Experimental studies of nozzle/diffuser micropumps using enhancement structure

This study conducts an experimental study concerning the improvement of nozzle/diffuser micropump design subject to enhanced structures. A total of three micropumps, including two enhancement structurs having two-fin or obstacle structure and one conventional micro nozzle/diffuser design. It is found that the pressure drops across the designed micro nozzles/diffusers are increased considerably when the obstacle or fin structure are added. The resultant maximum flow rates are 42.08 mm3/s and 50.15 mm3/s for conventional micro nozzle/diffuser and added two-fin structure in micro nozzle/diffuser operated at a frequency of 350 Hz. It is found that the mass flowrate for two-fin design surpasses that of conventional one when the frequency is below 400 Hz but the trend is reversed with a further increase of frequency. This is because the maximum efficiency ratio improvement for added two-fin is appreciably higher than the other design at a lower operating frequency. In the meantime, despite the efficiency ratio of the obstacle structure also reveals a similar trend as that of two-fin design, its significant pressure drop (flow resistance) had offset its superiority at low operating frequency, thereby leading to a least flowrate throughout the test range.