Multi-objective Optimization of Patterned Void Structures

燃气轮机热区部件具有很高的工作温度和严重的温度梯度。结果，发动机部件内部产生了高应力和应变，从而限制了它们的寿命和可靠性，并增加了发动机维修和大修成本。冷却空气通常用于降低部件温度和热应力。虽然有效，但这一策略减少了可用于燃烧的空气量，导致了NOx和CO排放更高的不完全燃烧。在最近结束的与劳斯莱斯的Engage项目中，我们得出的结论是，可以将空隙设计成最佳形状，以减少热部件中的应力和应变，从而延长发动机寿命。虽然减少应力至关重要，但其他方面，如冷却和减震，控制发动机的性能。作为Engage的自然延伸，该项目专注于寻找能够同时协调燃气轮机的以下性能指标的最佳空隙模式：结构完整性、冷却和阻尼，并对制造过程中出现的变化保持稳健。据我们所知，这是一部新奇的作品，也是此类作品中的第一部。它需要使用空气流动和应力的分析工具，能够有效处理多个目标的结构(尺寸、形状和拓扑)优化问题的公式和解决方案，以及结果的实验验证，每一项都有助于解决燃气轮机发动机中实现最佳单元模式的问题。该项目的成功结果将使劳斯莱斯加拿大公司能够设计出可靠性更高的发动机，同时实现更高的效率和更低的排放。此外，该项目将在结构力学、拓扑学和图案化孔洞结构和多孔材料的多目标优化领域产生宝贵的研究见解(包括基础和应用)，以及培训精通燃气轮机技术的高素质工程师。

Hot section components of gas turbine engines experience very high operating temperatures and severe thermal gradients. As a result, high stresses and strains develop within engine components, thereby limiting their life and reliability, as well as increasing engine repair and overhaul costs. Cooling air is generally used to reduce component temperature and thermal stresses. While effective, this strategy reduces the amount of air available for combustion, leading to incomplete combustion with higher NOx and CO emissions. In a recently concluded Engage project with Rolls-Royce, we reached to the conclusion that voids can be patterned in optimal shapes to reduce stress and strain in hot-section components, thereby increasing engine life. Whereas stress reduction is crucial, other aspects, such as cooling and damping, govern engine performance. As a natural extension of the Engage, this project focuses on the search of optimal void patterns that can reconcile concurrently the following performance metrics of the gas turbine: structural integrity, cooling, and damping, and be robust to variations emerging from the manufacturing process. To our knowledge, this work is novel and the first of this kind. It requires the use of analysis tools for air flow and stress, the formulation and solution of structural (size, shape and topology) optimization problems that can effectively handle multiple objectives, and the experimental validation of the results, each contributing to address the implementation of optimal cellular patterns in gas turbine engines. A successful outcome from this project will allow Rolls-Royce Canada to design engines with increased reliability while achieving increased efficiency and lower emissions. Furthermore the project will yield invaluable research insights (both fundamental and applied) in the fields of structural mechanics, topology and multi-objective optimization of patterned void structures and cellular materials at large, along with the training of highly qualified engineers, proficient in gas turbine technologies.