Numerical Simulation and Advanced Modelling of Hydrogen-Fuelled Propulsion Systems for Reusable Launch Vehicles
Lead Research Organisation:
Newcastle University
Department Name: Sch of Engineering
Abstract
1 Overview
Reaction 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 Methodology
A 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
Reaction 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 Methodology
A 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
People |
ORCID iD |
| Andrew Aspden (Primary Supervisor) | |
| Thomas Howarth (Student) |
Publications
Howarth T
(2023)
Thermodiffusively-unstable lean premixed hydrogen flames: Phenomenology, empirical modelling, and thermal leading points
in Combustion and Flame
Howarth T
(2022)
An empirical characteristic scaling model for freely-propagating lean premixed hydrogen flames
in Combustion and Flame
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/R51309X/1 | 30/09/2018 | 29/09/2023 | |||
| 2282954 | Studentship | EP/R51309X/1 | 30/09/2019 | 29/09/2023 | Thomas Howarth |
| Description | - An empirical model was developed from a simplified configuration that allows prediction of appropriate flame speeds in laminar premixed hydrogen flames that accounts for the thermodiffusive response at lean conditions. - This model was then extended to allow for flame speed predictions in turbulent premixed hydrogen flames, accounting for both thermodiffusive and turbulence effects. - In addition to the two models developed, fundamental physics was explored in these kinds of flames, and phenomenological and theoretical explanations were given to explain model choices. - An example industrial micromix combustor was also simulated, where the underlying structure and stabilisation mechanism of the flame was explained; specifically, shear-driven mixing of recirculated products results in flame stabilisation by ignition events. |
| Exploitation Route | - The empirical models developed will help to characterise freely-propagating and turbulent thermodiffusively-unstable lean premixed hydrogen flames more appropriately, and improve turbulent flame speed predictions in device-scale simulations. - The flame speed models developed during this project can be used by industry to tune and improve their numerical solvers to predict the behaviour of their hydrogen-based combustion systems more accurately. - Based on the understanding of the industrial micromix combustor simulation, combustion engineers can both choose more appropriate combustion models, and create designs which utilise the various features of the flame to improve stability and operability ranges. |
| Sectors | Aerospace Defence and Marine Energy Transport |
| Description | This project has communicated with engine simulation engineers, combustion experts and academics addressing the primary sources of uncertainty in hydrogen combustion simulations as well as potential modelling solutions that could be implemented to reduce the sources of inaccuracy. In particular, software partners of the group have published work demonstrating the usage of models developed here to improve predictions for hydrogen IC engines. |
| First Year Of Impact | 2023 |
| Sector | Aerospace, Defence and Marine,Digital/Communication/Information Technologies (including Software) |
| Description | Industrial CASE partnership |
| Organisation | Reaction Engines |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | Developing fundamental understanding of thermodiffusive instabilities in lean premixed hydrogen combustion under a large range of physical conditions. Also provided an understanding of the structure and stabilisation mechanism in the micromix combustor used by Reaction Engines. |
| Collaborator Contribution | Raising awareness of the applicability of the undergoing work to industrial applications, providing conditions and design specifications that can be used for numerical configurations. |
| Impact | Publication of papers, also recorded for the project, DOIs: 10.1016/j.combustflame.2021.111805 10.1016/j.combustflame.2023.112811 10.48550/arXiv.2309.04815 |
| Start Year | 2019 |