Magnetic Resonance Imaging of two-phase systems

直接或间接地，人类总是会遇到气泡和喷雾：通过驾驶柴油车或乘坐公共汽车（柴油燃料喷雾），通过使用水电/热电/核电厂的电力（气泡侵蚀水电厂涡轮机，是冷却系统腐蚀的活性剂）或通过吃蔬菜（最有可能用杀虫剂喷雾处理）。 无论您是设计一个地球工程项目来大规模喷洒盐水以对抗全球变暖，还是建造一个气泡塔反应器来从藻类中生产生物燃料，对气泡和液滴过程的理解都至关重要。 为了发展这种理解，可靠的，定量测量气泡流和喷雾液滴是必要的。泡状流和喷雾研究中常用的测量技术是基于光学的。然而，由于气泡和液滴都反射光，光学技术在高气泡和喷雾密度下变得无效。 该项目建议使用磁共振成像（MRI）研究气泡流和喷雾。MRI通常用作临床诊断模式，由于其作为非侵入性的固有三维方法的优点，MRI也正在稳步成为材料研究中的重要工具，该方法可以对各种物理和化学参数敏感，并且不需要任何光学透明度。 在泡状流中，测量微气泡尺寸、流动性和气泡诱导混合的新技术将在泡罩塔原型上开发和评估。在喷雾研究中，将在MRI扫描仪内建造喷雾室。将研究用MRI研究液滴蒸发、大小、速度和其他参数的新方法，允许在以前无法通过其他方法获得的区域中在非常短的时间尺度上成像。

Directly or indirectly, humans encounter bubbles and sprays all the time: by driving a diesel car or riding a bus (diesel fuel sprays), by using electricity from hydro/heat/nuclear plants (bubbles erode hydroplant turbines and are active agents of corrosion in cooling systems) or by eating vegetables (most likely treated with insecticide sprays). Whether you design a geo-engineering project to spray salt water on a massive scale to fight global warming or build a bubble column reactor to produce biofuel from algae, an understanding of processes involving bubbles and droplets is of fundamental importance. To develop that understanding, reliable, quantitative measurements of bubbly flows and droplets in sprays are necessary. Commonly employed measurement techniques in studies of bubbly flows and sprays are optics-based. However, as both bubbles and droplets reflect light, optical techniques become ineffective at high bubble and spray densities. This project proposes to use Magnetic Resonance Imaging (MRI) for studies of bubbly flows and sprays. Commonly employed as a diagnostic modality in clinics, MRI is also steadily becoming an essential tool in studies of materials because of its advantages as a non-invasive, inherently 3-dimensional method which can be sensitive to a wide variety of physical and chemical parameters and which does not require any optical transparency. In bubbly flows, new techniques of measuring microbubble sizes, mobility and bubble-induced mixing will be developed and evaluated on bubble column prototypes. In spray research, a spray chamber will be built inside an MRI scanner. New approaches to study droplet evaporation, size, velocities and other parameters with MRI will be investigated, permitting imaging at very short time scales in the regions previously inaccessible by other methods.