Towards a multi-physics numerical strategy dedicated to the prediction of rotor/stator interactions within modern turbomachines

减少CO2排放的环境法规的演变与坚韧的经济背景相结合，是理解航空发动机最近设计演变的关键因素。在竞争激烈的市场中，发动机制造商必须开发更高效的发动机，通常考虑两种策略：（1）使用更轻的材料;（2）减少旋转和静态部件之间的间隙。作为提高效率的对应物，间隙的减小在发动机部件之间产生更频繁的结构接触，这可能引发危险的相互作用现象。因此，预测和减轻这些相互作用的能力已成为发动机制造商的当务之急。用于分析这种相互作用的全尺寸实验装置的非常高的成本促使开发专用的预测数值方法。然而，物理现象的复杂性使其不可能使用商业软件。在这种情况下，拟议的研究项目的目的是开发一个多物理方法的转子/定子相互作用的模拟，预测在发动机规模的相互作用现象的能力。它侧重于几个可能取得决定性突破的主题。首先，对压缩机和涡轮机等具有制造缺陷并包括潜在接触界面的完整发动机部件进行真实建模是进行有效数值模拟的先决条件。第二，它被建议来模拟转子/定子的相互作用占热和空气动力学效应。事实上，虽然在实验装置上已经目睹了显着的温度升高，但结构相互作用现象与热效应的耦合分析还有待完成。最后，建议建立设计准则，以创建叶片组件强大的相互作用源于结构接触。目前工业中常用的设计准则依赖于经验线性考虑，无法预测非线性相互作用。因此，与结构接触的部件振动响应相关的新标准的定义是一个基本问题，远远超出了航空航天工业的范围。总的来说，拟议的研究项目旨在从根本上了解对飞机发动机具有潜在破坏性的相互作用现象，以确保乘客的安全飞行，同时减少对环境的影响。

The evolution of environmental regulations for the reduction of CO2 emissions combined with a tough economic context are key factors for understanding recent design evolutions of aircraft engines. In a very competitive market, engine manufacturers must develop more efficient engines and two strategies are usually considered: (1) the use of lighter materials and (2) the reduction of clearances between rotating and static components. As a counterpart of an improved efficiency, the reduction of clearances yields more frequent structural contacts between the engine components which may initiate hazardous interaction phenomena. The ability to predict and mitigate these interactions has thus become imperative for engine manufacturers. The very high cost of full-scale experimental set-ups for analyzing such interactions motivates the development of dedicated predictive numerical methods. However, the complexity of the physical phenomena at play makes it impossible to use commercial softwares. In this context, the proposed research project aims at developing a multi-physics approach for the simulation of rotor/stator interactions, with the ability to predict interaction phenomena at the engine scale. It focuses on a few topics for which decisive breakthrough may be achieved. First of all, the realistic modeling of full engine components such as a compressor and a turbine featuring their manufacturing imperfections and including potential contact interfaces is a prerequisite for carrying out efficient numerical simulations. Second, it is proposed to simulate rotor/stator interactions accounting for thermal and aerodynamic effects. In fact, while significant temperature increase has been witnessed on experimental set-ups, the coupled analysis of structural interaction phenomena with thermal effects is yet to be done. Finally, it is proposed to establish design guidelines in order to create bladed components robust with respect to interactions stemming from structural contacts. Current design guidelines commonly used in the industry rely on empirical linear considerations that fail to predict non-linear interactions. The definition of new criteria related to the component vibratory response to structural contacts is thus a fundamental issue and goes way beyond the scope of the aerospace industry. Taken all together, the proposed research project aims at gaining a fundamental understanding of interaction phenomena that are potentially destructive for an aircraft engine, in order to ensure a safe flight for passengers while reducing their environmental impact.