Abstract: Most piezoelectric pumps employed in water cooling systems contain internal valves which increase the volume of the systems, affect the reliability of the pump, and cause noise. As valveless piezoelectric pump with fractal-like Y-shape branching tubes has simple processing characteristics of 2.5 dimensions, and multi-leveled braching flow can cover larger area which produces excellent heat dissipation, which can avoid shortcoming of traditional valve piezoelectric pump. Structure and working principle of valveless piezoelectric pump with fractal-like Y-shape branching tubes are introduced. Then, flow resistance characteristics of fractal-like Y-shape branching tube is analyzed by using fractal principle. Meanwhile, finite element software is employed to simulate the flow field of the pump, and the relationships between pressure drop and flow rate in inlet and outlet of this pump are obtained. Valveless piezoelectric pumps with fractal-like Y-shape branching tubes are fabricated, and flow resistance and back pressure experiments are conducted. The experimental results show that, the export flow rate along dividing flows is larger than merging flows at the same pressure drop. The maximum relative error between experimental and simulated results occurs, when pressure drop between inlet and outlet is 196 Pa, which is 90% and 89% along dividing and merging flows respectively. And the maximum back pressure of the valveless pump is 637 Pa under 100 V (9 Hz) power supply. The proposed researches ensure that flow resistances between merging and dividing flows are unequal and also validate the feasibility of the valveless piezoelectric pump with fractal-like Y-shape branching tubes.

Key words: pump;piezoelectric;fractal;flow resistance;Y-shape