Aspects of stationary and dynamic micro diffuser flow

The crucial points of micro diffuser flow, resulting from empirical and theoretical investigations, are presented. The central figure of merit for micro pump application is the rectification efficiency ε. It mainly depends on the aperture angle, relative diffuser length, flow velocity, and (pump) frequency. The highest (i.e. best) |ε|-value possible is around 0.25…0.4. The theoretical approach is mainly based on general investigations of energy conversion and experimental data from classical hydraulics. It matches the fluid dynamic behaviour of tested micro diffusers fairly well