Modelling of ice crystal icing in engines

[1]涡扇发动机劣化预测的数学和计算模型的开发在航空航天工业中具有重要意义。最近，汽车业注意到冰晶结冰(ICI)很可能是许多观察到的断电和发动机损坏的原因。在这种情况下，存在于高海拔的冰晶进入热引擎核心。尽管堆芯温度很高，但晶体可以部分熔化的状态附着在内部表面，然后向外脱落，损坏关键部件并造成电力损失。现有的关于冰晶形成和脱落机制的知识极其有限；最近的实验工作是为了更好地理解初始冰晶撞击，但还没有发展出准确的数学和计算模型。尤其是，后两份报告突出表明迫切需要更好地了解ICI的基本物理学。这个博士项目的重点将是开发数学模型来分析热发动机核心中的冰晶形成。[2]具体地说，我们的目标是制定包含过程基本物理的低维离散或连续模型。这些模型将需要描述初始撞击、附着和吸积以及分离的过程。我们将对这些模型进行研究，以求出吸积率、熔融率和分离阈值等关键量的标度律。我们还将为他们的研究开发理论(渐近)和计算方法。一旦建立和研究了基本模型，PHD将考虑重要的扩展，其中可能包括以下一些：(I)包括附加物理(例如可变的流场和热传输条件、不同的冰晶密度)和复杂的曲线几何形状的概括；(Ii)与最近的实验结果和数据进行验证；(Iii)反问题的调查(例如给定发动机诊断，是否可以确定飞行条件？

[1] The development of mathematical and computational models for the prediction of Turbofan engine deterioration is of great importance in the aerospace industry. Recently, the industry has noted that ice crystal icing (ICI) is likely responsible for numerous observed instances of power loss and engine damage. In this scenario, ice crystals present at high altitudes enter the hot engine core. Despite the high temperatures in the core, the crystals can accrete on the interior surfaces in a partially melted state, and then shed outwards, damaging key components and causing a power loss. Existing knowledge on the mechanism of ice crystal build-up and shedding is extremely limited; recent experimental work has been done to better understand the initial ice crystal impact, but accurate mathematical and computational models have not yet been developed. In particular, these latter reports have highlighted the pressing need to develop better understanding of the fundamental physics of ICI. The focus of this PhD project will be to develop mathematical models for the analysis of ice-crystal formation in the hot engine core. [2] In particular, our aim is to formulate low-dimensional discrete or continuum models that contain the essential physics of the process. The models will need to describe the processes of initial impact, attachment and accretion; and separation. These models will be studied in order to derive scaling laws for key quantities such as the accretion rates, melting rates, and separation thresholds. We will also develop theoretical (asymptotic) and computational methods for their study. Once the fundamental models have been formulated and studied, the PhD will consider significant extensions that may include some of the following: (i) generalisations to incorporate additional physics (e.g. variable flow fields and heat transfer conditions, different ice crystal densities) and complex curved geometries; (ii) verification against recent experimental results and data; (iii) the investigation of inverse problems (e.g. given engine diagnostics, can the flight conditions be determined?.