Investigations on performance of valveless piezoelectric micropump with concave tuning diffuser/nozzle elements in transient flow

Abstract

A diffuser/nozzle is one of the most frequently-used channels in a valveless piezoelectric micropump, but its efficiency has not been satisfactory. Hence, optimisation of the channel structure is of great significance. The concave tuning diffuser/nozzle element can obtain steady flow rectification under different Reynolds numbers, and its efficiency is much higher than the conventional diffuser/nozzle element whose diverging angle is >25°. Therefore, the application of concave tuning on the micropump is promising and worth anticipating. In this work, the experiment and numerical simulation were carried out under the conditions of voltage (50-250 vpp), excitation frequency (10-1000 Hz) and Re c (100-1000). The results show that the performance of a micropump with concave tuning is better than that with a straight sidewall, as the pump efficiency is improved significantly. The position and size of vortexes are of great significance to the pump efficiency of the micropumps. The distribution of pressure in the micropumps with concave tuning and straight sidewall was displayed. With the increase of characteristic Reynolds number, the adverse pressure gradient occurred. Compared with the straight sidewall, the concave tuning structure can better withstand adverse pressure gradient and delay the boundary layer separation in the channel.

A Theoretical and Experimental Study of a Piezoelectric Pump with Two Elastic Chambers

“…Equation (22) shows that the elastic chamber almost eliminates the influence of driving frequency f and the liquid mass on the dynamic load. When the piezoelectric pump has high driving frequency f and small elastic stiffness (k f2 and k f3 ), we can obtain F 1 << F 1 .…”

“…The third aspect is that some local structures of the piezoelectric pump weaken the high-frequency output performance. For example, the structure and volume of the pump chamber, the structure of the valve hole, and the diameter of the pipeline all have an important influence on the high-frequency output performance of the piezoelectric pump [ 20 , 21 , 22 ]. The problem of structure weakening high-frequency performance is particularly prominent in valveless piezoelectric pumps.…”