Development and Application of a Simulation-Based Design Process for Fuel-Flexible Burners using Additive Manufacturing

为了向未来可持续能源系统转型，迫切需要燃料灵活的燃烧器来科普从天然气到全氢燃料操作的逐步过渡。在火焰稳定性和逆燃、排放和混合物形成领域，对于这种燃烧器的开发存在重大挑战，因为与常规燃料相比，氢基燃料具有根本不同的燃烧特性。该提案的最终目标是使工业燃烧器系统的设计能够特别强调不同氢气/甲烷混合物的稳健和有效操作，同时确保可制造性和安全性。在拟议的工作中，这些挑战将通过将模型开发和基于仿真的设计过程与实验研究和创新的增材制造（AM）相结合来解决。后者允许在设计上有很大的自由度，以创建紧凑、灵活和内在稳定的燃烧器。在该项目中，将开发一种逆向设计过程，并作为示范，应用于优化工业多喷口燃烧器的特定目标量，包括火焰特性，如稳定性（火焰回火和吹出）和排放（NOx，CO），以及设计参数，如内部压力损失和耐热性。一个挑战是需要准确和具有成本效益的氢基燃料模拟技术，这将作为该项目的一部分开发。这包括雷诺平均纳维尔-斯托克斯（RANS）模拟，将利用大涡模拟结果和实验数据，通过采用基于Enclusive卡尔曼滤波器的数据同化，提高RANS模拟的预测性。实验提供了湍流火焰的消耗速度和属性，包括RANS模型中的热扩散不稳定性的影响。同化RANS模型，然后将应用于优化燃烧器的几何形状和操作策略，同时考虑AM施加的设计约束，使用伴随灵敏度。设计过程将通过AM使用燃烧器的参数模型来促进。进一步的发展将提高AM制造的燃烧器的质量，包括优化薄壁，细丝特征和可实现的悬垂角，特别是耐高温材料。本提案中包括燃烧工程和AM在内的强跨学科方法将为燃料灵活的工业燃烧器的基于模拟的设计过程提供方法框架。

For the transformation towards future sustainable energy systems, fuel-flexible burners are urgently needed to cope with the gradual transition from natural gas to fully hydrogen-fueled operation. Significant challenges exist for the development of such burners in the areas of flame stability and flashback, emissions, and mixture formation, as hydrogen-based fuels have fundamentally different combustion properties compared to conventional fuels. The ultimate objective of this proposal is to enable the design of industrial burner systems with special emphasis on robust and efficient operation with different hydrogen/methane blends while ensuring manufacturability and safety. In the proposed work, these challenges will be tackled by combining model development and a simulation-based design process with experimental investigations and innovative additive manufacturing (AM). The latter allows for a large degree of freedom in design needed to create compact, flexible, and intrinsically stable burners. In this project, an inverse design process will be developed and, as a demonstration, applied to optimize an industrial multi-jet burner with respect to specific target quantities including flame properties, such as stability (flame flashback and blow-off) and emissions (NOx, CO), as well as design parameters, such as internal pressure loss and heat resistance. One challenge is the need for accurate and cost-efficient simulation techniques for hydrogen-based fuels, which will be developed as part of the project. This comprises Reynolds-averaged Navier Stokes (RANS) simulations, which will be improved in predictiveness by applying data assimilation based on the Ensemble Kalman Filter using results from large-eddy simulations and experimental data. The experiment provides consumption speeds and properties of turbulent flames necessary to include effects of thermodiffusive instabilities in the RANS model. The assimilated RANS model will then be applied to optimize the burner geometry and operating strategies using adjoint sensitivities while considering design constraints imposed by AM. The design process will be facilitated by AM using parametric models of the burner. Further developments will be made to improve the quality of AM-fabricated burners, which includes optimizations regarding thin walls, filigree features, and achievable overhang angles especially for high-temperature resistant materials. The strongly interdisciplinary approach including combustion engineering and AM in this proposal will enable the methodological framework for a simulation-based design process of fuel-flexible industrial burners.