非对称坡面腔底无阀压电泵流场分析

无阀压电泵需要外接用于产生单向流动流管,阻碍了压电泵的微小型化,针对这一缺点提出了非对称坡面腔底无阀压电泵,该压电泵将用于产生单向流动的部件——非对称坡面集成于泵腔的底部。对非对称坡面腔底无阀压电泵进行了计算机建模,基于商用Fluent12软件运用自定义函数(user defined functions,简称UDF)对压电振子运动形式进行了模拟;采用RNGκ-ε湍流模型对瞬态N-S方程进行了求解,分析了泵腔内流场;得出了从20°到70°不同坡面角度下的平均流量,在坡面角为20°时,可以得到最大平均流量为0.864 ml/min,并通过流量测量试验测得该泵的最大流量达到了8.6 ml/min。从仿真和试验的角度验证了该泵的可行性。     

非对称坡面腔底无阀压电泵

提出了一种新型的非对称坡面腔底无阀压电泵,这种泵巧妙地利用了泵腔内部的空间,将泵腔底部沿吸入口和排出口方向设计成非对称坡面形状,非对称坡面腔底与压电振子之间形成非对称交替排列的一组锥形流道.当泵工作时,使流体产生单向流动,从而可以不再需要传统的锥形流管;建立了这种泵关于平均值的流阻系数与泵流量关系的力学模型,并利用该模型分析了泵的工作原理;最后制作了非对称坡面腔底无阀压电泵,利用试验证明了上述理论的正确性.试验用泵采用的工作电压为220 V,工作频率为50 Hz,压电振子有效直径为30 mm,当非对称坡面的倾角差为70°,工作介质为水时,泵产生了4.67 mm水柱的压差.     

非对称分叉流管无阀压电泵的设计及试验

具有微混合功能的多级Y型流管无阀压电泵存在着输出流量与振子带载能力不平衡的问题。为此，提出了一种非对称分叉流管无阀压电泵。首先，理论分析了该无阀压电泵输出流量与流管流阻间的关系；其次，利用有限元软件数值计算了多级Y型流管的流阻特性；最后，采用光固化快速成型技术加工了样机，并进行了泵特性试验和振子振动测试。试验结果表明：在峰峰值200 V正弦波交流电驱动下，该压电泵的流量、扬程和压电振子的振幅都随驱动频率增加呈现先增大后减小的趋势；当驱动频率为31 Hz时，最大流量为4 g/min；驱动频率为38 Hz时，最大扬程为40.5 mmH2O。在试验施加电压范围内，该泵的输出性能与驱动电压呈正相关性。本研究验证了非对称流道树型无阀压电泵的可行性，为非对称无阀压电泵在微流道滴灌和微混合等领域的应用提供了参考。     

多级“Y”型流管无阀压电泵的原理与试验验证(实验视频)

针对目前微流体混合器多需要外接动力源,且多数微混合器只能进行液体混合而不能输送液体的问题,提出将无阀压电泵引入微混合器领域,并研制了一种集混合与输送于一体的多级“Y”型流管无阀压电泵。首先,提出了多级“Y”型流管,进而设计了多级“Y”型流管无阀压电泵,并分析其工作原理;然后,对该无阀压电泵的流管流阻特性及泵流量进行理论分析;同时,利用有限元软件对多级“Y”型流管无阀压电泵进行了流场模拟,结果表明该压电泵具有单向传输作用。最后,制作了多级“Y”型流管无阀压电泵样机,并进行了泵流量与背压试验。试验结果显示：驱动电压峰峰值为100 V,频率为16 Hz时,流量达到最大,为16.2 ml/min;驱动电压峰峰值为100 V,频率为14 Hz时,输出背压最大,约为64 mm水柱。得到的试验数据证明了多级“Y”型流管无阀压电泵的有效性。(实验视频)     

变截面“Y”型流管无阀压电泵原理及试验

根据三通全扩散/收缩流管的结构形式,设计了一种无阀压电泵——变截面“Y”型流管无阀压电泵。首先,分析了变截面 “Y”型流管无阀压电泵的工作原理;然后,对变截面“Y”型流管流阻和泵流量进行理论分析,对变截面“Y”型流管进行模拟,得到流管正反向压强损失系数;最后,制作变截面“Y”型流管无阀压电泵样机,并进行流量试验。试验表明：当驱动电压为100 V、驱动频率为12.4 Hz时,流量达到最大,为25.7 ml/min;使用定频12.4 Hz改变电压,当电压为200 V时,最大流量达到41.6 ml/min。该组试验证明了变截面“Y”型流管无阀压电泵的有效性。     

"Y"形流管无阀压电泵模拟与试验

对"Y"形流管无阀压电泵内部流场及泵流量特性进行了模拟及试验研究.采用CFX软件对"Y"形流管无阀压电泵泵腔内的流场特性进行了模拟分析.结果表明:"Y"形流管无阀压电泵工作时泵腔内的压强变化很小,涡旋对流体传输活体细胞及长链大分子基本无影响.实际制作了"Y"形流管无阀压电泵,并通过改变"Y"形流管的几何尺寸,研究了压电泵进出口端压差的变化规律.试验结果表明,压差随支管夹角增大而减小,并且当两支管宽的和接近主管宽时,压差值达到最小,当支管夹角为5°,宽为1.2 mm时,压差达到最大725 Pa.     

“Y”形流管无阀压电泵模拟与试验研究

为了对“Y”形流管无阀压电泵的工作特性有更深入的了解,使其更好地满足输血、输液等工作的需要,对“Y”形流管无阀压电泵内部流场及泵流量特性进行了模拟及试验研究。采用CFX软件对“Y”形流管无阀压电泵泵腔内的流场特性进行了模拟分析。结果表明：“Y”形流管无阀压电泵工作时泵腔内的压强变化很小,涡旋对流体传输活体细胞及长链大分子基本无影响。实际制作了“Y”形流管无阀压电泵,并通过改变“Y”形流管的几何尺寸,研究了压电泵进出口端压差的变化规律。试验结果表明压差随支管夹角增大而减小,并且当两支管宽的和接近主管宽时,压差值达到最小,当支管夹角为5°,宽为1.2mm时,压差达到最大的74mm水柱。     

螺线形流管无阀压电泵的试验研究

流体在螺线形流管中流动时受到的哥氏力,能够增强流体的传质效果,实现输送流体的功能。研究表明进出流管一侧为斜线另一侧为螺旋线的单螺线形流管无阀泵具有泵功能,而进出流管形状为异向螺线时相较于单螺线形流管哪种泵输出性能更优,以及进出流管形状为同向螺线形时是否具有"泵"功能,或者其输出是否低于异向螺线形流管无阀泵,却没有相关研究。为了更好地发挥螺线形流管在无阀压电泵中的优势,拓展该种类无阀泵的应用场合,需要进一步探讨螺线形流管的布局方式对泵输出性能的影响。分析流体在螺线形流管内部的流动情况,推导顺、逆时针流动时的速度差公式,认为螺线形流管无阀泵流量是由进、出水流管的流阻差造成的。利用3D打印技术,设计制作同向螺线、异向螺线以及单螺线形流管三种不同流管布局的无阀压电泵,测量不同频率下三种泵的流量。发现相同电压下,单螺线形流管无阀泵的流量最大,且其最佳工作频率也最大;同向螺线形流管无阀泵也有泵输出,但是输出量很小;当螺线形流管无阀泵的驱动功率较小,其驱动力不足以抵抗流管沿程的流阻损失时,反而体现不出其螺线形流管的优势。     

细胞或高分子输送用"Y"形流管无阀压电泵的工作原理及流量特性

在泵腔上安装两支互为倒置的具有一定夹角的三通流管,组成泵腔的流入、排出口,并与压电振子、泵体及其他部件共同构成了"Y"形流管无阀压电泵.该泵无自身化学污染源及电磁污染源,也没有阀的开启过程;同时,具有极大的可微小化和集成化的结构能力;而且,在流管内产生的漩涡相对较小,有利于输送活体细胞及长链高分子.提出新型"Y"形流管无阀压电泵的结构.基于有限体积法,分别模拟锥形流管与"Y"形流管中的压力分布与速度矢量分布,证明"Y"形流管中的漩涡远小于圆锥流管中的漩涡,速度、压力的变化也较圆锥流管低.通过具体分析压电振子的振动,建立泵容积变化方程;同时建立泵流量与压电振子频率之间的关系式.最后,通过对所研究的"Y"形流管无阀压电泵进行流量试验后证明"Y"形流管无阀压电泵具有泵特性,进而证明了上述理论模型的正确性.     

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550V,驱动频率为8 Hz时,该压电泵的输出流量达到最大,为29.8mL/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。     

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.     

Theory and experimental verification on valveless piezoelectric pump with multistage Y-shape treelike bifurcate tubes

Among most traditional piezo water cooling systems, piezoelectric valve pumps are adopted as their driving sources. The valves in these pumps induce problems of shock and vibration and also make their structure complicated, which is uneasy to minimize and reduce their reliability and applicability of the whole system. In order to avoid these problems caused by valve structure, a novel valveless piezoelectric pump is developed, which integrates both functions of transforming and cooling. The pump’s Y-shape tree-like construction not only increases the efficiency of cooling but also the system reliability and applicability. Firstly, a multistage Y-shape treelike bifurcate tube is proposed, then a valveless piezoelectric pump with multistage Y-shape treelike bifurcate tubes is designed and its working principle is analyzed. Then, the theoretical analysis of flow resistance characteristics and the flow rate of the valveless piezoelectric pump are performed. Meanwhile, commercial software CFX is employed to perform the numerical simulation for the pump. Finally, this valveless piezoelectric pump is fabricated, the relationship between the flow rates and driving frequency, as well as the relationship between the back pressure and the driving frequency are experimentally investigated. The experimental results show that the maximum flow rate is 35.6 mL/min under 100 V peak-to-peak voltage (10.3 Hz) power supply, and the maximum back pressure is 55 mm H2O under 100 V (9 Hz) power supply, which validates the feasibility of the valveless piezoelectric pump with multistage Y-shape treelike bifurcate tubes. The proposed research provides certain references for the design of valveless piezoelectric pump and improves the reliability of piezo water cooling systems.     

半柔性阀压电泵理论与实验

根据静脉瓣结构形式,设计了一种半柔性阀压电泵。首先,介绍了半柔性阀压电泵的结构及工作原理;其次,对阀体进行了理论分析;最后,加工了实验样机,对样机进行性能测试实验。实验结果表明:在驱动电压为220V、频率为7Hz时,半柔性阀压电泵的进出口压差可达到199mm;在驱动电压为220V、频率为11Hz时,半柔性阀压电泵的实验流量为44.5ml/min。随着驱动电压的升高,工作频率与流量出现单峰与双峰的现象。该研究证明了半柔性阀压电泵具有泵的功能并可以实现有阀和无阀状态,验证了其有效性和理论分析的正确性。     

基于MEMS的压电微泵建模与优化

以压电驱动的无阀微泵为研究对象,根据扩张管/收缩管的压力损失系数和连续方程,建立了无阀微泵的理论模型。利用有限元分析软件,建立了无阀微泵有限元模型,进行了耦合场仿真分析。模拟并分析了不同边界条件下驱动电压、电压频率、泵膜厚度、压电薄膜厚度和压电材料对无阀微泵输出特性的影响。仿真结果显示,无阀微泵具有很好的整流特性,并且驱动电压越大,输出特性越好。在局部固定边界条件下,当压电薄膜上施加电场强度为500 V/mm的驱动电压时,存在最优的压电薄膜厚度,使得微泵的输出流量最大。研究结果为无阀微泵的优化设计提供了依据。     

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 of80 mm produced the largest flow rate of 13.8 m L/min at backpressure of 0.8 k Pa with driving voltage of 80 Vpp. Bysolving 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.     

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.