Near-contact motion and coalescence of inertial droplets in turbulence: simulations, laboratory experiments and field measurements

主要研究者：柯林斯，兰斯提案编号：1605195提出了一种综合研究方法，包括高保真度计算、实验室实验和现场实验，以理解和预测悬浮在湍流中的液滴的行为。这个问题对于云在大气中的行为非常重要。除了大气应用外，还有许多其他具有工程意义的应用领域，这项工作可能会产生影响，包括柴油发动机，喷雾，雾化，粉末制造和吸入药物治疗。尽管经过半个多世纪的研究，湍流如何提高悬浮液滴的聚结速率仍然存在相当大的不确定性。本研究通过直接数值模拟（DNS），实验和现场测量在广泛的条件下，通过直接测量液滴碰撞/聚结率解决了这种不确定性。研究的重点将是湍流驱动的液滴的聚结率的直接测量。这可应用于广泛的多相流，但对这一建议最重要的应用是处理大气中的云。在某些条件下，云的演化速度比微物理模型所能预测的要快。人们相信大气湍流可以解释云的加速形成。这项研究将汇集三种科学工具的协同组合，用于分析自然湍流现象：DNS;实验室实验;和现场测量。总体目标是在接近参数相似的条件下，从高分辨率DNS和最先进的实验室和现场实验中生成明确的聚结数据。这项调查将包括第一次实验测量的惯性液滴在湍流场，在实验室和自然条件下的聚结速率。只有通过这种集体努力才能实现这一点-仅仅这些技术中的任何一种或两种是不够的。除了拟议工作的工程影响外，拟议活动还包括教育和外联活动，旨在鼓励代表性不足的少数群体进入学院。

PI: Collins, LanceProposal Number: 1605195A comprehensive research approach, involving high fidelity computations, experiments in a laboratory and field experiments is proposed to understand and predict the behavior of drops suspended in turbulent flows. This problem is very important for the behavior of clouds in the atmosphere. In addition to atmospheric applications, there are many other application areas with engineering interest, where this work can have an impact, including diesel engines, sprays, atomization, and powder manufacturing and inhalation drug therapy. Despite more than a half-century of research, there remains considerable uncertainty on how turbulence enhances the coalescence rate of suspended droplets. This study addresses that uncertainty through the direct measurement of droplet collision/coalescence rates in direct numerical simulations (DNS), experiments and in field measurements over a wide range of conditions. The focus of the study will be on the direct measurement of coalescence rates of droplets driven by turbulence. This has application to a wide range of multiphase flows, but the application of primary importance to this proposal is the processing of clouds in the atmosphere. Under certain conditions, clouds evolve faster than microphysical models can predict. It is believed that atmospheric turbulence could explain the acceleration of cloud formation. This study will bring together a synergistic combination of three scientific tools for analyzing natural turbulent flow phenomena: DNS; laboratory experiments; and field measurements. The overarching goal is to generate definitive coalescence data from high-resolution DNS and state-of-the-art laboratory and field experiments under conditions of near parametric similarity. This investigation will include the first experimental measurements of the coalescence rate for inertial droplets in a turbulent flow field, both in the laboratory and in natural conditions. Only with this collective effort can this be achieved - any one or two of these techniques alone will not sufficient. In addition to the engineering impacts of the proposed work, the proposed activities include educational and outreach activities that are targeted towards encouraging underrepresented minorities into the academy.