Valveless Piezoelectric Pump Research Articles

Research on double-outlet valveless piezoelectric pump with fluid guiding body

In order to address the performance limitations of valveless piezoelectric pumps caused by backflow, a double-outlet valveless piezoelectric pump with a fluid guiding body to weaken liquid backflow energy has been designed. The pump chamber introduces a streamlined fluid guiding body incorporated with a double-outlet structure. When the piezoelectric pump absorbs water, the liquid from the outlet violently collides at the tail end of the fluid guiding body. The liquid then flows through the two ports and collides at the chamber, thereby attenuating the backflow liquid energy. The mechanism alleviates the problem of backflow in valveless piezoelectric pumps. This work examines the relationship between the main structural parameters of double-outlet valveless piezoelectric pumps with a fluid guiding body and the resulting energy loss of the backflow liquid. The effectiveness of the dual-outlet structure to suppress backflow of valveless piezoelectric pumps is analyzed using a finite element method, and the optimal pipe distance and tail distance parameters of the piezoelectric pump are predicted through multiple sets of simulations. Finally, a series of prototypes within the parameters of this study were produced, and experiments were performed. The test results show that the energy loss of the backflow liquid affects the output performance of the piezoelectric pump. In the parameter range investigated here, increasing the energy loss of the backflow liquid improves the performance of the valveless piezoelectric pump. The piezoelectric pump was designed to have a flow rate of 167.8 mL/min with a Piezoelectric actuator diameter of 35 mm at an applied voltage of 210 V at a frequency of 49 Hz.

Development of a valveless piezoelectric pump with vortex diodes

The cut-off capacity of the fluid diode determines the output performance of the valveless piezoelectric pump with flow resistance difference tubes. In this study, a valveless piezoelectric pump with vortex diodes is proposed, which utilizes the vortex diodes as internal valves with no moving parts. The internal flow field is calculated for the vortex diode with different chamber diameter ratios. The largest impedance ratio of the structural parameters of the vortex diode is obtained from the calculation results. Then, different prototypes of the piezoelectric pumps with a diffuser/nozzle, Tesla tubes and vortex diodes are manufactured. The experimental results demonstrate that the output performance of the valveless piezoelectric pump with vortex diodes is better than those of the other pumps: the maximum flow rate of the valveless piezoelectric pump with vortex diodes reaches 9.86 g min−1 at a driving voltage of 200 V with a driving frequency of 49 Hz, and the maximum output pressure of the piezoelectric pump reaches 340 Pa. In addition, the valveless piezoelectric pump with vortex diodes achieves a good carrying capacity, which is suitable for transmission of high-viscosity liquid. Flow field analysis demonstrates that strong vortex motion and strong shear forces exist near the center of the vortex chamber, which provide the basis function for fluid mixing and fluid separation.

Simulation of raindrop-shaped flow tube valveless piezoelectric pump

In order to promote the application of raindrop-shaped flow tube valveless piezoelectric pump (RSFTV PZT pump), basing on the existing research, the RSFTV PZT pump was simulated by computer. Firstly, the existence of the flow resistance of the flow tube was proved by simulation of FLUENT. Then, the dynamic mesh analysis of the pump was carried out to simulate the pumping flow rate at different driving frequencies. Lastly, the simulated results were compared with the experimental results, which shows that the flow rate tendency and value obtained by simulation are basically consistent with that by experiment. The simulation of the RSFTV PZT pump would be helpful to further accelerate related researches and promote the application of RSFTV PZT pump in MEMS and other fields.

Design and Experimental Verification of a PZT Pump with Streamlined Flow Tubes

In this paper, a streamlined flow tube valveless piezoelectric pump (SLFT PZT pump) is proposed to modify the single flow trend and improve the fluid flow stability. Firstly, the structural and working principle of the streamlined flow tube, which accounts for changing the flow trend and improving the flow stability, were analyzed. The flow resistance and flow rate equations were established. Secondly, the pressure and velocity fields of the tube were simulated. These simulated results were consistent with the theoretical results. Thirdly, the flow resistance of the flow tube was tested with pressure differences of 1000 Pa, 1200 Pa, 1400 Pa and 1600 Pa respectively. The trend of the result curves was consistent with the simulated results. The amplitude-frequency relationship and the flow-rate-frequency relationship were also tested, both result curves highly corelate. The maximum amplitude was 0.228 mm (10 Hz, 120 V), and the maximum flow rate was 17.01 mL/min (10 Hz, 100 V). Finally, the theoretical flow rate of the SLFT PZT pump was calculated at 100 V and 120 V. These results roughly fitted with the experimental results. The streamlined flow tube could change the internal flow trend that remarkably improved the flow stability. Therefore, it promoted the application of the valveless PZT pump in living cells, biomedical and polymer delivery.

Performance analysis of valveless piezoelectric pump with dome composite structures

Valveless piezoelectric pumps are used in the field of drug delivery. However, the output performances are limited by severe reflux. This article is aimed at reducing the reflux and improving the output performances. We use different pressure loss coefficients in the forward and reverse directions and design dome composite structures within the chamber of the valveless pump. The structures and working principles are described. Then, we use the fluid simulation software CFX to simulate the flow state inside the chamber under different parameters such as the dome length, 2 mm, 4 mm, 6 mm, and 8 mm; the trapezoidal one-sided angle, 1°, 3°, 5°, 7°, and 9°; and the rounded corner, from 0 to 6 mm. Finally, we also make the prototypes and test the output performances. The results show that the output flow rate can reach a maximum of 220.6 ml/min; the measured variance is 80.7 in the three experiment tests for the optimal flow rate at the dome length of 8 mm, angle of 5°, and rounded corner of 6 mm under the driving voltage of 190 V at a frequency of 45 Hz; the highest output pressure is 670.0 Pa under the voltage of 190 V at a frequency of 130 Hz. Moreover, the precision is 5.85% of the highest tested pressure compared to the simulated pressure. The output flow rate has a great improvement, and the effectiveness of the structures is proved.

A Novel PZT Pump with Built-in Compliant Structures.

Different to the traditionally defined valved piezoelectric (PZT) pump and valveless PZT pump, two groups of PZT pumps with built-in compliant structures—with distances between the free ends of 0.2 mm (Group A) and 0 mm (Group B)—were designed, fabricated, and experimentally tested. This type of pump mainly contains a chamber 12 mm in diameter and 1.1 mm in height, a PZT vibrator, and two pairs of compliant structures arranged on the flowing channel. The flow-resistance differences between these two groups of PZT pumps were theoretically and experimentally verified. The relationships between the amplitude, applied voltage and frequency of the PZT vibrators were obtained experimentally, with results illustrating that the amplitude linearly and positively correlates with the voltage, while nonlinearly and negatively correlating to the frequency. The flow rate performance of these two groups was experimentally tested from 110–160 Vpp and 10–130 Hz. Results showed that the flow rate positively correlates to the voltage, and the optimum flow rate frequency centers around 90 Hz for Group A and 80 Hz for Group B, respectively. The flow rate performances of Group B were further measured from 60–100 Hz and 170–210 Vpp, and obtained optimal flow rates of 3.6 mL/min at 210 Vpp and 80 Hz when ignoring the siphon-caused backward flow rate. As the compliant structures are not prominently limited by the channel’s size, and the pump can be minimized by Micro-electromechanical Systems (MEMS) processing methods, it is a suitable candidate for microfluidic applications like closed-loop cooling systems and drug delivery systems.

Design and Experimental Verification on Characteristics of Valve-Less Piezoelectric Pump Effected by Valve Hole Spacing

Valve-less piezoelectric pumps possess the advantages of simple structure and absence of electromagnetic interference, which has accordingly drawn widespread attention. In this paper, in order to improve the performance of valve-less piezoelectric pumps, various kinds of the prototypes had been designed and fabricated to discover the relationship between the performance and the structural parameters of valve hole spacing. The prototype is comprised of a piezoelectric actuator and a pump chamber through a conical tube that connects the pump chamber with the buffer chamber. First, the flow characteristics of the valve-less pump were performed by using COMSOL Multiphysics. According to the simulation result, the decline of flow velocity around the valve holes on the side far from the center of the pump chamber may be the reasons for the performance degradation. Second, the effect of valve hole spacing on the prototype was investigated with respect to several parameters, such as the chamber height and cone angle. The experimental results indicated that the valve-less piezoelectric pump output flowrate can be improved by reducing spacing valve hole spacing. A maximum flowrate of 8.43mL/min was achieved at valve hole spacing of 3 mm, which is 13.6% and 47.1% higher than that at 15 mm and 25 mm, respectively. We finally verify the feasibility of improving the capacity of valve-less piezoelectric pumps by reducing valve hole spacing.

Equivalent Circuit Modeling for a Valveless Piezoelectric Pump

Various kinds of the models had been proposed to explain the relationship between the performance and the structural parameters of valveless piezoelectric pumps, so as to evaluate the functional performance such devices. Among the models, the equivalent circuit model, which converts the multi-field problem of a valveless piezoelectric pump system into a simple circuit problem, is the most simple and clear one. Therefore, the proposed structure and working principle of the valveless piezoelectric pump with multistage Y-shape treelike bifurcate tubes are analyzed; then, the equivalent circuit model of the valveless piezoelectric pump is established based on the working principles of this pump and liquid-electric analogy theory. Finally, an experimental study of the pump is carried out, with a comparative analysis of the experimental results and the simulation results of the generated equivalent circuit. The experimental results show that with a driving voltage of 100 V and frequency of 6 Hz, the maximum flow rate of the valveless piezoelectric pump is 1.16 mL/min. Meanwhile, the output current of equivalent circuit also reaches its peak at the frequency of 6 Hz, therefore, indicating a good predictive ability of this model in calculating the maximum output flow rate and best working frequency of valveless piezoelectric pumps.

Experimental Verification of the Pumping Effect Caused by the Micro-Tapered Hole in a Piezoelectric Atomizer.

In this study, we examined the use of a dynamic micro-tapered hole as a micro-scale tapered flow tube valveless piezoelectric pump. Firstly, we obtained photographs of a micro-tapered hole by using an environmental scanning electron microscope (ESEM). Then, we explained the pump effect of the micro-tapered hole, and derived the atomization rate equation. Furthermore, we reported an atomization rate measurement experiment that eliminated the atomization caused by a pressure increase, and demonstrated that a change in the volume of a micro-tapered hole could produce atomization. The experimental results indicate that, under the same voltage, the forward atomization rate is much higher than the reverse atomization rate and that the atomization rate increases with the micro-tapered hole volume. The experimental results show that the atomization of the micro-tapered aperture atomizer is caused by its pumping effect. Moreover, the flow resistance and volume of the micro-tapered hole can affect the atomization rate.

Analysis of flow resistance property for valve-less piezoelectric pump with hemisphere-segment bluff-body

Abstract: Based on the principle that the flow resistances on spherical surface and round surface of hemisphere-segment in pump chamber are unequal, a novel valve-less piezoelectric pump with hemisphere-segment bluff-body (HSBB) is presented. The pumping performance depends directly on the flow resistances and their change law on hemisphere-segment surfaces. Therefore, it is necessary to study the flow resistance property of HSBB. This study finds that the forward and reverse flow resistances on HSBB cannot be solved simultaneously by traditional theoretical and experimental hydrodynamics equivalent method for flow resistance around non-sphere. Based on the geometric features of hemisphere-segment the method of Equivalent Flow Resistance Diameter was proposed, and the forward and reverse equivalent spheres respectively corresponding to the spherical and round surface of hemisphere-segment were separated and the sphere diameters were calculated. Flow resistance measuring device was designed, and the flow resistance coefficient of hemisphere-segment was obtained by testing and calculating. The theoretical formulas of forward and reverse flow resistance on hemisphere-segment were established. And through experiments it is verified that the method proposed in this paper is feasible and can be applied to analyze and calculate flow resistance and pumping flow rate in pump. Keywords: valve-less piezoelectric pump, equivalent flow resistance, flow around hemisphere-segment, flow resistance coefficient DOI: 10.33440/j.ijpaa.20210401.149 Citation: Li S D, Zhao W, Ji J, Hu C Q, Hu X Q. Analysis of flow resistance property for valve-less piezoelectric pump with hemisphere-segment bluff-body. Int J Precis Agric Aviat, 2021; 4(1): 14–21.

Optimal Design and Simulation of a Microsuction Cup Integrated with a Valveless Piezoelectric Pump for Robotics

The traditional suction mechanism with an air pump in robotics is difficult to miniaturize. Integrating a piezoelectric pump into a suction cup is an effective method to achieve miniaturization. In this paper, a novel suction cup with a piezoelectric micropump is designed. The micropump is valveless and the suction cup is designed with a laminated structure in order to facilitate miniaturizing and manufacturing. A systematic optimization design method of the suction cup is introduced which addresses the static and dynamic driving characteristics of the piezoelectric actuator and the rectifying efficiency of diffuser/nozzle’s optimization. The design is verified via simulation using an improved equivalent electric network model. Static lumped parameters in this model are calculated by the finite element method instead of the traditional analytic method, and the diffuser/nozzle’s flow resistance is computed by integrating and introducing rectifying efficiency coefficient. Simulation results indicate that the suction cup can generate a stable negative pressure, and the equivalent electric network model can improve the simulation efficiency and accuracy. The maximum steady‐state negative pressure of the suction cup can also be effectively improved after optimization.

Advances in Valveless Piezoelectric Pump with Cone-shaped Tubes

This paper reviews the development of valveless piezoelectric pump with cone-shaped tube chronologically, which have widely potential application in biomedicine and micro-electro-mechanical systems because of its novel principles and deduces the research direction in the future. Firstly, the history of valveless piezoelectric pumps with cone-shaped tubes is reviewed and these pumps are classified into the following types: single pump with solid structure or plane structure, and combined pump with parallel structure or series structure. Furthermore, the function of each type of cone-shaped tubes and pump structures are analyzed, and new directions of potential expansion of valveless piezoelectric pumps with cone-shaped tubes are summarized and deduced. The historical argument, which is provided by the literatures, that for a valveless piezoelectric pump with cone-shaped tubes, cone angle determines the flow resistance and the flow resistance determines the flow direction. The argument is discussed in the reviewed pumps one by one, and proved to be convincing. Finally, it is deduced that bionics is pivotal in the development of valveless piezoelectric pump with cone-shaped tubes from the perspective of evolution of biological structure. This paper summarizes the current valveless piezoelectric pumps with cone-shaped tubes and points out the future development, which may provide guidance for the research of piezoelectric actuators.

Multi-Field Analysis and Experimental Verification on Piezoelectric Valve-Less Pumps Actuated by Centrifugal Force

A piezoelectric centrifugal pump was developed previously to overcome the low frequency responses of piezoelectric pumps with check valves and liquid reflux of conventional valveless piezoelectric pumps. However, the electro-mechanical-fluidic analysis on this pump has not been done. Therefore, multi-field analysis and experimental verification on piezoelectrically actuated centrifugal valveless pumps are conducted for liquid transport applications. The valveless pump consists of two piezoelectric sheets and a metal tube with piezoelectric elements pushing the metal tube to swing at the first bending resonant frequency. The centrifugal force generated by the swinging motion will force the liquid out of the metal tube. The governing equations for the solid and fluid domains are established, and the coupling relations of the mechanical, electrical and fluid fields are described. The bending resonant frequency and bending mode in solid domain are discussed, and the liquid flow rate, velocity profile, and gauge pressure are investigated in fluid domain. The working frequency and flow rate concerning different components sizes are analyzed and verified through experiments to guide the pump design. A fabricated prototype with an outer diameter of 2.2 mm and a length of 80 mm produced the largest flow rate of 13.8 mL/min at backpressure of 0.8 kPa with driving voltage of 80 Vpp. By solving the electro-mechanical-fluidic coupling problem, the model developed can provide theoretical guidance on the optimization of centrifugal valveless pump characters.

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 mL/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.

三棱柱阻流体无阀压电泵的设计与试验

以三棱柱阻流体为无移动部件阀,结合3D打印技术的快速一体成型特点,设计并制作了以压电振子为动力源的三棱柱阻流体无阀压电泵.分析了该无阀压电泵的工作原理、理论流量和振子振动特性,推导出了它的的流量表达式.利用有限元法对三棱柱阻流体的流阻特性进行了仿真模拟,由其内部压强分布及进出口流速情况,定性分析了三棱柱阻流体的正反向流阻大小.最后,使用3D打印机制作了该无阀泵的试验样机,并进行了流阻和流量测量试验.试验结果表明:三棱柱阻流体具有正反向绕流流阻不等的特性,当驱动电压为550 V,驱动频率为8 Hz时,该压电泵的输出流量达到最大,为29.8 mL/min.结果证明了该三棱柱阻流体无阀压电泵具有良好的输送流体的能力.

Analysis of Flow Field and Pumping Performance for a Valveless Piezoelectric Pump with a Hemisphere-segment Group

The pumping and mixing performance of a valveless piezoelectric pump were proposed and studied. A hemisphere-segment group that was fixed in the pump played the role of a valve. Based on the theoretical analysis of the pumping performance, the changes of the fluid velocity field, pressure difference, the coefficient of resistance and flow rate were simulated with FLUENT. Simulation results revealed the relationships among the pressure field, flow rates, row and column numbers, and row and column intervals of the hemisphere-segment group. The simulation results indicated that increasing row and column numbers, increasing row intervals, and decreasing column intervals could all increase the flow resistance difference in pump flow field and thus increased the flow rate. It was also found that the pumping effect was significantly improved by increasing row number than increasing column number; the increasing of row and column intervals could increase the size and strength of the vortex, and then improve the mixing and stirring performance of this pump. Finally, simulation results were tested and verified through pump flow-rate experiments.

非零迎流角半球缺群无阀泵流场及流量特性

非零迎流角半球缺群无阀泵流场及流量特性

Simulation analysis and experimental verification of spiral-tube-type valveless piezoelectric pump with gyroscopic effect

The current research of the valveless piezoelectric pump focuses on increasing the flow rate and pressure differential. Compared with the valve piezoelectric pump, the valveless one has excellent performances in simple structure, low cost, and easy miniaturization. So, their important development trend is the mitigation of their weakness, and the multi-function integration. The flow in a spiral tube element is sensitive to the element attitude caused by the Coriolis force, and that a valveless piezoelectric pump is designed by applying this phenomenon. The pump has gyroscopic effect, and has both the actuator function of fluid transfer and the sensor function, which can obtain the angular velocity when its attitude changes. First, the present paper analyzes the flow characteristics in the tube, obtains the calculation formula for the pump flow, and identifies the relationship between pump attitude and flow, which clarifies the impact of flow and driving voltage, frequency, spiral line type and element attitude, and verifies the gyroscopic effect of the pump. Then, the finite element simulation is used to verify the theory. Finally, a pump is fabricated for experimental testing of the relationship between pump attitude and pressure differential. Experimental results show that when Archimedes spiral θ=4π is selected for the tube design, and the rotation speed of the plate is 70 r/min, the pressure differential is 88.2 Pa, which is 1.5 times that of 0 r/min rotation speed. The spiral-tube-type valveless piezoelectric pump proposed can turn the element attitude into a form of pressure output, which is important for the multi-function integration of the valveless piezoelectric pump and for the development of civil gyroscope in the future.

Theoretical analysis and experimental verification on valve-less piezoelectric pump with hemisphere-segment bluff-body

Existing researches on no-moving part valves in valve-less piezoelectric pumps mainly concentrate on pipeline valves and chamber bottom valves, which leads to the complex structure and manufacturing process of pump channel and chamber bottom. Furthermore, position fixed valves with respect to the inlet and outlet also makes the adjustability and controllability of flow rate worse. In order to overcome these shortcomings, this paper puts forward a novel implantable structure of valve-less piezoelectric pump with hemisphere-segments in the pump chamber. Based on the theory of flow around bluff-body, the flow resistance on the spherical and round surface of hemisphere-segment is different when fluid flows through, and the macroscopic flow resistance differences thus formed are also different. A novel valve-less piezoelectric pump with hemisphere-segment bluff-body (HSBB) is presented and designed. HSBB is the no-moving part valve. By the method of volume and momentum comparison, the stress on the bluff-body in the pump chamber is analyzed. The essential reason of unidirectional fluid pumping is expounded, and the flow rate formula is obtained. To verify the theory, a prototype is produced. By using the prototype, experimental research on the relationship between flow rate, pressure difference, voltage, and frequency has been carried out, which proves the correctness of the above theory. This prototype has six hemisphere-segments in the chamber filled with water, and the effective diameter of the piezoelectric bimorph is 30mm. The experiment result shows that the flow rate can reach 0.50 mL/s at the frequency of 6 Hz and the voltage of 110 V. Besides, the pressure difference can reach 26.2 mm H2O at the frequency of 6 Hz and the voltage of 160 V. This research proposes a valve-less piezoelectric pump with hemisphere-segment bluff-body, and its validity and feasibility is verified through theoretical analysis and experiment.

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.