【作者】 杨哲；

【导师】 吴化平；

【作者基本信息】 浙江工业大学 ， 机械工程， 2019， 硕士

【摘要】 在大自然和人们的日常生活中,气泡的定向输运现象时时刻刻都在发生,并发挥着日益重要的作用。关于气泡在平面的输运已经进行了较多的理论研究和试验分析,但关于曲面这一更加普遍的存在,特别是螺旋曲面,却缺乏系统的理论和实验研究。螺旋曲面在结构上具有连续不对称性,即曲率因位置不同而连续发生变化,适合气泡的持续输运。但是,对于气泡的输运,螺旋曲面本身也存在一些不足,诸如当气泡靠近曲率中心时,输运速度较快;当气泡接近曲率边缘时,输运速度较慢,特别是曲率梯度较小的曲率边缘,运动速度接近0,近乎于停滞状态。为解决这一问题,本文采用理论与实验相结合的方式,从热力学角度出发,推导了在螺旋曲面的上气泡的自由能和驱动力,并结合实验现象,分析了气泡在螺旋曲面基底上的定向输运行为。利用楔形与曲率相结合的方法,改善了气泡接近曲率边缘时运动速率较小的状况,同时探讨分析了气泡在水下输运所考虑的各种问题。将楔形湿滑螺旋曲面应用到水下,实现了气泡的反重力输运、反浮力输运、气泡微反应演化器的应用;将楔形螺旋曲面应用到析氢反应中,实现了气泡从反应区到水面的定向输运,提高了析氢反应速率,避免了气泡释放到水中时的副作用。本文的主要研究成果如下:(1)详细的研究了螺旋曲面结构对气泡受力大小和输运速度的影响。首先建立热力学理论模型推导出气泡在螺旋曲面的能量关系式和受力关系式;其次,分析了材料润湿性和螺旋曲面曲率梯度大小对气泡在螺旋曲面输运速度的影响;最后通过实验分析了气泡的运动过程、气泡最小体积的限制、气泡体积对整体输运速度的影响、气泡速度随所处位置的变化,验证了理论模型的正确性。(2)将楔形结构与螺旋曲面结构相结合,解决了楔形高速输运与长距离输运的不共存问题,实现了螺旋曲面气泡输运的高起始加速度。研究了气泡在楔形螺旋曲面的受力形式,推导出气泡的受力表达式。具体分析了楔形平面拉普拉斯力和螺旋曲面曲率梯度力二者协同作用提高气泡输运速度的机理;详细分析了螺旋距离参数a、楔角参数α、接触角θ对气泡自输运驱动力的影响,进而实现对速度的调控。通过数控车床机械加工和镜面抛光处理制备出楔形曲面,并对实验结果加以分析,进一步验证了理论的正确性。(3)将楔形螺旋曲面结构引入水下,以空气气泡研究结果为基础,研究气泡在水下楔形螺旋曲面结构的润湿性质和运动状态,探讨了气泡在水下楔形螺旋曲面结构的受力状态。通过理论分析,制备了湿滑性楔形螺旋曲面结构,研究了楔形螺旋曲面结构参数(螺旋距离参数a、楔角参数α)对气泡驱动力和输运速度的影响,以及水下气泡湿滑剂的润湿性、湿滑剂的表面张力和粘度对气泡输运速度的影响。结合理论分析和实验结果制备了楔形螺旋曲面铜铝电极,解决了微泡在电极表面的黏附问题,实现了气泡在电极的快速脱离,提高了电化学反应速率和危险性气体的收集。(4)从仿生出发,制备了楔形锥螺旋曲面,实现了气泡在空气环境中和水环境中的轴向运输,包括反重力输运和反浮力运输,打破了浮力输运的限制,并设计了气泡微反应演化器,将楔形锥螺旋曲面结构参数化处理,分析气泡的受力形式,结合实验分析楔形锥螺旋曲面的结构参数对输运速度的影响。更多还原

【Abstract】 In nature and people’s daily lives,the directional transport of bubbles is constantly occurring and plays an increasingly important role.There have been many theoretical studies and experimental analyses on the transport of bubbles in the plane,but there is a lack of systematic theoretical and experimental research on the more common existence of curved surfaces,especially spiral surfaces.The spiral surface has a continuous asymmetry in structure,that is,the curvature changes continuously due to different positions,and is suitable for continuous transport of bubbles.However,for the transport of bubbles,the spiral surface itself also has some shortcomings,such as when the bubble is close to the center of curvature,the transport speed is faster;when the bubble is close to the edge of the curvature,the transport speed is slower,especially the curvature gradient is smaller.At the edge of the curvature,the speed of motion is close to zero,which is close to the stagnation state.In order to solve this problem,this paper combines theory and experiment,and derives the free energy and driving force of the bubble on the spiral surface from the perspective of thermodynamics.Combined with the experimental phenomenon,the directional transport operation of the bubble on the spiral curved base is analyzed.The combination of wedge shape and curvature improves the movement rate of the bubble near the edge of curvature,and discusses the various problems considered by the bubble in underwater transportation.The wedgeshaped wet-slip spiral surface is applied to the underwater to realize the application of anti-gravity transport,anti-buoy force transport and bubble micro-reaction evolution of the bubble;Applying the wedge-shaped spiral surface to the hydrogen evolution reaction,the directional transport of the bubble from the reaction zone to the water surface is realized,the hydrogen evolution reaction rate is increased,and the side effects of the bubble release into the water are avoided.The main research results of this paper are as follows:(1)The influence of the spiral curved structure on the force of the bubble and the transport speed is studied in detail.Firstly,the thermodynamic theory model is established to derive the energy relation and force relationship of the bubble on the surface.Secondly,the influence of the material wettability and the curvature gradient of the spiral surface on the transport speed of the spiral surface is analyzed.Finally,the motion process of the bubble,the limitation of the minimum volume of the bubble,the influence of the bubble volume on the overall transport speed,and the change of the bubble velocity with the position are analyzed by experiments.The correctness of the theoretical model is verified.(2)Combining the wedge-shaped structure with the spiral curved surface structure solves the problem of non-coexistence of wedge-shaped high-speed transport and longdistance transport,and achieves a high initial acceleration of spiral curved bubble transport.The force form of the bubble on the wedge-shaped spiral surface is studied,and the force expression of the bubble is derived.The mechanism of the synergistic action of the wedge-shaped plane Laplacian force and the spiral surface curvature gradient force to improve the bubble transport velocity is analyzed in detail.The spiral distance parameter a,the wedge angle parameter α,and the contact angle θ are analyzed in detail for the bubble self-transport drive.The influence of force,and then the regulation of speed.The surface of the wedge-shaped curvature structure was prepared by lathe machining and mirror polishing,and the experimental results were analyzed to further verify the theoretical correctness.(3)Introducing the wedge-shaped spiral surface structure into the water,based on air bubble research results,study the wetting properties and motion state of the bubble wedge-shaped spiral surface structure under water.The force state of the bubble-shaped spiral curved surface structure under water is discussed.Through the theoretical analysis,the wet-slip wedge-shaped spiral surface structure was prepared.The influence of the wedge-shaped spiral surface structure parameters(spiral distance parameter a,wedge angle parameter α)on the bubble driving force and transport speed,and the underwater bubble slip agent were studied.The wettability,the surface tension of the slip agent and the effect of viscosity on the bubble transport rate,and combined with theoretical analysis and experimental results,a wedge-shaped spiral curved copper-aluminum electrode was prepared,which solved the problem of adhesion of microbubbles on the electrode surface,realized the rapid detachment of bubbles at the electrode,and improved the electrochemical reaction rate and the collection of dangerous gases.(4)Starting from bionics,a wedge-shaped spiral structure was prepared,which realized the axial transportation of air bubbles in the air environment and the water environment,including anti-gravity transport and anti-buoy force transport,breaking the limitation of buoyancy transport,the bubble micro-reaction evolution is designed.The wedge-shaped spiral structure is parameterized,and the force form of the bubble is analyzed.The influence of the structural parameters of the wedge-shaped spiral surface on the transport speed is analyzed..更多还原