Analysis of transient flow characteristics in flat diffuser/nozzles

• Published in: 2014 ISFMFE - 6th International Symposium on Fluid Machinery and Fluid Engineering p. 079
• Main Authors: He, Xiuhua, Zhu, Jiawei, Zhu, Xuebin, Yang, Song
• Format: Conference Proceeding
• Language: English
• Published: Stevenage, UK IET 2014; The Institution of Engineering & Technology
• Subjects: Applied fluid mechanics; Flows in ducts, channels, and conduits; Fluid mechanics and aerodynamics (mechanical engineering); General fluid dynamics theory, simulation and other computational methods; Jets in fluid dynamics; Mechanical components, systems and devices; MEMS and NEMS device technology; Nozzles; Numerical analysis; Numerical approximation and analysis; Other numerical methods; Rotational flow, vortices, buoyancy and other flows involving body forces; flow simulation; transient flow characteristics; excitation frequency; phase difference; pressure loss coefficient; jets; tube efficiency; Womersley number; Reynold number; pipe flow; flat diffuser-nozzle tubes; wall-attached jet; numerical analysis; piezoelectric micropumps; Coanda effect; vortices; micropumps; diffuser angle; vortex existence time; nozzles; pipes; numerical simulation
• ISBN: 9781849199070; 1849199078
• DOI: 10.1049/cp.2014.1203

Transient flow characteristics in piezoelectric micropumps with flat diffuser/nozzle tubes were studied by numerical simulation. There is phase difference between velocity and pressure at high frequency. The effect of Reynold number, diffuser angle and excitation frequency on phase difference was studied. Pressure loss coefficient and tube efficiency were discussed as Womersley number ranging from 0.24 to 1.50.The existence time of visible vortexes in chambers decreases with the increasing of frequency. The tube efficiency of Re = 200 and f = 10 Hz reaches maximum when is 12°. The phenomenon of wall attached jet in the diffuser/nozzles at high Reynold numbers and low frequencies is paid attention to. When the frequency is greater, the Coanda effect disappears.