EAGER: Collaborative Research: Towards Elucidating the Transport Mechanisms of Fine Volcanic Ash

EAGER：合作研究：阐明细火山灰的传输机制

• 批准号: 1160355
• 负责人: Alexander Proussevitch
• 金额: $ 6.63万
• 依托单位: University of New Hampshire
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-15 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1160355&HistoricalAwards=false
• 关键词: EAGER; Collaborative; Research; Towards; Elucidating

This pilot study project addresses the general problem of reducing volcanic ash impact by determining the viability of using novel instrumentation to determine the transport properties of fine volcanic ash in the atmosphere. Volcanic ash is known to present hazards to aviation, infrastructure, agriculture, and human and animal health. With the emergence of aviation in the last 50 years as a key component of global travel and transport, the importance of understanding how long ash is suspended in the atmosphere, and how far it is transported has taken on greater importance. Airborne ash abrades the exteriors of aircraft, enters modern jet engines and melts while coating the interior parts thus causing damage and failure. For example, the 2010 Eyjafjallajökull eruption in Iceland was the most disruptive event in aviation history, with billions of dollars of losses to the aviation industry and global economy. Much of this was unnecessary and better knowledge of the transport of fine ash could minimize such losses in the future. However, present understanding of ash transportation can only account for general air movements, but cannot fully address how much or how long ash remains in the atmosphere, and how much falls out as it travels downwind. To address this lacking, this project focuses on the interaction between ash and atmospheric air by performing experiments of ash flow in a special scientific wind tunnel designed to simulate slow atmospheric currents. The time fine ash stays in the atmosphere depends on its terminal velocity (under the influence of gravity), but current formulations for this are based on raindrops that are relatively large and quasi-spherical, rendering them inapplicable to fine ash, which is smaller (60 μm), non-spherical, and can have complex surface and internal structure. As a result, it is not presently possible to accurately predict the removal rates of fine particles from the volcanic ash clouds that pose aviation and other hazards. To provide observational data to resolve this problem, the novel facilities at UNH and Lehigh University are being used in this pilot study to design experiments for measuring terminal velocities of fine ash with a range of sizes and shapes. The new Flow Physics Facility (FPF) at UNH is the largest low turbulence slow flow wind tunnel in the world designed for academic research. Now, for the first time, it is being used to analyze the aerodynamic properties of fine ash particles in both laminar and turbulent conditions. The Center for Optical Technologies at Lehigh includes state of the art SEMs (stereo and mono) that provide the means for characterizing the shapes and sizes of fine ash to be used in the wind tunnel (FPF). The results of this pilot study will set the stage for subsequent empirical formulations for terminal velocities of the two types of ash particles (simple and compound) that have recently emerged from a previous NSF-supported study of volcanic ash morphology. This will lead to an understanding of the fundamental physics that controls the aerodynamics of volcanic ash in the atmosphere (altitude range from 150 to 1000 mb).

该试点研究项目通过确定使用新型仪器确定大气中细小火山灰的传输特性的可行性，解决了减少火山灰影响的一般问题。众所周知，火山灰会对航空、基础设施、农业以及人类和动物健康造成危害。随着过去 50 年航空业的兴起，成为全球旅行和运输的重要组成部分，了解火山灰在大气中悬浮的时间以及其运输距离变得更加重要。空气中的灰烬会磨损飞机的外部，进入现代喷气发动机并融化，同时覆盖内部部件，从而造成损坏和故障。例如，2010 年冰岛埃亚菲亚德拉冰盖喷发是航空史上最具破坏性的事件，给航空业和全球经济造成了数十亿美元的损失。其中大部分是不必要的，更好地了解细灰的运输可以最大限度地减少未来的此类损失。然而，目前对灰烬输送的理解只能解释一般的空气运动，而不能完全解决灰烬在大气中残留的量或时间，以及顺风传播时有​​多少灰烬掉落。为了解决这一缺陷，该项目通过在一个专门用于模拟缓慢大气流的特殊科学风洞中进行灰烬流动实验，重点研究灰烬与大气之间的相互作用。细灰在大气中停留的时间取决于其终端速度（在重力影响下），但目前的公式是基于相对较大且准球形的雨滴，这使得它们不适用于细灰，因为细灰更小（60米），非球形，并且可以具有复杂的表面和内部结构。因此，目前无法准确预测对航空和其他危害的火山灰云中细颗粒的去除率。为了提供观测数据来解决这个问题，新罕布什尔大学和理海大学的新型设施正在这项试点研究中使用，以设计测量各种尺寸和形状的细灰的终端速度的实验。新罕布什尔大学的新流动物理设施 (FPF) 是世界上最大的低湍流慢流风洞，专为学术研究而设计。现在，它首次被用于分析细灰颗粒在层流和湍流条件下的空气动力学特性。里哈伊光学技术中心拥有最先进的 SEM（立体和单声道），可提供表征风洞 (FPF) 中使用的细灰形状和尺寸的方法。这项试点研究的结果将为随后的两种火山灰颗粒（简单和复合）的最终速度的经验公式奠定基础，这两种火山灰颗粒是最近从先前的 NSF 支持的火山灰形态研究中得出的。这将有助于了解控制大气中火山灰空气动力学的基础物理学（海拔范围从 150 到 1000 mb）。