the connection of the check valve and the inlet/outlet pipes to reduce the influence of inertial mass.The simulation results show that when the volume of the vibration filter is small,the effect is proportional to its volume;but it will decrease after the volume exceeds a certain value.The calculation of the energy loss caused by the vibration filter also proves that the energy loss of the vibration filter is proportional to its size.It can be seen from the simulation results of the pressure distribution of the outlet pipe that the vibration filter can suppress the water hammer cavitation.Vibration filters of different sizes and mounting positions were tested using the piezoelectric pump test system.Experimental results show that the installation of the vibration filter greatly improves the pump output capability.The small and medium vibration filters tested have advantages in terms of output pressure or flow rate.The pump's output capability is optimal when the vibration filter is installed next to the check valve.