Numerical Simulation And Experimental Study Of Double-Chamber Serial Valveless Piezoelectric Micropump Based On Coanda Effect

Micropumps play a vital role in the micro-fluid-systems,of which the performance directly determines the holistic capability.Plenty of applications have been realized in different domains of science and technology,including drug detection,biomedicine,lab-on-a-chip system and microelectronic chip cooling systems etc.Among the developed micropumps,the valveless piezoelectric micropumps based on the inverse piezoelectric effect of special material have been widely investigated since they have many advantages,such as small size,low power consumption,no risk of valve wear and fatigue.In this paper,according to the valveless piezoelectric micropump based on Conda effect,a novel double-chamber serial valveless piezoelectric pump based on Conda effect is proposed,which has compact structure and better performance.The novel double-chamber serial micropump integrates two wall-attached jet elements together,through the cooperation of the two pump chambers,the micropump can discharge fluids during the 80% working period.The following are the main research contents and results of this paper:1.Based on the Coanda effect,a novel serial valveless piezoelectric micropump with double chambers is proposed,and the theoretical basis and working principle of the pump are expounded.The vibration model of the vibrator proposed by Bu is adopted,the volume efficiency of the serial micropump and the formula for calculating the Reynolds number are derived.The piezoelectric micropump samples for characteristic experiment are processed by silicon-based MEMS technology,and the main process methods in the sample pump processing were introduced,including the processing of the mask,the silicon-based lithography and etching,and the bonding of the glass plate and the silicon.2.The performance of the three different structure valveless piezoelectric micropump samples based on Conda effect(P1,P2 and P3),under the driving voltage of 75vpp~200vpp and excitation frequency of 25Hz~250Hz were studied.Theexperimental results show that whether the single-chamber valveless piezoelectric micropump based on Coanda effect or the out-of-phase double-chamber serial piezoelectric micropump has the same net flow rate,When the excitation frequency is constant,the net flow rate increases with increasing voltage.When the driving voltage is constant,the net flow of the valveless piezoelectric micropump based on Conda effect with single or double chambers tends to increase first and then decrease with the increase of frequency,When the driving voltage is 200 vpp,the optimal driving frequencies of the single and double chamber valveless piezoelectric micropumps based on Conda effect are 60 Hz and 50 Hz,and the net flow rate is 0.735 ml/min and1.062 ml/min,respectively.The performance of the double-chamber serial valveless piezoelectric micropump based on Conda effect in anti-phase operation(the phase shift of the two-vibrator is 180 °)is significantly higher than that in the in-phase operation(the phase shift of the two-vibrator is 0°),and When the two chambers are working in phase,the micropump will show a reverse suction under the certain driving conditions.When the jet angle ? of the valveless double-chamber serial piezoelectric micropump based on Conda effect is increased,the net flow rate will increase significantly,but the optimal excitation frequency will also increase.Under the 200 vpp out-of-phase drive voltage,the corresponding excitation frequencies for P2(?=30 °)and P3(?=45°)at maximum net flow are 50 Hz and 75 Hz,respectively.3.The performance of the valveless double-chamber serial piezoelectric micropump based on Conda effect was simulated by SST turbulence model and velocity boundary conditions.The flow characteristics of the serial valveless piezoelectric micropump under different driving phase shift are compared.The results show that the net flow of the micropump is the largest when the two vibrators are operated at 180°phase shift.When the Reynolds number Re=500 and the frequency f=50Hz,the net flow of the anti-phase operation is 0.955ml/min,nearly three times as the vibrators working in-phase.Under the same speed boundary condition,the net flow of the valveless double-chamber serial piezoelectric micropump based on Conda effect(the two vibrators working anti-phase)is higher than that of the single-chambervalveless piezoelectric micropump,but the efficiency of the double-chamber serial micropump is lower than that of a single chamber.In terms of back pressure performance,the advantage of the valveless double-chamber serial piezoelectric micropump based on Conda effect is obvious.From the numerical simulation results,it can be seen that the valveless double-chamber serial piezoelectric micropump based on Conda effect has better performance under high Reynolds number and low frequency conditions.