Characterization of MEMS Pulsed Micro-Jets with Large Nozzles

In this paper, we present the first characterization of new pulsed microjets. The specificity of these new actuators is their large nozzle for MEMS device: the total exit cross-section on a single actuators can reach up to 3×3.28 mm

2

⋍ 10 mm

2

. Two different geometries are presented: one with a single slot and one with three slots on a single MEMS device. We measure the jet velocities as a function of the inlet pressure. Maximum jet velocity can reach up to 28 m/s with a pulsation frequency around 100 Hz. Other phenomena are discussed, like the deviation of the jet axis from the vertical and the wrong evaluation of the jet velocity close to the nozzle.We finally apply the three slots actuators to a backward-facing step flow and show a small reduction of the recirculation length when the pulsation frequency is equal to the shear layer frequency.