Analysis of the Flow Rate Characteristics of Valveless Piezoelectric Pump with Fractal-like Y-shape Branching Tubes

Microchannel heat sink with high heat transfer coefficients has been extensively investigated due to its wide application prospective in electronic cooling. However, this cooling system requires a separate pump to drive the fluid transfer, which is uneasy to minimize and reduces their reliability and applicability of the whole system. In order to avoid these problems, valveless piezoelectric pump with fractal-like Y-shape branching tubes is proposed. Fractal-like Y-shape branching tube used in microchannel heat sinks is exploited as no-moving-part valve of the valveless piezoelectric pump. In order to obtain flow characteristics of the pump, the relationship between tube structure and flow rate of the pump is studied. Specifically, the flow resistances of fractal-like Y-shape branching tubes and flow rate of the pump are analyzed by using fractal theory. Then, finite element software is employed to simulate the flow field of the tube, and the relationships between pressure drop and flow rate along merging and dividing flows are obtained. Finally, valveless piezoelectric pumps with fractal-like Y-shape branching tubes with different fractal dimensions of diameter distribution are fabricated, and flow rate experiment is conducted. The experimental results show that the flow rate of the pump increases with the rise of fractal dimension of the tube diameter. When fractal dimension is 3, the maximum flow rate of the valveless pump is 29.16 mL/min under 100 V peak to peak （13 Hz） power supply, which reveals the relationship between flow rate and fractal dimensions of tube diameter distribution. This paper investigates the flow characteristics of valveless piezoelectric pump with fractal-like Y-shape branching tubes, which provides certain references for valveless piezoelectric pump with fractal-like Y-shape branching tubes in application on electronic chip cooling.

3D FEM Analyses on Flow Field Characteristics of the Valveless Piezoelectric Pump

Due to the special transportation and heat transfer characteristics,the fractal-like Y-shape branching tube is used in valveless piezoelectric pumps as a no-moving-part valve.However,there have been little analyses on the flow resistance of the valveless piezoelectric pump,which is critical to the performance of the valveless piezoelectric pump with fractal-like Y-shape branching tubes.Flow field of the piezoelectric pump is analyzed by the finite element method,and the pattern of the velocity streamlines is revealed,which can well explain the difference of total flow resistances of the piezoelectric pump.Besides,simplified numerical method is employed to calculate the export flow rate of piezoelectric pump,and the flow field of the piezoelectric pump is presented.The FEM computation shows that the maximum flow rate is 16.4 m L/min.Compared with experimental result,the difference between them is just 55.5%,which verifies the FEM method.The reasons of the difference between dividing and merging flow resistance of the valveless piezoelectric pump with fractal-like Y-shape branching tubes are also investigated in this method.The proposed research provides the instruction to design of novel piezoelectric pump and a rapid method to analyse the pump flow rate.