Xiaoqi Hu

Principle and experimental verification of caudal-fin-type piezoelectric-stack pump with variable-cross-section oscillating vibrator

In the traditional flow-resistance-differential (FRD) type valve-less piezoelectric pump, the generated outflow and pressure are discontinuous because of the inherent periodicity and fluctuation of the pump. To overcome these drawbacks, utilizing the bending vibration of piezoelectric bimorph to drive fluid was conducted. However, our investigation on the current status of this piezoelectric bimorph pump shows that larger driving force and vibration amplitude are required for fluid pumping; the pumping can be realized through the centrifugal force; and the mechanism of fluid pumping is no longer further studied. Based on these cases, the paper designed a piezoelectric-stack pump with variable-cross-section oscillating (VCSO) vibrator by imitating the swing of the caudal-fin of tuna, and the pump is neither the rotating type nor the volumetric type according to the taxonomy. The interaction between the oscillating vibrator and the fluid parcel is firstly analyzed from the viewpoint of momentum conservation, and the analytical expression of pump flow rate is obtained. Then the modal and harmonic response analyses on the vibrator immerged in water are carried out. From the analyses the first two orders resonance frequencies are 832 Hz and 1 939 Hz, respectively, and the peak value of the tip amplitude is 0.6 mm. Laser Doppler vibrometer is used to measure both the frequency and vibration amplitude, and the determined first two orders resonance frequencies are 617 Hz and 1 356 Hz, respectively. The measured tip amplitude reaches to the peak value of 0.3 mm. At last, experimental measurement for the flow rates with different driving frequencies is conducted. The results show that the flow rate can reach 560 mL/min at 1 370 Hz when the pump runs under the backpressure of 30 mm water column. And the flow rate is as much as 560% of that of experiment results carried out by researchers from Brazil. The proposed pump innovates in both theory and taxonomy; in addition, the pump overcomes the drawbacks such as large flow fluctuation and low flow rate in the traditional FRD type pumps, which will help to broaden the application of the valve-less piezoelectric pump.

Dynamics analysis and flow rate experiments on the fish-tailing type of valveless piezoelectric pump with rectangular vibrator

In recent years, the research and development of piezoelectric pumps have become an increasingly popular topic. Minimization, structure simplification and stronger output became the focus of piezoelectric pumps research due to its possible application in MEMS technology. The valveless fishtailing piezoelectric pump with rectangular vibrator, neither a volumetric nor a rotating pump, was invented according to the bionics of fish swimming. Assume fish were in still while its tail was swinging, fluid would flow toward the end of the tail, achieving the function as a valveless pump. This type of pump creates a new branch of the piezoelectric pump research, and it is proposed for the first time in this paper. Firstly, the dynamics analysis for the deformation of the vibrator was provided. Then the mathematical results of the flow rates for the pump are also resolved. Finally, the experiments to test the flow rates with different driving frequencies were carried out and the results showed that in the first banding vibration mode the piezoelectric vibrator reach its maximum flow rate of 2.0ml/min at the driving frequency of 49 Hz. On the other hand, in the second banding mode, the maximum flow rate achieved 6.4ml/min at the frequency of 460 Hz. The experimental results verified the theoretical explanation and the mathematical analysis.

Theoretical and experimental research of caudal-fin-type piezoelectric-stack pump with variable-cross-section oscillating vibrato

In this paper, a piezoelectric-stack pump with variable-cross-section oscillating (VCSO) vibrator is proposed, which imitates the swing of the caudal-fin of tuna, and the pump is neither the rotating type nor the volumetric type according to the taxonomy. The interaction between the oscillating vibrator and the fluid parcel is firstly analyzed from the viewpoint of momentum conservation, and the analytical expression of pump flow rate is obtained. At last, experimental measurement for the flow rates with different driving frequencies is conducted. The results show that the flow rate can reach 560 ml/min at 1370 Hz when the pump runs under the backpressure of 30 mm water column. And the flow rate is as much as 560% of that of experiment results carried out by Cícero R. De Limaa. The proposed pump innovates in both theory and taxonomy. In addition, the pump overcomes the drawbacks such as large flow fluctuation and low flow rate in the traditional FRD type pumps, which will help to broaden the applications of the valve-less piezoelectric pump.

Analysis on flow field of piezoelectric pump with unsymmetrical slopes element

Traditional valveless piezoelectric pumps are difficult to be minimized for its special tubes installed outside the chamber. Moreover, the effect of mixing different kinds of liquid is not good. In order to improve the configuration and performance of the pump, a novel valveless piezoelectric pump - valveless piezoelectric pump with unsymmetrical slopes elements (USE) is developed. It is designed aimed at intensing the vortex field in the chamber during pumping. The intense vortex field is helpful to stir and mix different liquids in th e chamber to produce solution, homogeneous emulsion or turbid liquid. Firstly, pumping principle of the proposed pump is analyzed. Then, numerical models are established, and simulation and numerical calculation on the flow fields in the chambers ar e carried out.Finally, experiments are implemented to verify the validity and reliability of numerical analysis.

A novel piezoelectric pump with E-shaped valve found from the subdivision experiment

Increasing the driving frequency of piezoelectric vibrator can resolve the bottleneck of low flow of the valve piezoelectric pump. However, the using of piezoelectric pump of traditional valve body all presents the hysteretic nature of valve; macroscopic performance is up-frequency to flow-sharply. This research is to settle the bottleneck mentioned above: firstly, through the sub-experiment on various parameters of plate valve of piezoelectric pump, the reasons for how valve body itself can influence “up-frequency to flow-sharply”, which causes the hysteretic nature of valve, were discovered; then, E-shaped valve and piezoelectric pump with E-shaped valve (PPEV) were invented with purpose; finally, the efficiency of PPEV has been proved helpful to reduce hysteretic nature in experiment. Under the same conditions, the driving frequency of novel PPEV can be over 10 times higher and the flow rate can be also several times larger than traditional pumps.

Research on a novel piezoelectric pump with unsymmetrical slopes element

This paper describes a novel valveless piezoelectric pump which utilizes the unsymmetrical slopes element (USE) inside the chamber to produce net flow. Firstly, pumping principle of the proposed pump is analyzed. The flow resistances take different values when liquid flows in opposite direction, owing to the asymmetry in structure of slopes element. As a result, net flow is produced. Secondly, numerical models are established, and the simulation on the flow fields in the chambers are carried out. Finally, experiments are implemented to verify the validity and reliability of numerical analysis. Pressure head reaches 16mm when slant angle of USE get the value of 20° and the data agree well with analysis result.