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

• Published in: Micro & nano letters Vol. 14; no. 7; pp. 765 - 770
• Main Authors: He, Xiuhua, Shi, Jiawei, Yang, Hang, Lin, Nan, Uzoejinwa, Benjamin Bernard
• Format: Journal Article
• Language: English
• Published: Stevenage The Institution of Engineering and Technology 26.06.2019; John Wiley & Sons, Inc
• Subjects: adverse pressure gradient; boundary layer separation; boundary layers; channel flow; characteristic Reynolds number; Computational fluid dynamics; Computer simulation; concave tuning diffuser/nozzle element; concave tuning structure; Diffusers; diverging angle; Efficiency; Flow separation; flow simulation; Fluid flow; frequency 10.0 Hz to 1000.0 Hz; microchannel flow; Micropumps; Nozzles; numerical analysis; numerical simulation; Optimization; piezoelectric devices; Piezoelectricity; pressure distribution; pump efficiency; Reynolds number; Simulation; Steady flow; steady flow rectification; straight sidewall; Stress concentration; transient flow; Tuning; Unsteady flow; valveless piezoelectric micropump; vortexes; vortices; concave tuning diffuser/nozzle element; flow simulation; valveless piezoelectric micropump; channel flow; boundary layer separation; frequency 10.0 Hz to 1000.0 Hz; concave tuning structure; numerical analysis; straight sidewall; piezoelectric devices; steady flow rectification; pump efficiency; numerical simulation; transient flow; vortexes; pressure distribution; diverging angle; boundary layers; characteristic Reynolds number; microchannel flow; flow separation; adverse pressure gradient; vortices; micropumps; nozzles
• ISSN: 1750-0443; 1750-0443
• DOI: 10.1049/mnl.2018.5712

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 Rec (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.