Name: impacts of free-falling spheres on a deep liquid pool with altered fluid and impactor surface conditions
Uploaded: 2019-02-17T15:00:00
Description: Watch this Scientific Journal Video about Impacts of Free-falling Spheres on a Deep Liquid Pool with Altered Fluid and Impactor Surface Conditions at JoVE.com

作者希望感谢中佛罗里达大学工程与计算机科学学院 (cecs) 为这一项目提供的资金, 乔舒亚·博姆和克里斯·苏奇克为飞溅图像和尼古拉斯·史密斯提供了宝贵的反馈。

1. 配置垂直冲击的实验
<ol><li>将尺寸约为60厘米 x30 厘米 x 36 厘米 (长度 x 重量 x 深度) 的透明水箱填充32升的水, 并在容器内垂直安装仪表尺 ("视觉刻度"), 使底座位于流体顶部, 如图1a 所示。 注: 罐的深度和宽度必须大于实验中使用的最大球体直径的 20倍, 以确保墙体效应可以忽略不计.比这里描述的更高的进入速度将需要更大的坦克深度。第7节讨论了用?...

<ol>
	<li>Watson, D. A., Stephen, J. L., Dickerson, A. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Jet+amplification+and+cavity+formation+induced+by+penetrable+fabrics+in+hydrophilic+sphere+entry.">Jet amplification and cavity formation induced by penetrable fabrics in hydrophilic sphere entry.</a> Physics of Fluids. 30, 082109 (2018).</li><li>Truscott, T. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Cavity dynamics of water entry for spheres and ballistic projectiles. , (2009).</li><li>Truscott, T., Techet, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Water+entry+of+spinning+spheres.">Water entry of spinning spheres.</a> Journal of Fluid Mechanics. 625, 135 (2009).</li><li>Techet, A., Truscott, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Water+entry+of+spinning+hydrophobic+and+hydrophilic+spheres.">Water entry of spinning hydrophobic and hydrophilic spheres.</a> Journal of Fluids and Structures. , 716 (2011).</li><li>Zhao, S., Wei, C., Cong, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Numerical+investigation+of+water+entry+of+half+hydrophilic+and+half+hydrophobic+spheres.">Numerical investigation of water entry of half hydrophilic and half hydrophobic spheres.</a> Mathematical Problems in Engineering. 2016, 1-15 (2016).</li><li>Worthington, A. 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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+tuning+of+a+splash.">The tuning of a splash.</a> Physics of Fluids. 2, 1312-1317 (1990).</li><li>Krishnan, S. R., Seelamantula, C. 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K., Kumar, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Droplet+impact+on+deep+liquid+pools:+Rayleigh+jet+to+formation+of+secondary+droplets.">Droplet impact on deep liquid pools: Rayleigh jet to formation of secondary droplets.</a> Physical Review E. 92, (2015).</li><li>Aristoff, J. M., Truscott, T. T., Techet, A. H., Bush, J. W. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+water+entry+cavity+formed+by+low+bond+number+impacts.">The water entry cavity formed by low bond number impacts.</a> Physics of Fluids. 20, 091111 (2008).</li><li>Aristoff, J., Bush, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Water+entry+of+small+hydrophobic+spheres.">Water entry of small hydrophobic spheres.</a> Journal of Fluid Mechanics. 619, 45-78 (2009).</li><li>Aristoff, J., Truscott, T., Techet, A., Bush, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+water+entry+of+decelerating+spheres.">The water entry of decelerating spheres.</a> Physics of Fluids. 22, (2010).</li><li>Truscott, T., Epps, B., Techet, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unsteady+forces+on+spheres+during+free-surface+water+entry.">Unsteady forces on spheres during free-surface water entry.</a> Journal of Fluid Mechanics. 704, 173-210 (2012).</li><li>Truscott, T. 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该协议描述了在深层液池中调查自由落体球的实验设计和最佳实践。我们首先强调配置垂直影响实验所需的步骤。使用足够大的飞溅区域创建理想的飞溅环境非常重要, 这样墙体效果可以忽略不计9, 并且需要适当的视觉尺度来提取运动学12、13、14 , 15,16,<...

固体物体对深液池1的垂直撞击所产生的飞溅动力学特性适用于军事、海军和工业应用, 如弹道导弹进水和海面着陆 2, 3,4,5。第一次进水研究是在一个多世纪前的 6、7日进行的。在这里, 我们建立了明确的深入协议和最佳做法, 以便在进水调查中取得一致的结果。为了辅助有效的实验设计, 提出了一种卫生条件维护、界面条件改变、无量纲参数控制、冲击表面化学修饰、飞溅运动学可视化等方法。
自由落体亲水球体对静止流体的垂直影响在低速时没有空气堵塞的迹象.我们发现, 在流体表面上放置薄型可穿透织物会导致空腔形成, 原因是强制流动分离1。表面上少量的织物放大了在一系列中等韦伯数上的飞溅, 而足够的分层衰减飞溅, 因为球体克服了流体入口1的阻力。在本文中, 我们解释了适用于确定材料强度对亲水球进水的影响的协议。
从疏水冲击器形成的凹槽显示了一个发育良好的飞溅冠的提升, 其次是原始射流在地表上方的突起, 而与他们喜欢水的对应者相比。在这里, 我们提出了一种方法, 以实现防水通过化学改性的水面亲水球。
随着高速摄像机的出现, 飞溅可视化和表征变得更加容易实现。即使如此, 该领域的既定标准也要求使用与旅行的主轴正交的单个相机。我们表明, 使用额外的高速摄像头的架空视图是必要的, 以判断球体罢工的预期位置。

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impacts of free-falling spheres on a deep liquid pool with altered fluid and impactor surface conditions

球体对清洁水的垂直影响一直是许多水进入调查的主题, 其特征是腔的形成、飞溅冠的提升和沃辛顿的喷射稳定性。在这里, 我们建立了实验协议, 以检查飞溅动力学时, 光滑的自由落体球不同的润湿性, 质量和直径影响一个深液池的自由表面修改薄渗透织物和液体表面活性剂。进水调查为研究复杂流体力学提供了可访问的、易于组装和执行的实验。我们在此提出了一个可调谐的协议, 用于表征飞溅高度、流量分离指标和冲击运动学, 以及如果重现我们的方法可能会获得的代表性结果。当特征飞溅尺寸保持在约0.5 米以下时, 该方法适用。然而, 该协议可以适应更大的冲击释放高度和冲击速度, 这预示着将结果转化为海军和工业应用的好兆头。

这一既定协议允许遵守沃辛顿喷气式飞机所产生的垂直撞击范围内的韦伯数<img alt="Equation 5" src="/files/ftp_upload/59300/59300eq5.jpg"> , 如图2c 所示。这些结果发表在 watson 等人的文章1 中, 可供用于生成本文所示数据的确切实验条件参考。我们关注的是在自由液体表面上方突出的流体的窄拉长膜。在图 3中, 我们展示了?...

Watch this Scientific Journal Video about Impacts of Free-falling Spheres on a Deep Liquid Pool with Altered Fluid and Impactor Surface Conditions at JoVE.com

Impacts of Free-falling Spheres on a Deep Liquid Pool with Altered Fluid and Impactor Surface Conditions

该协议演示了自由落体进水实验的基本实验结构。讨论了用可渗透织物改变液体表面的方法、化学非润湿球体的制备以及飞溅可视化和数据提取的步骤。

自由落体对变液和冲击物表面条件下深层液池的影响

Vertical impacts of spheres on clean water have been the subject of numerous water entry investigations characterizing cavity formation, splash crown ...

该协议演示了自由落体水注入实验。讨论了穿透织物的液体表面的交替、新兴球体中化学的制备、飞溅可视化和数据提取。这些技术提供了对基础流体动力学研究的洞察，旨在了解固体物体和流体体之间的面间相互作用。展示这个程序的将是约书亚·博姆和杰里米·斯蒂芬，来自艾伯塔省的本科生。在整个过程中佩戴工业级硝酸盐手套，以避免用皮肤油污染水和冲击器。开始用自来水和洗涤剂彻底清洁透明水箱。然后用32升自来水装满。用 99%异丙醇清洁两个公制标尺，让它们干燥一分钟。将一把尺子安装到水箱前部，底座只是触摸水。将第二把尺子垂直固定在水下。然后在水箱上固定铰链平台，使平台与上述水尺位于与罐前部相同的深度平面内。将平台调整到所需的最大落点高度，然后将多 LED 灯连接到铰接臂上，将灯放在油箱上方和前面，以完全照亮平台下的初始区域。在油箱背面设置黑屏，以帮助进行飞溅和空腔可视化。将清洁无油减震器（如封闭式电池海绵）放在油箱底部，并用清洁的重量将吸油器放在位上。接下来，安装一个高速摄像机，与油箱朝向，与液体表面一样。如果需要，请将触发器开关连接到摄像机。将摄像机连接到计算机，并配置摄像机的帧速率至少为每秒 1，000 帧。选择所需的分辨率，将快门速度设置为每帧一秒。如果适用，将触发模式设置为"结束"。接下来，用99%的异丙醇清洁小勺和多氧化物甲醇球，去除皮肤油和其他污染。让球体和勺子干燥一分钟。预制测试并调整摄像机位置、对焦和分辨率，以实现初始事件的最佳可视化质量。然后用勺子取回球体，用异丙醇清洁球体和勺子。当准备开始实验时，开始拍摄坦克。将铰链平台抬到位，将干净的干球放在平台上。松开平台的底座，将球体放入油箱中。然后停止拍摄，保存视频文件，并修剪视频，只显示飞溅事件。当准备继续下一次测试时，使用勺子检索球体。用异丙醇清洁球体，让它干燥一分钟，然后再重复测试。实验完成后，清空油箱，让它干燥。为测试准备可穿插织物，请将所需的织物分离成方形或圆形的层，并使用 Vernier 卡钳测量干织物的压缩厚度。设置实验时，在油箱上安装第二个高速摄像机，以提供影响织物的球体的自上而下视图。使用 BNC 电缆将水平摄像机输出连接到架空摄像机输入端子。将触发开关连接到水平摄像机。然后使用以太网电缆将两个摄像机连接到连接到摄像机计算机的脱机路由器。像往常一样对两个摄像机进行对焦和配置。当准备预制实验时，轻轻地将干织物放在罐中液体表面。确保织物在审判开始前不会开始下沉。使用清洁、无油的铲料将织物定位在铰链平台下方。在设置碰撞之前，使用触发开关使用两个摄像机同时开始拍摄飞溅区域。碰撞后立即拆下织物。如果织物碎片对冲击和刮擦不能手动收集空和清洁罐后，每次试验，以确保所有织物被移除。开始准备化学疏水球体，将聚氧化物薄荷球放入丙烯酸支架中。表面涂层的定位球体是该协议最困难的方面。定位由层涂层丙烯酸板控制，其孔比球体稍宽。用疏水基面喷洒球体，距离约 15 至 30 厘米，而不会浸泡球体表面。接下来，用疏水性上衣喷洒球体，从约15至30厘米远，无需浸泡表面，让它干燥一到两分钟。以相同的方式涂抹两到三层涂层。让球体干燥 30 分钟，供轻用或约 12 小时充分使用。当预制冲击测试让球体在每次试验后完全干燥，而不是用异丙醇冲洗球体。疏水涂层将在约20次试验后降解。要重复使用此球体，请用 99%异丙醇去除涂层，然后重新应用前文所述的底涂层和顶部涂层。要开始分析，将飞溅事件的高速视频导入视频分析软件。使用缩放工具根据标尺的可见区域以厘米为单位设置缩放值。通过视频前进，找到一个合适的框架，显示飞溅冠提升和空气陷阱。测量飞溅冠高度、型腔宽度和型腔深度。使用角度测量工具确定分离角度。在视频中进一步寻找一个合适的帧，显示沃辛顿喷气机形成和测量沃辛顿喷气机的高度。最后，使用自动跟踪功能提取冲击器的时间位置和速度日期。如果跟踪被中断，请使用手动跟踪，直到自动跟踪可以恢复。在这里，此过程用于评估织物对垂直冲击飞溅的影响。一层飞溅高度相对于没有织物的飞溅高度被放大。两层飞溅高度大致相当于没有织物的飞溅高度。飞溅被严重衰减与三和四层。韦伯数对影响单层织物的球体的空腔深度、飞溅地面高度和型腔宽度的最小变化。在水下跟踪球体垂直位置，可以观察水下速度随织物的每个增加层而进一步下降。研究者必须特别注意实验期间卫生实验条件的维护，以取得一致有效的结果。此技术不限于此处介绍的材料，并且可以使用具有类似功能和能力的材料进行。通过引入高架储层（如西环），可以提高此程序，以调查液滴对固体或液体表面的垂直影响。该协议还可以在更大范围内进行预格式，以泛泛而广的冲击速度和增加无维参数的范围，这对于海军和工业应用来说都很顺利。

Research

Education

JoVE Core

JoVE Journal

Mechanical Engineering

Engineering

Unit 1

Kinetics of a Particle: Impulse and Momentum

SCIENTISTS IN ACTION

Visualization of High Speed Liquid Jet Impaction on a Moving Surface

高速喷液嵌塞对移动表面的可视化

Two apparatuses for examining liquid jet impingement on a high-speed moving surface are described: an air cannon device (for examining surface speeds ...

科研

工程学

Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment

硅表面润湿性的选择区域改性脉冲紫外激光照射在液体环境

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of ...

Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron

烧蚀材料在试验过程中等离子体发生器发射光谱边界层研究

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution ...

Preparation of Liquid-exfoliated Transition Metal Dichalcogenide Nanosheets with Controlled Size and Thickness: A State of the Art Protocol

与尺寸可控液体剥离的过渡金属二硫属化物纳米片和厚度的制备：艺术议定书的国家

We summarize recent advances in the production of liquid-exfoliated transition metal dichalcogenide (TMD) nanosheets with controlled size and thickness. ...

Pool-Boiling Heat-Transfer Enhancement on Cylindrical Surfaces with Hybrid Wettable Patterns

在圆柱面池沸腾传热强化与混合可湿性模式

In this study, pool-boiling heat-transfer experiments were performed to investigate the effect of the number of interlines and the orientation of the ...

Preparation and High-temperature Anti-adhesion Behavior of a Slippery Surface on Stainless Steel

不锈钢滑面的制备及高温抗粘接性能研究

Anti-adhesion surfaces with high-temperature resistance have a wide application potential in electrosurgical instruments, engines, and pipelines. A ...

Effective Analysis of Human Exposure Conditions with Body-worn Dosimeters in the 2.4 GHz Band

2.4 GHz 波段人体磨损剂量计暴露条件的有效分析

A well-defined experimental procedure is put forward to evaluate maximum exposure conditions in a worst-case scenario whilst avoiding the uncertainties ...

Visually Based Characterization of the Incipient Particle Motion in Regular Substrates: From Laminar to Turbulent Conditions

从层流到湍流条件下的规则基底表面初始粒子运动的可视化表征

Two different experimental methods for determining the threshold of particle motion as a function of geometrical properties of the bed from laminar to ...

Fabrication of Superhydrophobic Metal Surfaces for Anti-Icing Applications

防结冰用超疏水性金属表面的制备

Several ways to produce superhydrophobic metal surfaces are presented in this work. Aluminum was chosen as the metal substrate due to its wide use in ...

Microparticle Manipulation by Standing Surface Acoustic Waves with Dual-frequency Excitations

双频激励下驻面声波的微粒操纵

We demonstrate a method for increasing the tuning ability of a standing surface acoustic wave (SSAW) for microparticles manipulation in a lab-on-a-chip ...