Erosional jets, the ultimate challenge in coupled flow-particle dynamics: Application to industrial post operational clean out

冲击射流广泛应用于各种工艺工程应用中，如隧道施工、喷漆和空蚀钻孔。在自然环境研究中，液体射流也被用作估计沉积物强度的方法。它们在核废料工业中对于放射性废料的混合也是非常重要的，因为它们由于缺少运动部件而优于机械叶轮。尽管多相射流混合系统具有广泛的相关性，但缺乏对其流动剖面、湍流和沉积床中再循环的定量研究，而目前对侵蚀阈值的预测也是经验性的。由于复杂的冲击轮廓，并且因为传统的激光或图像技术不能用于高固体负载，所以在表征中出现困难。作为一种替代方案，这个博士项目将寻求新的研究，以调查声学多普勒和后向散射仪器的应用，以确定这些复杂的流动和侵蚀剖面。测量结果将与射流的多相CFD模拟相结合，以专门预测用于移动核废料的冲击射流混合器，作为塞拉菲尔德有限公司操作后清理（POCO）操作的一部分。

Impinging jets are used in a wide range of process engineering applications, such as tunnelling operations, paint spraying and cavitation drilling. Liquid jets are also used as a method to estimate sediment strength in natural environment studies. They are additionally important within the nuclear waste industry for mixing of radioactive wastes, as they are preferred over mechanical impellers, due to the lack of moving parts. Despite this wide relevance of multiphase jet mixing systems, quantitative studies of their flow-profiles, turbulence and recirculation in sediment beds are lacking, while current predictions of erosion thresholds are also empirical. Difficulties arise in characterisation, due to the complex impingement profiles and because traditional laser or image techniques cannot be used at high solids loads. As an alternative, this PhD project will seek new research to investigate the application of acoustic Doppler and backscatter instruments to characterise these complex flows and their erosion profiles. Measurements will be coupled with multiphase CFD simulations of the jets, to specifically enable the prediction of impinging jet mixers used to mobilise nuclear wastes, as part of post operational clean out (POCO) operations at Sellafield Ltd.