Experimental investigation of the effects of background system rotation on the flow dynamics of circular vortex rings and non-circular vortex loops

背景系统旋转对圆形涡环和非圆形涡环流动动力学影响的实验研究

• 批准号: 2871822
• 金额: --
• 依托单位: University of Warwick
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2871822
• 关键词: Experimental; investigation; effects; background; system

For his PhD Mr Marcel Salmon will be conducting an experimental research project in the area of rotating fluid flows. In particular, the project will investigate aspects of the dynamics and the stability of vortex rings subject to background system rotation. Vortices are often referred to as the 'sinews and muscles' of fluid motion. Their dynamics affect the vast majority of all processes in nature and technology that involve liquids and gases in motion. Examples include, for instance, liquid-mixing processes in industrial production processes, vortices encountered in flow around cars or aeroplanes, weather phenomena or ocean circulation of global scale. Background system rotation induces Coriolis forces. These forces are well known to fundamentally alter the dynamics of fluid flows in comparison to the corresponding, non-rotating flow equivalent. Coriolis forces result in many, often counter-intuitive, phenomena absent in non-rotating flows. In the published literature there only exists a very limited number of results on the effects that background system rotation has on the dynamics and the stability of vortex rings in a rotating fluid. From our previous research, we already know that Coriolis forces act destabilizing on vortex rings and that they induce several secondary flow structures. What remains to be established is what exactly causes the destabilization and to investigate how the secondary flow structures depend on the independent system parameters. That is, how the flow depends on the rotational velocity of the system and the generation parameters of the vortex rings. For Mr Salmon's study vortex rings will be generated inside a large water-filled tank (diameter 1m, height 2m) mounted on our unique large-scale rotating-turntable facility. The rings form when water is ejected from a fully computer-controlled vortex-generator, a nozzle-piston arrangement. Mr Salmon will use our rig to conduct and analyse in-depth Particle-Image-Velocimetry (PIV) measurements. PIV is the leading, laser-based technology to perform velocity measurements in fluid flows. The vortex rings will be ejected from the circular vortex generator nozzle which is submerged in the water inside the tank. The nozzle is mounted on the axis of rotation and the vortex rings will be ejected such that they propagate downwards within the tank and along the rotational axis. Marcel will study the flow field within and surrounding the travelling vortex rings. The data will be compared to results for rings in non-rotating fluids. These comparisons will involve data from Marcel's own measurements for non-rotating flow and literature data for rings in non-rotating systems. Benchmark data for vortex rings in non-rotating systems are abundant in the relevant scientific and engineering journals. Depending on the progress of the research the project also aims to begin investigating aspects of the dynamics of non-circular vortex loops, in rotating and non-rotating flow. There exists essentially no research on the dynamics of such non-circular vortex loops. That is so, because until recently, it was very difficult to manufacture complex, non-circular generator nozzles which, for instance, enable one to superpose wavy undulations on the ejected vortex structure. However, the recent advances in additive manufacturing now enable producing such nozzle structures easily. Therefore, producing such nozzles to perform first experiments with them represents a highly attractive new research direction that has the potential to uncover hitherto entirely unknown, fundamental, new flow phenomena.

对于他的博士学位，马塞尔·萨蒙（Marcel Salmon）先生将在旋转流体流动的领域进行实验研究项目。特别是，该项目将研究受背景系统旋转的动力学和涡旋环的稳定性的各个方面。涡流通常称为流体运动的“正弦和肌肉”。它们的动态影响涉及运动中液体和气体的自然界和技术中的绝大多数过程。例如，例如，工业生产过程中的液体混合过程，在汽车或飞机周围的流动中遇到的涡流，天气现象或全球尺度的海洋循环。背景系统旋转诱导科里奥利力。众所周知，与相应的非旋转流相比，这些力从根本上改变了流体流动的动力学。科里奥利的力导致非旋转流中缺乏许多，通常是违反直觉的现象。在已发表的文献中，仅存在对背景系统旋转对旋转流体中涡流环的动力学和稳定性的影响的结果非常有限的结果。从我们以前的研究中，我们已经知道科里奥利部队在涡旋环上发挥了不稳定的作用，并且它们诱导了几种二级流结构。尚待建立的要确切导致不稳定的是什么，并研究二级流结构如何依赖于独立的系统参数。也就是说，流程如何取决于系统的旋转速度和涡旋环的生成参数。对于先生，鲑鱼的研究涡流环将在我们独特的大型旋转可转移设施上安装在一个充满水的水箱（直径1m，高度为2m）内。从完全计算机控制的涡流生成器中弹出水时，将形成环，这是一种喷嘴活塞布置。 Salmon先生将使用我们的钻机进行和分析深入的粒子形象 - 丝毫图（PIV）测量。 PIV是基于激光的领先技术，可在流体流中执行速度测量。涡旋环将从圆形涡流发生器喷嘴中弹出，该喷嘴被浸入水箱内的水中。喷嘴安装在旋转轴上，涡旋环将被弹出，以使它们在水箱内和旋转轴内向下传播。马塞尔（Marcel）将研究旅行涡流环内外的流场。将数据与非旋转流体中环的结果进行比较。这些比较将涉及来自Marcel自己的非旋转流量和非旋转系统中环的文献数据的数据。在相关的科学和工程期刊中，非旋转系统中涡旋环的基准数据丰富。根据研究的进展，该项目还旨在开始研究非圆形涡流环，旋转和非旋转流动的动力学方面。基本上没有关于这种非圆形涡旋循环动力学的研究。就是这样，因为直到最近，制造复杂的，非圆形发电机喷嘴非常困难，例如，这使得可以在弹出的涡流结构上进行超级波动的波动。但是，添加剂制造的最新进展现在可以轻松生产此类喷嘴结构。因此，产生这样的喷嘴与它们进行首次实验是一个非常有吸引力的新研究方向，有可能发现迄今完全未知的，基本的，新的流动现象。