直管型超声行波微泵驱动参数分析

发布时间：2018-04-05 22:11

本文选题：超声行波　切入点：椭圆运动　出处：《山东大学》2012年硕士论文

【摘要】：随着微加工技术的发展以及其在生物医学领域内应用的迅速扩张,身为微机电(MEMS)技术核心地位的微泵技术也日益成为各国科学家微技术研究的热点,提出了很多基于不同原理,形式各样的微泵模型。其中有一部分已经应用到实际当中。但不论是有阀门微泵还是基于电渗、电水力等原理的无阀门微泵都有其致命弱点,严重限制了应用范围和领域。为此,本文提出了一种新型的无阀微泵,它基于超声行波理论,结构简单、驱动力强、对所驱动的流体种类基本没有限制。超声行波微泵所依据的原理基本有三：1.行波在管壁上传播时,管壁内侧质点做单一方向的椭圆运动,因流体粘度作用,该椭圆运动推动流体流动。2.行波在管壁上传播时引起管壁的蠕动,该蠕动维持一定的形状向单一方向传播,因空间置换推动流体向前流动。3.超声进入流体时在流体和固体界面处形成声流,产生的声辐射力沿一定角度入射推动流体。为对行波微泵做系统的有限元分析,在本文中首先介绍微机电和微流体驱动设备的发展现状,对当前比较流行的微流体驱动器件做简单介绍,包括结构和所依据的原理以及各自的弱点等。然后对本文所探讨的微泵的构成材料做介绍和分析,包括压电振子的构成、压电振子上所加载荷的排列方式、微管道的结构参数及材料参数。利用有限元分析软件对微泵进行建模,并对模型做模态和谐响应分析,确定在最佳模态下的驱动频率。在加上电压载荷后,对模型做瞬态动力学分析,在后处理中观察微泵内壁表面质点的椭圆运动轨迹。最后探讨微泵模型的流固耦合,先对有限元分析软件做流固耦合的方法和步骤做简要分析,尤其是对双向流固耦合的原理、步骤以及CFX软件设置做介绍。然后分别对不同的电压幅值、频率载荷、不同的壁面粗糙度以及不同的流体动力粘度做流固耦合分析。通过对后处理中的结果数据做流线、流速分析得到了一些有用的结论,包括：驱动电压的幅值大小与管口流速成正比,并且当驱动频率等于共振频率时驱动效果最明显；当流体动力粘度小于0.001Pa·s时微流体流速随粘度提高而线性增大,之后则缓慢下降；壁面粗糙度不同,近壁面处流速的峰值会随粗糙度增加而增大,但从图中也可以看出平均流速并未有明显增大。此外,通过CFX后处理得到了微管道中的截面流速矢量图,从图中可以看出在行波驱动作用显著的部分流速分布呈现自微管顶部向下逐渐减慢的特点,而行波驱动作用极微弱的部分流速分布则近似呈现抛物线形状。这些结论为将来对微泵模型的优化和驱动不同流体时微泵参数的选择提供有意义的依据。
[Abstract]:With the development of micro-processing technology and the rapid expansion of its application in the field of biomedicine, the micro-pump technology, which is the core of MEMS technology, has become a hot spot in the research of microtechnology by scientists all over the world, many of which are based on different principles.Various forms of micropump model.Some of them have been applied in practice.However, no matter there is valve micropump or based on electroosmosis, electrohydraulic principle has its fatal weakness, which seriously limits the scope and field of application.In this paper, a new valveless micropump is proposed, which is based on the theory of ultrasonic traveling wave. It is simple in structure and strong in driving force.The ultrasonic traveling wave micropump is based on the principle of 3: 1.When the traveling wave propagates on the pipe wall, the inner particle of the pipe wall moves in a single direction of elliptical motion, which impels the fluid flow. 2 because of the effect of fluid viscosity.The peristalsis of the pipe wall is caused by traveling wave propagating on the pipe wall. The peristalsis maintains a certain shape and propagates in a single direction.The acoustic flow is formed at the interface between the fluid and the solid when the ultrasonic enters the fluid, and the acoustic radiation force is incident at a certain angle to push the fluid forward.In order to analyze the system of traveling wave micropump by finite element method, this paper first introduces the development status of micro electromechanical and micro fluid driving equipment, and briefly introduces the popular micro fluid driver at present.Including the structure and the underlying principles, as well as their respective weaknesses and so on.Then the materials of the micro-pump discussed in this paper are introduced and analyzed, including the structure of the piezoelectric vibrator, the arrangement of the load added on the piezoelectric oscillator, the structural parameters and the material parameters of the micro-pipe.The finite element analysis software is used to model the micropump, and the modal harmonic response is analyzed to determine the driving frequency in the optimal mode.After adding the voltage load, the transient dynamics of the model is analyzed, and the elliptical motion trajectory of the particles on the inner surface of the micropump is observed in the post-processing.Finally, the fluid-solid coupling of the micro-pump model is discussed. Firstly, the method and procedure of fluid-solid coupling are briefly analyzed, especially the principle and steps of two-way fluid-solid coupling, as well as the configuration of CFX software.Then fluid-solid coupling analysis is made for different voltage amplitude, frequency load, different wall roughness and different hydrodynamic viscosity.Some useful conclusions are obtained by streamline the result data of post-processing, including: the amplitude of the driving voltage is proportional to the velocity of the nozzle, and the driving effect is the most obvious when the driving frequency is equal to the resonant frequency;When the hydrodynamic viscosity is less than 0.001Pa s, the flow velocity increases linearly with the increase of viscosity, and then decreases slowly.However, it can also be seen from the diagram that the average velocity does not increase significantly.In addition, the cross-section velocity vector diagram of the microtube was obtained by CFX post-processing. It can be seen from the diagram that the partial velocity distribution, which has significant driving effect on the traveling wave, is gradually slowing down from the top of the microtube.The partial velocity distribution of traveling wave driving is parabola.These conclusions provide a meaningful basis for the optimization of micropump model and the selection of micropump parameters when driving different fluids in the future.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R318.6

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