A novel experimental chamber for the characterization of free-falling particles in volcanic plumes
A novel experimental chamber for the characterization of free-falling particles in volcanic plumes
复制标题
DOI：
10.1063/5.0093730
复制
发表时间：
2022-07-01
影响因子：
1.6
通讯作者：
James, Mike R.
中科院分区：
文献类型：
--
作者：
Capponi, Antonio;Lane, Steve J.;James, Mike R.
火山羽流对健康和社会构成危害，对航空尤其危险。灾害缓解依赖于预测烟羽随时间在大气中的扩散。预报的准确性取决于我们对颗粒扩散和沉积过程的了解，以及模型输入参数的准确性，例如大气中火山颗粒(即火山灰)的初始颗粒尺寸分布和浓度。然而，我们对这些过程的低估和对输入参数的准确量化仍然是烟羽扩散模拟中不确定性的主要来源。直接采集火山羽流样品通常是不切实际的，但可以在实验室中限制颗粒沉积。在这里，我们描述了一种用于研究自由落体火山颗粒动力学的新的实验装置的设计。该装置可以产生与火山柱相适应的具有可变颗粒浓度的持续下落颗粒柱。可控的实验参数包括颗粒大小分布、类型和释放速率。激光照明的微距摄影系统可以对飞行中的颗粒及其相互作用进行成像。落地颗粒的质量被记录下来，以告知沉积速率。定量测量包括颗粒形态表征、沉降速度、流速和浓度估计。通过对大范围参数的直接控制，同时观测颗粒相互作用过程和沉降动力学，将改进我们对火山羽流动力学的参数化。虽然该装置是专门为火山学调查而设计的，但它也可以用来探索环境和工业环境中自由落体颗粒柱的特征。(C)2022年作者(S)。
Volcanic plumes pose a hazard to health and society and a particular risk for aviation. Hazard mitigation relies on forecasting plume dispersion within the atmosphere over time. The accuracy of forecasts depends on our understanding of particle dispersion and sedimentation processes, as well as on the accuracy of model input parameters, such as the initial particle size distribution and concentrations of volcanic particles (i.e., volcanic ash) in the atmosphere. However, our understating of these processes and the accurate quantification of input parameters remain the main sources of uncertainty in plume dispersion modeling. It is usually impractical to sample volcanic plumes directly, but particle sedimentation can be constrained in the laboratory. Here, we describe the design of a new experimental apparatus for investigating the dynamics of free-falling volcanic particles. The apparatus can produce a sustained column of falling particles with variable particle concentrations appropriate to a volcanic plume. Controllable experimental parameters include particle size distributions, types, and release rates. A laser-illuminated macrophotography system allows imaging of in-flight particles and their interactions. The mass of landing particles is logged to inform deposition rates. Quantitative measurements include particle morphology characterization, settling velocities, flow rates, and estimation of concentrations. Simultaneous observations of particle interaction processes and settling dynamics through direct control over a wide range of parameters will improve our parameterization of volcanic plume dynamics. Although the apparatus has been specifically designed for volcanological investigations, it can also be used to explore the characteristics of free-falling particle columns occurring in both environmental and industrial settings. (C) 2022 Author(s).