Numerical Simulation and Advanced Modelling of Hydrogen-Fuelled Propulsion Systems for Reusable Launch Vehicles

1概述反应引擎有限公司(REL)是一家总部设在英国的公司，成立于1989年，为一种新型的高超声速推进系统--协同式吸气式火箭发动机(SABRE)设计和开发技术。雷尔的突破性技术是一种超轻型热交换器，通过防止发动机部件过热，使军刀发动机能够在非常规的高速下使用传统的空气技术。军刀技术将使飞机在大气层中的飞行速度超过音速的五倍，并实现单级到轨道的太空运载火箭，从而降低成本并改善进入太空的机会。军刀发动机成功的关键是使用氢作为燃料，在远未被很好理解的非常规条件下燃烧。在这些条件下的燃烧包括固有的不稳定性(热扩散、流体动力和热声)，这给燃烧室设计带来了巨大的挑战。这种世界领先的技术的原型制作成本极其昂贵，而数值模拟可以提供无与伦比的洞察力，了解这种新型燃烧器所涉及的基本物理过程，从而帮助设计和开发过程。然而，现有的数值模拟已经证明了对用于描述湍流混合和火焰物理的模型的敏感性；需要高分辨率的数值模拟来开发和验证可用于燃烧室设计和开发的可靠的湍流燃烧模型。2方法将建立一个高保真三维直接数值模拟数据库，该数据库既考虑了氢燃料直接喷射到亚音速横流中的湍流混合，也考虑了随后在与SABRE相关的条件下的下游稀薄燃烧。NASA的低排放贫氢燃烧器将被用作目标测试案例，反应发动机将提供更多可用于初始化的必要条件。域名计算将使用PeleLM(如果必要，还将使用PeleC)进行，该计算由加州劳伦斯·伯克利国家实验室开发，并建立在PI具有超过14年经验的框架上。主要优点包括利用低马赫数近似和自适应网格重新划分，这两者都显著减少了计算成本，并针对大规模并行超级计算机进行了优化，使其成为世界领先的湍流燃烧计算工具。规模越来越大的模拟将分阶段进行，从一个高规格的工作站开始，通过NU HPC设施“Rocket”，直到国家超级计算机“Archer”。将详细分析DNS数据，以评估用于雷诺平均纳维斯托克斯(RANS)和大涡模拟(LES)方法的现有湍流火焰模型，并指导适当的新模型的开发。这些模型将在工程CFD软件框架中进行实施和测试，并在与进行DNS模拟相同的情况下进行验证；这将允许进行直接比较和迭代模型开发，从而在方法中建立信任，从而可以更广泛地应用于军刀燃烧室技术的设计和开发。建议的研究领域：连续介质力学、燃烧工程、流体动力学和空气动力学、数值分析、氢气和替代能源矢量

1 OverviewReaction Engines Ltd (REL) is a UK-based company formed in 1989 to design and develop technologies for a new class of hypersonic propulsion system - the Synergetic Air-Breathing Rocket Engine (SABRE). REL's breakthrough technology is an ultra-lightweight heat exchanger that enables the SABRE engine to use conventional aerotechnology at unconventionally high speeds by preventing engine components overheating. SABRE technology will enable aircraft to fly over five times the speed of sound in the atmosphere, and realise single-stage-to-orbit space launch vehicles, reducing costs and improving access to space.Key to the success of the SABRE engine is using hydrogen as fuel, burning under unconventional conditions that are far from well-understood. Combustion at these conditions includes inherent instabilities (thermodiffusive, hydrodynamic and thermoacoustic) that pose signicant challenges to combustor design. Prototyping such world-leading technology is extremely expensive, and numerical simulation can provide unparalleled insight into the fundamental physical processes involved in such novel combustors, thereby aiding the design and development process. However, existing numerical simulations have demonstrated a sensitivity to models used to describe turbulent mixing and flame physics; there is a need for high-resolution numerical simulations to develop and validate reliable turbulent combustion models that can be used for combustor design and development.2 MethodologyA database of high-fidelity three-dimensional Direct Numerical Simulations (DNS) will be constructed that consider both the turbulent mixing of direct injection of hydrogen fuel into a sub-sonic cross-flow, and the subsequent downstream lean combustion at conditions relevant for SABRE. NASA's low-emission lean-hydrogen burner will be used as a target test cases, and Reaction Engines will provide further necessary conditions that can be used for initialisation.The DNS calculations will be carried out using PeleLM (and PeleC, if necessary), developed at the Lawrence Berkeley National Laboratory in California, and built on a framework with which the PI has over fteen years' experience. Key advantages include exploitation of the low Mach number approximation and adaptive mesh renement, both of which signicantly reduce computational expense, and is optimised for use on massively-parallel supercomputers, making it a world-leading computational tool for turbulent combustion. Simulations increasing in size will be carried out in stages, starting from a high-specication workstation, through the NU HPC facility "Rocket", up to the national supercomputer "Archer".The DNS data will be analysed in detail to assess existing turbulent flame models used for Reynolds Averaged Navier Stokes (RANS) and Large Eddy Simulation (LES) approaches, and to guide development of new models as appropriate. The models will be implemented and tested in an engineering CFD software framework, and validated on the same cases as conducted for the DNS simulations; this will allow direct comparisons to be made and to iterate on the model development, thereby establishing the condence in the approach so that it can be applied more generally to aid the design and development of SABRE combustor technology.Suggested research areas: Continuum Mechanics, Combustion Engineering, Fluid Dynamics and aerodynamics, Numerical Analysis, Hydrogen and alternative energy vectors