Valveless piezoelectric pump with HBSS of 180 degree splitting angles: (a) pump body, (b) assembled prototype. Source: Guilin University of TechnologyResearchers from the College of Mechanical and Control Engineering, Guilin University of Technology, Guilin, China, have built a 3D-printed prototype of a valveless pump capable of delivering fluids via the inverse effects of piezoelectric vibration.

To accomplish this, the team modified the splitting angle of the hemisphere-segment bluff body (HSBB).

“In the process of reciprocating motion of vibrator, the equation of paraboloid surface is utilized to simulate the deformation of vibrator for convenient calculation since the deformation surface of first-order vibration is similar to paraboloid of revolution,” explained the researchers.

“Supposing the initial state of piezoelectric vibrator is at horizontal position when t = 0 and starts to move upward. The vibration amplitude at each point for piezoelectric vibrator keeps invariant.”

According to the researchers, performance of flow relies on the difference between positive and negative directions in flow resistance.

“The bluff-body resistances in the flow field include fiction and shape resistance. The shape resistance plays a dominant role in piezoelectric pump due to common laminar flow state in the chamber,” the researchers added.

Once simulation models were constructed, the research team measured the flow velocity and pressure of the prototypes.

“For all pumps with HSBB of different splitting angles, the vortex of positive flows between HSBB are larger than that of negative flows, and the velocity of positive flows on the outlet are obviously greater than that of negative flows on the outlet. Moreover, the velocity difference between positive flows and negative flows on the outlet firstly increases and then decreases, suggesting that the proper enlargement of splitting angle can facilitate the unidirectional flow. Besides, for all pumps with HSBB of different splitting angles, the pressure difference between the inlet and outlet of positive flows are less than that of negative flows,” explained the authors.

“The simulation and experiment results on the flow resistance of different pumps suggest that the valveless piezoelectric pump with HSBB of 210° splitting angle exhibits the best flow transportation performance, which is a promising candidate for various flow delivery applications.”

The research appears in an article titled Improved design and experimental analysis of valveless piezoelectric pump based on hemisphere-segment bluff-body.