Periodic Reporting for period 1 - HESTIA (HydrogEn combuSTion In Aero engines)
Période du rapport: 2022-09-01 au 2024-02-29
HESTIA (HydrogEn combuSTion In Aero engines) contributes to reach carbon neutrality in the aviation sector by 2050 in line with the EU Green Deal objectives. In fact, HESTIA focuses on the research into new propulsion systems and fuel sources and, considering that the H2 propulsion involves a climate impact reduction of 50-75% when compared to kerosene, it responds to the need to better understand key phenomena of burning H2 in aircraft engines. The overall objective of the HESTIA project is to increase scientific knowledge related to H2/air combustion in aircraft engines and its related influencing parameters. More specifically, the project will further the understanding of the H2/air combustion through elementary lab scale testing and basic modelling of specific phenomena, develop experimental capabilities and improved modelling methodologies for detailed assessment of H2/air characteristics in representative aeronautical conditions, and benchmark the performance of incremental and breakthrough injection systems concepts and identify the most relevant concepts. To achieve these objectives, HESTIA has a duration of 48 months and is composed of three scientific Work Packages, focusing on studying the fundamental physical processes involved in turbulent H2/air aeronautical combustors by conducting in parallel theoretical studies, high-fidelity experiments, and high-performance computations (WP1: Mastering key phenomena of H2/air combustion), developing incremental and breakthrough technologies for injection systems especially designed for the use of hydrogen in an aircraft (WP2: Injection systems design), and on consolidating knowledge from the two previous work packages and apply it to more representative engine environments (WP3: Specifications and operability assessments). The outputs produced thanks to HESTIA are TRL3 experimental databases for different flame configurations; advanced numerical tools for the prediction of thermo-acoustics instabilities; validated turbulent combustion models for CFD; validated models for NOx emissions, cooling effects, flame stability; advanced diagnostics methodologies in H2/air flames to evaluate H2 mixing, NOx levels measurements, flow fields, and thermal effectiveness; validated CFD methods and ‘best practice’ methodology for H2 combustion simulation in aero engines combustor configurations; cross-comparison of the different H2 injection concepts regarding some key specifications and selection of concepts that can provide a significant reduction of NOx emission (TRL2/3); a roadmap to mature H2 injection technology to TRL6 by 2028. To realize these outputs, and so to achieve its objectives, HESTIA can count on a consortium coordinated by Safran and composed of 5 European aero-engine manufacturers and 18 universities and research centres.
During the first reporting period (M1-M18), within the framework of WP1, several injection strategies have been developed to study different flame stabilisation mechanisms; dedicated test bench are currently being set to investigate specifically wall heat transfer; preliminary measurements of NOx at the exit of combustors for different power / mixture fraction have been implemented (D1.4). Moreover, flame dynamics have been experimentally studied on swirled hydrogen burner; development and validation of Lattice-Boltzmann method for prediction of thermo-acoustic instabilities in reactive flows have been implemented; a combined two stage computational strategy for computing flame instabilities has been developed. Finally, numerical simulations of hydrogen/air combustion are conducted in various geometries: bluff-body burner, jet in crossflow, swirl burner; ignition dynamics, stabilization (flame holding), and possible flashback scenarios are currently studied in the bluff-body burner geometry; several modelling strategies are being developed to represent hydrogen/air combustion with special emphasis placed on Lewis number effects, heat transfer, and NOx formation.
Within the framework of WP2, a burner geometry which uses a jet in crossflow injection scheme has been designed. Three different injectors with the same injection properties have been manufactured, each featuring an upstream shift of the injection orifices creating different premixed levels of hydrogen and air. Extensive measurement data already has been collected for one of the configurations under different operation conditions. Moreover, the simulation of the first configuration for the only slightly premixed level of hydrogen and air has started. Furthermore, CFD work has been done on the development of hydrogen fuel injector for an RQL combustion system. Three types of injection concepts, co-axial jet, planar jet and jet-in-cross flow have been defined and their CFD assessment was carried out. The findings from CFD and WP3 fundamental studies were reviewed and it ultimately led to the selection of a direct injection multipoint design for the first test campaign in Q2 2024.
Finally, the progress towards the WP3 objectives can be summarised in the realisation of the following significant results: atmospheric test rig designed and under manufacture & initial testing scheduled for Q2 2024; elevated pressure test rig concept complete, design for manufacture under way; on course to achieve low TRL test rig design objective; identified novel multipoint hydrogen injection concepts with relevance to aerospace applications from fundamental scaling analysis; theoretical development of a novel measurement technique for interrogation of hydrogen flames.
Within the framework of WP2, a burner geometry which uses a jet in crossflow injection scheme has been designed. Three different injectors with the same injection properties have been manufactured, each featuring an upstream shift of the injection orifices creating different premixed levels of hydrogen and air. Extensive measurement data already has been collected for one of the configurations under different operation conditions. Moreover, the simulation of the first configuration for the only slightly premixed level of hydrogen and air has started. Furthermore, CFD work has been done on the development of hydrogen fuel injector for an RQL combustion system. Three types of injection concepts, co-axial jet, planar jet and jet-in-cross flow have been defined and their CFD assessment was carried out. The findings from CFD and WP3 fundamental studies were reviewed and it ultimately led to the selection of a direct injection multipoint design for the first test campaign in Q2 2024.
Finally, the progress towards the WP3 objectives can be summarised in the realisation of the following significant results: atmospheric test rig designed and under manufacture & initial testing scheduled for Q2 2024; elevated pressure test rig concept complete, design for manufacture under way; on course to achieve low TRL test rig design objective; identified novel multipoint hydrogen injection concepts with relevance to aerospace applications from fundamental scaling analysis; theoretical development of a novel measurement technique for interrogation of hydrogen flames.
The multipoint injection concepts, although still at lab scale, are beyond the state-of-the-art kerosene injectors that are incorporated in products currently in service. The research is at early stages and further work in terms of experimental validation and refinement of the designs is required, as planned in HESTIA, to understand their potential benefits and risks for incorporation into future products. Moreover, the HESTIA WP3 has enabled scaling analysis which has directly led to early design rules for lean multi-point hydrogen injection concepts suitable for aerospace gas turbine applications. This has significantly reduced the design space and narrowed focus on test hardware. Generally, the development of H2 combustion systems for aero engines only started a few years ago. Therefore, a lot of further development, demonstration and validation has to be done. However, the first rig test results are very promising. However, apart from the combustion system development, a lot of development is required in the fuel supply systems, aircraft fuel tank and airport infrastructure.