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.

Marcel Salmon博士将在旋转流体流动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影响的涡环的动力学和稳定性方面。涡流通常被称为流体运动的“肌腱和肌肉”。它们的动力学影响了自然界和技术中涉及液体和气体运动的绝大多数过程。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、全球范围的天气现象或海洋环流。背景系统旋转引起科里奥利力。众所周知，与相应的非旋转流动等效物相比，这些力从根本上改变了流体流动的动力学。科里奥利力导致许多非旋转流中不存在的现象，这些现象通常是违反直觉的。背景系统旋转对旋转流体中涡环的动力学和稳定性的影响，在已发表的文献中只存在非常有限的结果。从我们以前的研究中，我们已经知道，科里奥利力的作用不稳定的涡环，他们诱导几个二次流结构。尚待确定的是，究竟是什么原因造成的不稳定，并调查二次流结构如何依赖于独立的系统参数。也就是说，流动如何取决于系统的旋转速度和涡环的生成参数。对于Salmon先生的研究，涡流环将在安装在我们独特的大型旋转转盘设备上的大型充水罐（直径1米，高2米）内产生。当水从一个完全由计算机控制的涡流发生器（一个活塞式的装置）中喷出时，这些环就形成了。Salmon先生将使用我们的钻机进行和分析深入的粒子图像测速（PIV）测量。PIV是一种领先的基于激光的流体流速测量技术。涡流环将从浸没在水箱内的水中的圆形涡流发生器喷嘴喷出。喷嘴安装在旋转轴线上，并且涡流环将被喷射，使得它们在罐内并沿着旋转轴线向下传播。马塞尔将研究流动涡环内部和周围的流场。将数据与非旋转流体中的环的结果进行比较。这些比较将涉及Marcel自己的非旋转流测量数据和非旋转系统中环的文献数据。非旋转系统中涡环的基准数据在相关的科学和工程期刊中有丰富的内容。根据研究的进展情况，该项目还旨在开始调查旋转和非旋转流中非圆形涡环的动力学方面。基本上没有关于这种非圆形涡环动力学的研究。这是因为直到最近，制造复杂的非圆形发生器喷嘴是非常困难的，例如，这种喷嘴使得人们能够在喷射的涡流结构上叠加波浪形起伏。然而，增材制造的最新进展现在使得能够容易地生产这种喷嘴结构。因此，生产这样的喷嘴来进行第一次实验，代表了一个非常有吸引力的新的研究方向，有可能揭示迄今为止完全未知的，基本的，新的流动现象。