压电双晶片和单晶片驱动下泵的输出性能研究

为从理论上获得压电泵在薄片型压电双晶片和单晶片(统称压电振子)驱动时的输出流量关系,需要获得二者振动时产生的容积变化量。假设压电振子在周边固定约束条件下,应用弹性薄板的小挠度弯曲变形理论,推导了压电双晶片和单晶片振动时的容积变化方程,并根据方程对铜基板直径为35mm,压电陶瓷直径为29mm,基板和压电陶瓷厚度同时为0.2mm和0.3mm 2种规格的压电单晶片和双晶片进行了振动容积计算。计算结果显示,相同基板和陶瓷厚度的双晶片振动产生的容积变化量是单晶片的2.3倍。将上诉压电振子应用到单腔压电泵上进行输送气体流量测试,获得的实际输出流量比在1.5~2倍之间,理论计算结果与试验测试结果比较接近。理论推导结果为比较双晶片和单晶片驱动下压电泵的输出能力提供了可靠依据。     

不同容积比的双腔串联压电泵测试分析

为提高双腔串联压电泵的输出性能,对泵的进口腔与出口腔的容积比进行了优化设计。分别设计了容积比为1.9、1.5、1.3三种串联压电泵样机,并对样机进行了试验测试。试验结果显示,采用增加容积比的方式可以提高双腔串联压电泵的输出流量,但不能提高其输出压力;对每个不同腔体容积比的双腔串联压电泵在异步驱动和同步驱动下进行了输出性能测试,测试结果显示,当输送气体时,两种驱动方式均有很好的流量输出,且输出结果比较接近,但仅有异相驱动时才能输出液体。分析结果为提高双腔串联压电泵的输出性能提供了很好的依据。     

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     

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 H20 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.     

A magnetic MEMS actuator using a permanent magnet and magnetic fluid enclosed in a cavity sandwiched by polymer diaphragms

A magnetic microelectromechanical systems (MEMS) actuator using a small permanent neodymium-magnet surrounded by magnetic fluid (MF) was developed and characterized. The magnet is enclosed in a cavity sandwiched by two identical thin PET-sheet diaphragms and is able to move smoothly due to the MF. The diaphragms deflect when an external magnetic force is applied to the magnet. This structure was adopted to prevent the diaphragms from being stiffened by attaching or fabricating a magnetic layer on the diaphragm surface and to secure the necessary volume of magnetic material. The magnets are 2–4 mm in diameter and the cavity is 5 mm in diameter and 1 mm in depth. The diaphragms are 20 μm in thickness. Experiments showed the displacement amplitude generated at the diaphragm center was in the range of 10–50 μm for attractive and repulsive magnetic force when magnetic flux density of 4–30 mT was applied. The response was within about 1 s. The deflection profile of the diaphragms can also be varied by changing the magnet position.     

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.     

A new device for continuous ambulatory central venous pressure measurement

We have developed a device for continuous direct measurement of human central venous pressure (CVP) during space flight. Normal resting CVP is typically in the range of 5-10 mmHg; in zero gravity, the expected changes are +/- 5 mmHg or less. A 1-mm Hg change in CVP can represent a substantial intravascular fluid shift. The device is small, battery powered, and designed to run for at least 24 hr. Pressure is measured in a saline solution-filled catheter inserted into a central vein. The transducer is placed in the axilla at the level of the catheter tip to offset hydrostatic gradients. A pump and an electronic system mount on the leg. This assembly provides a slow, continuous infusion of heparinized saline solution to maintain the patency of the catheter. The electronic system generates a digital display in mm Hg, an analog output, and a visible and audible alarm for excessive pressure. An air-filled syringe allows for a two-point calibration (zero and a positive pressure generated by measured compression of a known gas volume). A two-failure tolerant system minimizes electric shock hazards. Two latex diaphragms separate the saline solution from the transducer surface, and the electronic system and pump chamber are in separate enclosures. A clear polycarbonate case allows bubbles to be seen. The unit has been tested for pump function, temperature stability, drift, and accuracy. We conclude that this approach provides a unit with sufficient stability, accuracy, and temperature insensitivity for measuring ambulatory CVP for up to 28 hr. The design may be suitable for ambulatory measurement of other intravascular and intracardiac pressures.     

微型压电泵中腔高对气泡滞留的影响规律

气泡滞留会严重地损害微型压电泵的输出性能,因此减少气泡滞留将有效地提高压电泵系统的稳定性和可靠性。泵腔作为气泡滞留的主要区域,同时是决定输出性能的重要元素,所以改变腔高将对气泡滞留产生重要的影响。本文从气泡压力降和输出压力两个方面建立数学模型,以此分析腔高对气泡滞留的影响规律,最后通过气泡滞留实验进行验证。实验结果表明,腔高为0.15mm时,压电泵具有优良的输出性能和排气泡能力,在进入120个0.02mL气泡后,压电泵仍具有稳定的输出压力(8.1kPa)和输出流量(4.2mL/min);腔高为0.05mm和0.20mm时,压电泵在进入一个气泡后即丧失了工作能力,排气泡能力差,而腔高为0mm和0.10mm时,压电泵分别进入47和70个气泡后丧失了工作能力。实验表明选取合理的腔高可以有效地减少气泡的滞留。     

磁力弹簧式压电共振型气泵的设计

利用压电振子的振动激励相连接的隔膜共振原理,提出了用磁力弹簧式压电共振型气泵来提高压电泵对气体的驱动能力.首先,分析磁力弹簧式共振泵的工作原理,建立了共振泵的动力学模型,计算得出了影响隔膜振幅的主要因素.接着,设计和制作了样机,使用阻抗分析仪和激光位移计分别测得系统的共振频率及压电振子的位移放大倍数.最后,设计了测量共振泵流量和输出压力的实验装置,得出了磁力弹簧轴向间距对输出流量和输出压力的影响.实验测试表明:当输入正弦电压为200 V,系统共振频率为134 Hz,磁力弹簧的轴向间距为9 mm时,压电振子的位移放大倍数约为4.3,其最佳输出流量为524 ml/min,最佳输出压力为9.2 kPa.结果显示,提出的磁力弹簧式压电共振型气泵提高了气体的输送能力.     

“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。     

分流组合模挤压过程数值模拟及模具应力分析

采用有限体积数值模拟方法研究分流组合模中焊合室的深度对铝型材挤压过程的影响,分别采用21mm、26mm和31mm三种焊合室深度对挤压过程进行了模拟,得到了应力、应变、挤压力等各种物理场量的变化规律,并采用有限元法对模具受力及变形情况进行了分析。研究结果表明,焊合室深度对载荷影响不大,但焊合室深度为26mm时质点流速最均匀。模具变形分析结果表明,随着焊合室深度增加,模芯变形程度增大,对应力分布来说,存在一个最佳的焊合室深度。从型材产品质量和模芯变形量综合考虑,应合理设计焊合室深度。     

液力偶合器气液界面追踪数值模拟

部分充液下液力偶合器内部介质运动为离心力场作用下的复杂两相流动,而液相分布形态对涡轮输出特性有着直接影响。为掌握偶合器内液相分布规律,将工作腔内介质运动视为分层流动,采用流体体积法(Volume of fluid,VOF)两相流模型,追踪562型标准桃形腔偶合器内不同工况下的气—液分界面。建立三维周期性流道模型,采用Realizable k-ε湍流模型和压力隐式算子分裂(Pressure-implicit with splitting of operators,PISO)压力耦合算法,并用内部面模拟泵、涡轮间的交互作用,转速比i=1.0和i=0.6时的叶片表面液相分布与文献中试验结果具有高度相似性。仿真结果表明,随泵涡轮间转差增大,气液分界面倾斜加剧,直至形成大的环流,而泵轮叶片压力面液相分布区域增大,吸力面液相减小;低挡圈(R=155 mm)对环流形态影响较小,主要起到限矩作用,而高挡圈(R=175 mm)可抑制大环流的产生。     

冲压泵叶轮后侧腔体结构对泵水力性能的影响

选取MDP64-20型立式多级冲压泵作为研究对象,在泵腔喉部宽度确定的基础上,选取平面隔板、曲面隔板、L型隔板和型线隔板4种腔体形式进行研究。通过数值模拟,经过流场分析、性能曲线分析,比较4种隔板对冲压泵水力性能的影响,确定最佳结构。研究结果表明,在小流量工况下,型线隔板的设计能较好地改善液体流动,减小水力损失;在较大流量工况下,冲压泵效率受到导叶入口处流动、泵腔内部流动两方面综合影响,平面隔板和型线隔板较为优异。     

离心泵泵腔液体压力分布理论计算及验证

准确描述泵腔液体压力分布是研究叶轮盖板力的核心研究问题,也是泵研究领域中的难题。建立泵腔液体流动模型并提出基本假设,将泵腔液体流动视为轴对称二维黏性层流运动,采用数量级比较法,对泵腔液体运动的Navier-Stokes方程简化,并进行积分求得Navier-Stokes方程的近似解析解,推导出设计工况下泵腔液体压力数学模型。在该数学模型计算中,引入势扬程修正系数,解决了泵腔入口液体压力的计算问题,并给出具体确定方法。以IS80-50-315型离心泵为研究对象,在不同叶轮平衡孔直径下,对设计工况下前后泵腔液体压力进行测试和理论计算,对比分析结果表明,两者结果较为一致。还采用2个典型的泵腔液体压力测试实例,进一步验证了设计工况下泵腔液体压力数学模型的可靠性。该研究成果是对经典泵腔液体压力计算公式的补充与完善。     

Research on the valveless piezoelectric pump with Y-shape pipes

A piezoelectric pump with its Y-shape elements is presented. Two Y-shape pipes are fixed outside the chamber serving as an inlet and outlet, with the chamber and a piezoelectric vibrator being the actor. The pump has the potential to be miniaturized and integrated. Eddies occurring in the Y-shape elements are smaller, which is beneficial for the transport of living cells or long-link macromolecules. In this paper, the structure of the pump is first presented. Then, the equations on the change in volume and the mean pressure in the chamber are established, as well as the relation between the flow rate and the working frequency of the piezoelectric vibrator. Moreover, the relation between the mean pressure in the chamber and the working frequency of the piezoelectric vibrator is established. Finally, experiments are carried out to test the characteristics of the pump and to verify the correction of the theory on this pump.     

涡旋液泵内部非稳态流场的数值模拟

采用动网格技术对涡旋液泵内的非稳态流动进行了数值模拟,得到了泵在各个转角下的压力、速度、空泡体积分数,以及进出口流量和监控点的压力参数。结果表明,涡旋液泵内的流动是一种非稳态、非均匀,非对称的流动。动静圈的啮合间隙处因大压差和小流通面积而存在高速射流现象,并在啮合间隙下游出现负压区和空化。泵进口位置的偏移和动盘对腔外流体的推动使左右两个吸液腔的流动不对称,将造成涡盘受力的不平衡。在吸液即将结束时,因涡旋液泵对液体的挤压作用,在大约20°的转角范围内,泵的工作腔内出现极大幅值的压力脉动,严重危害泵的安全可靠运行。     

新型涡旋式多相泵气液增压过程研究与设计理论

提出一种新型涡旋式气液多相混输泵,通过构建变啮合间隙涡旋齿型线,使其所形成的压缩腔存在一条通向排出口方向的内泄漏卸压通道,其增压过程如下:气液介质随着压缩腔容积的减小而压力升高,同时部分介质通过卸压通道被推入到排出口,防止因液相不可压缩而易出现的压缩腔内压力骤增问题。建立涡旋式多相泵的几何理论和工作中带有内泄漏的气液增压过程数学模型,求解得到增压过程中气液状态参数的变化规律。对其工作过程中带有移动边界和气液混合增压的粘性非定常流动进行数值模拟,得到各个工作腔内的速度场和压力场分布,分析含气率、压缩腔容积变化率和啮合间隙等因素对增压过程的影响,形成了新型涡旋式多相泵的设计理论。     

Modernization of the Element 2 mass spectrometer

To perform direct elemental analysis of solids, it is proposed to complement an Element 2 ICP mass spectrometer commercially produced by Thermo Electron Corp. with a glow-discharge ion source based on a hollow cathode. The analyzed sample, in the form of a rod 1.0–2.5 mm in diameter and 15–20 mm in length, is set along the axis of the cathode cavity with an inner diameter of 15–16 mm and a depth of 15 mm. The cathode is placed in a discharge chamber, which, using a viton seal, is substituted for the ICP-source sampler. The use of a plasma mirror and getter evacuation of the source chamber allows a decrease in the source’s hydrocarbon background by a factor of 10³–10⁴. The ion source is evacuated by a mechanical pump of the mass spectrometer and an additional turbomolecular pump. Ion sources in a mass spectrometer are replaced (a change from one analytical method to another) within 5 min. The ion current extracted from the IS allows analysis of conducting solids with a sensitivity at a level of several ppb (10⁻⁷%) at a resolution of the mass spectrometer of 4000. Combining two easily replaceable ICP and GD ion sources in a single high-resolution analyzer significantly extends the analytical capabilities of the Element 2 mass spectrometer. Original Russian Text ? G.G. Sikharulidze, 2009, published in Pribory i Tekhnika Eksperimenta, 2009, No. 2, pp. 98–100.     

往复式机械零部件磨损特性及故障机理探讨

以往复式活塞隔膜泵的曲柄滑块机构为研究对象,当其零部件出现磨损故障时,建立动力学特性的分析模型,为泵的状态监测和故障诊断提供新的理论依据,并探索出故障诊断的新方法,以利于设备诊断技术在往复式机械应用中取得好的效果。     

一种新型单腔双振子压电泵的结构设计和性能试验

为优化单腔双振子压电泵的结构,提高输出性能,设计了一种新型结构的单腔双振子压电泵。将新设计结构同前期设计结构进行了比较,并对两种结构的试验样机进行了输出流量测试。试验显示,新结构的输出流量是前期结构输出流量的2倍,最大流量可达800mL/min。将新结构加工了不同腔体初始容积样机,得到了压缩比对泵输出性能的影响。试验发现,当腔体高度为1.2mm,工作时的压缩比为1/46,此时单腔双振子压电泵整体输出效果最好。分析了单腔双振子压电输送液体和气体时工作特点,得到泵输送液体介质时最佳工作频率点远远低于输送气体介质。