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4785 |
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Wednesday, May 11, 2016, Yellow River Hall 2:20 PM Aviation Industry II |
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Viscous wetting of volcanic ash relevant to jet engine interaction |
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Wenjia Song* / Munich university, Germany Yan Lavallée/ University of Liverpool, Britain Kai-Uwe Hess/ Ludwig-Maximilians-Universität (LMU) , Germany Ulrich Kueppers/ Ludwig-Maximilians-Universität (LMU) , Germany Corrado Cimarelli/ Ludwig-Maximilians-Universität (LMU) , Germany Donald Bruce Dingwell/ Ludwig-Maximilians-Universität (LMU) , Germany |
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The ingestion of foreign particles (sand from desert storms, incinerated residues lofted into clouds, volcanic ash erupted at volcanoes) into jet engines is widely recognized as a potentially fatal hazard for aircraft operation. Historically, about 100 jet aircraft have inadvertently went through such ash clouds, endangering the lives of tens of thousands of passengers and causing millions of dollars worth of engine damage (such as the recent explosive eruption of Eyjafjallajökull volcano in Iceland). The nature of damage to jet engines is, when these foreign particles are ingested into jet engines, whose interiors (e.g., the combustor and turbine blades) reach 1200-2000 °C, they can abrade, melt, and stick to the internal components of the engine, clogging ventilation traps of the cooling system as well as imparting substantial damage and potentially resulting in catastrophic system failure. While much attention has been given to the influence of ash particle on thermo- and physical- properties of thermal barrier coatings attacked by molten ash, little quantitative work has been carried out on investigation of ash itself melting process under the jet engine conditions. Here, we experimentally develop the first quantitative model to predict melting and sticking conditions for the compositional range of volcanic ash encountered worldwide. The assumption that volcanic ash can be approximated by sand or dust is wholly inadequate, leading to an overestimation of sticking temperature and a correspondingly severe underestimation of the thermal hazard. Our findings confirm that the melting/softening behavior of volcanic ash at high temperatures is essentially controlled by the composition of erupted ash - which may serve as an accurate proxy of the thermal hazard potential of volcanic ash interaction with jet engines. The criterion proposed here successfully parameterizes the potentially complex melting process of volcanic ash and can be used to assess the deposition probability of volcanic ash upon ingestion into hot jet engines. |