Advanced Laser Diagnostics Investigating the Fluid Mechanics of Primary Breakup

先进激光诊断研究初级破裂的流体力学

• 批准号: 2879517
• 金额: --
• 依托单位: University of Edinburgh
• 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-2879517
• 关键词: Advanced; Laser; Diagnostics; Investigating; Fluid

Spray systems are widely used in various industries, from fuel injection to pharmaceuticals, and improving their efficiency requires a deeper understanding of the primary breakup process. When a liquid core exits a nozzle, it breaks up into larger, primary drops, which then further divide into smaller droplets in a process called primary breakup. However, this mechanism is the least well-understood area of spray systems, and current numerical models have to rely on significant simplifications. The lack of knowledge about primary breakup is largely attributed to insufficient experimental data of sprays at higher Reynolds (Re) and Weber (We) numbers, this is due to the high optical density in the near-field region of a spray where this mechanism occurs. Thus, making imaging the liquid-gas interfaces (LGIs) at primary breakup difficult. To address this challenge, this PhD project aims to use state-of-the-art laser diagnostic tools, specifically two-photon light-induced fluorescence (2p-LIF) and ballistic imaging. Both ballistic imaging and 2p-LIF have been successfully employed to visualise high optical density regions The efficacy of breakup can be determined by resolving the forces acting on primary drops, which can be achieved using wavelet-based optical flow (wOF) techniques. The objective of this project is to develop an accurate wOF platform to be used with advanced laser diagnostic tools to determine the velocity and acceleration components at LGIs of the primary drops. These sprays will be generated from various isolated breakup mechanisms, including shear, turbulence, and cavitation, using a specially designed spray facility. The facility will flow liquid through custom-designed nozzles at different injection pressures and will be capable of providing a wide variety of Re, We, and cavitation (Ca) numbers. The PhD project comprises three sections, with the first two laying the groundwork for the third. Firstly, the development of a wOF platform to accurately estimate the velocity and acceleration of atomising sprays will be undertaken, using synthetic data from direct numerical simulation of atomising spray databases supplied by partners at RWTH Aachen University. Secondly, a spray facility will be designed to isolate the various breakup mechanisms highlighted earlier, with various liquids and nozzle geometries. Finally, the spray facility will be used to produce mildly atomising to highly atomising sprays for each breakup configuration, visualising the primary breakup process using 2p-LIF or ballistic imaging and coupled with the wOF platform developed to resolve the velocity and acceleration components to determine the efficacy of each breakup mechanism. The project aims to address the challenge of insufficient experimental data of the primary breakup of sprays at higher Reynolds and Weber numbers, providing new insights and data for the wider spray community to further aid in the modelling of spray systems. The data from the fundamental spray facility will serve as a basis of understanding for further research in the PRIME project proposed by Dr Brian Peterson.

喷雾系统广泛应用于从燃料喷射到制药的各个行业，提高其效率需要对主要破碎过程有更深入的了解。当液体核心离开喷嘴时，它分裂成较大的初级液滴，然后在称为初级分裂的过程中进一步分裂成较小的液滴。然而，这一机制是喷雾系统最不容易理解的领域，目前的数值模型必须依赖于显着的简化。缺乏知识的初级破碎在很大程度上是由于在较高的雷诺数（Re）和韦伯数（We）的喷雾的实验数据不足，这是由于高的光密度在近场区域的喷雾，这种机制发生。因此，使成像的液体-气体界面（LGIs）在初级分裂困难。为了应对这一挑战，该博士项目旨在使用最先进的激光诊断工具，特别是双光子光诱导荧光（2 p-LIF）和弹道成像。弹道成像和2 p-LIF都已成功地用于可视化高光学密度区域。可以通过解析作用于初始液滴的力来确定破碎的功效，这可以使用基于小波的光流（wOF）技术来实现。该项目的目标是开发一个精确的wOF平台，与先进的激光诊断工具一起使用，以确定初始液滴在LGIs处的速度和加速度分量。这些喷雾将使用专门设计的喷雾设施从各种孤立的破碎机制（包括剪切、湍流和空化）产生。该设施将使液体以不同的喷射压力流过定制设计的喷嘴，并能够提供各种Re，We和空化（Ca）数。博士项目包括三个部分，前两部分为第三部分奠定基础。首先，开发一个wOF平台，以准确地估计雾化喷雾的速度和加速度将进行，使用直接数值模拟的雾化喷雾数据库由合作伙伴提供的合成数据在RWTH亚琛大学。第二，将设计一个喷雾设施，以隔离各种破碎机制强调前面，各种液体和喷嘴的几何形状。最后，喷雾设施将用于为每个破碎配置产生轻度雾化到高度雾化的喷雾，使用2 p-LIF或弹道成像可视化主要破碎过程，并与开发的wOF平台相结合，以解析速度和加速度分量，以确定每个破碎机制的功效。该项目旨在解决在较高雷诺数和韦伯数下喷雾初级破碎实验数据不足的挑战，为更广泛的喷雾界提供新的见解和数据，以进一步帮助喷雾系统建模。来自基本喷雾设施的数据将作为Brian Peterson博士提出的PRIME项目进一步研究的基础。