Volcanic ash in jet engines: bouncing, sticking, and spreading of molten glass droplets

吸入喷气发动机的火山灰迅速融化，形成粘稠的硅酸盐液体液滴，可能会以高速撞击发动机表面。液滴可能反弹，或粘附和扩散，这取决于颗粒流变学、冲击速度、冲击角度和涡轮机表面的材料性质。液滴的粘附是有问题的，因为它会阻塞涡轮机叶片内的冷却管道，导致灾难性的发动机故障。该项目将使用实验室实验和理论分析来研究熔融玻璃液滴在热表面上反弹、粘附和扩散的条件。实验将使用高温熔融硅酸盐玻璃和环境温度模拟材料。该研究将借鉴工业相关液滴（例如喷涂，喷墨打印）的广泛文献，并将其扩展到与喷气发动机内部相关的制度。该项目将产生的对液滴行为的新的定量理解将支持项目合作伙伴罗尔斯·罗伊斯的工作，以确定大气灰负荷和灰特性（形状，成分，尺寸分布）的临界条件，在这些条件下，空域可以保持开放。

Volcanic ash that is ingested into jet engines melts rapidly to form droplets of viscous silicate liquid, which may impact engine surfaces at high speed. Droplets may bounce, or stick and spread, depending on particle rheology, impact velocity, impact angle, and the material properties of the turbine surfaces. Sticking of droplets is problematic because it can block the cooling ducts within turbine blades, leading to catastrophic engine failure. This project will use laboratory experiments and theoretical analysis to investigate the conditions under which molten glass droplets bounce off, stick to, and spread across hot surfaces. Experiments will use both high temperature molten silicate glasses and ambient temperature analogue materials. The study will draw on the extensive literature on industrially-relevant droplets (e.g. spray coating, inkjet printing) and extend it to regimes relevant to jet engine interiors. The new, quantitative understanding of droplet behaviour that this project will produce will support work by project partner Rolls-Royce to determine critical conditions of atmospheric ash loading and ash characteristics (shape, composition, size distribution) beneath which airspace can remain open.