Experimental interaction of magma and "dirty" coolants
Experimental interaction of magma and "dirty" coolants
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DOI：
10.1016/j.epsl.2011.01.010
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发表时间：
2011-03-01
影响因子：
5.3
通讯作者：
Schmid, Andrea
中科院分区：
文献类型：
--
作者：
Schipper, C. Ian;White, James D. L.;Schmid, Andrea
火山喷口中水的存在可能对碎裂和喷发动力学产生巨大影响，但人们对外部水中颗粒物的存在将如何进一步改变喷发知之甚少。火山大厦本质上是“肮脏”的地方，在那里有多种来源的颗粒物质和颗粒物质。我们提出的实验结果，旨在模拟熔融玄武岩和各种“冷却剂”之间的非爆炸性相互作用，范围从膨胀;悬浮液0至30质量%的膨润土粘土在纯水中，异质和/或分层悬浮液，包括膨润土，砂，合成玻璃珠和/或自然分选浮石。四种类型的数据被用来验证相互作用：（1）视觉/视频观察;（2）所产生的颗粒的粒度和形态;（3）来自八个热电偶网络的传热数据;以及（4）来自三个力传感器的声学数据。在具有类似于20%沉积物的均质冷却剂中，热传递是通过强制对流和传导进行的，并且热粒化效率较低，导致较少的块状颗粒、较大的颗粒和较弱的声学信号。许多粒子是液滴状或/和“泡状”，含有充满冷却剂的气泡。这两种颗粒类型表明显着的流体动力岩浆冷却剂混合，其中许多重新焊接成复合颗粒。向非均质悬浮液中添加粗材料进一步减慢热传递，从而减少热造粒，并且大颗粒的可变互锁防止有效的流体动力学混合。这主要导致重新焊接的熔体堆以及熔体和热量在整个冷却剂体积中的低效分布。我们的研究结果表明，即使在水中的沉积物浓度适中，将显着限制非爆炸性岩浆-水相互作用过程中的热传递。在高浓度下，冷却效率的显着降低和混合的增加有助于解释球状熔尘，并提供相关的信息，分析与高爆炸性的熔融燃料-冷却剂在碎片填充的火山口的相互作用的预混合。(C)2011 Elsevier B. V.保留所有权利。
The presence of water at volcanic vents can have dramatic effects on fragmentation and eruption dynamics, but little is known about how the presence of particulate matter in external water will further alter eruptions. Volcanic edifices are inherently "dirty" places, where particulate matter of multiple origins and grainsizes typically abounds. We present the results of experiments designed to simulate non-explosive interactions between molten basalt and various "coolants," ranging from homogeneou; suspensions of 0 to 30 mass% bentonite clay in pure water, to heterogeneous and/or stratified suspensions including bentonite, sand, synthetic glass beads and/or naturally-sorted pumice. Four types of data are used to characterise the interactions: (1) visual/video observations; (2) grainsize and morphology of resulting particles; (3) heat-transfer data from a network of eight thermocouples; and (4) acoustic data from three force sensors. In homogeneous coolants with similar to 20% sediment, heat transfer is by forced convection and conduction, and thermal granulation is less efficient, resulting in fewer blocky particles, larger grainsizes, and weaker acoustic signals. Many particles are droplet-shaped or/and "vesicular," containing bubbles filled with coolant. Both of these particle types indicate significant hydrodynamic magma-coolant mingling, and many of them are rewelded into compound particles. The addition of coarse material to heterogeneous suspensions further slows heat transfer thus reducing thermal granulation, and variable interlocking of large particles prevents efficient hydrodynamic mingling. This results primarily in rewelded melt piles and inefficient distribution of melt and heat throughout the coolant volume. Our results indicate that even modest concentrations of sediment in water will significantly limit heat transfer during non-explosive magma-water interactions. At high concentrations, the dramatic reduction in cooling efficiency and increase in mingling help to explain globular peperite, and provide information relevant to analyses of premixing associated with highly-explosive molten fuel-coolant interactions in debris-filled volcanic vents. (C) 2011 Elsevier B.V. All rights reserved.