Periodic Reporting for period 2 - HESTIA (HydrogEn combuSTion In Aero engines)
Okres sprawozdawczy: 2024-03-01 do 2025-08-31
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 improve the understanding of the H2/air combustion through concurrent work streams: elementary lab scale testing, modelling of specific physical phenomena, development of experimental capabilities and improved modelling methodologies for detailed assessment of H2/air characteristics in representative aeronautical conditions, and benchmarking of performance of incremental and breakthrough injection systems concepts to identify the most relevant ones. To achieve these objectives, HESTIA has a duration of 48 months and is composed of 3 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 deliver 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.
Within WP1, the first reporting period (M1-M18) focused on developing several hydrogen injection strategies and establishing numerical tools to predict thermo-acoustic instabilities and hydrogen/air combustion behaviour. During the second period (M19–M36), a new in-situ diagnostic tool for NOx measurement was developed, and experimental campaigns provided deeper insight into turbulent flame dynamics and cooling effects. Low-order and advanced turbulent combustion models were established to predict thermo-diffusive instabilities, flame behaviour, and NOx emissions.
Within WP2, the initial activities led to the design and testing of a jet-in-crossflow burner and injector variants with different premixing levels, while CFD studies supported concept selection for hydrogen combustion systems. During the second period, LUH characterised flame stabilisation regimes, and MTU validated CFD results against LUH experiments. AVIO and partners completed design-space exploration with 2D/3D CFD and initiated hardware manufacturing. INSA’s strut injectors demonstrated excellent operability and low-NO performance at high pressure, and RRUK advanced multipoint direct-injection concepts, assessing manufacturability and selecting three configurations for further testing.
Within WP3, the first period delivered the design of atmospheric and elevated-pressure test rigs and identified novel multipoint hydrogen injection concepts through scaling analysis. During the second period, Safran developed and validated a CFD strategy for RQL and strut injectors, while MTU modelled hydrogen combustion and thermal behaviour using conjugate heat transfer. GEDE supported TUM in establishing a modular test rig with integrated H2 infrastructure. LBORO–RRUK designed and tested multipoint direct-hydrogen-injection (DHI) concepts, assessing NOx, operability, and flame structure, while RRD–DLR developed a retrofit H2 injector for altitude-representative testing.
Within WP2, the initial activities led to the design and testing of a jet-in-crossflow burner and injector variants with different premixing levels, while CFD studies supported concept selection for hydrogen combustion systems. During the second period, LUH characterised flame stabilisation regimes, and MTU validated CFD results against LUH experiments. AVIO and partners completed design-space exploration with 2D/3D CFD and initiated hardware manufacturing. INSA’s strut injectors demonstrated excellent operability and low-NO performance at high pressure, and RRUK advanced multipoint direct-injection concepts, assessing manufacturability and selecting three configurations for further testing.
Within WP3, the first period delivered the design of atmospheric and elevated-pressure test rigs and identified novel multipoint hydrogen injection concepts through scaling analysis. During the second period, Safran developed and validated a CFD strategy for RQL and strut injectors, while MTU modelled hydrogen combustion and thermal behaviour using conjugate heat transfer. GEDE supported TUM in establishing a modular test rig with integrated H2 infrastructure. LBORO–RRUK designed and tested multipoint direct-hydrogen-injection (DHI) concepts, assessing NOx, operability, and flame structure, while RRD–DLR developed a retrofit H2 injector for altitude-representative testing.
The multipoint injection concepts, although still at laboratory scale, already go beyond the state-of-the-art kerosene injectors currently in service. Within WP3, scaling analyses have produced early design rules for lean multi-point hydrogen injection suitable for aerospace gas turbines, reducing the design space and guiding test hardware development. The research remains at an early stage, with further experimental validation planned to assess benefits and risks for future product integration. Moreover, measurements in ST3.1.5 have improved understanding of novel DHI injector behaviour under representative conditions, informing injector design and future engine integration, while ST3.1.1 numerical work confirms the robustness of CFD methods in reproducing flame characteristics for different injection technologies.
WP2 activities are likewise beyond the current state of the art for hydrogen use in aeronautics. T2.2 is advancing research on strut and multi-point injectors: ST2.2.1 shows real potential for H2/air strut injectors in future combustors, while direct-injection concepts are novel compared to kerosene injectors in RRUK products, with benefits to be assessed through low-TRL testing at LBORO.
Finally, WP1 efforts on fundamental hydrogen combustion mechanisms and turbulent combustion model development supports the design of next-generation hydrogen combustion chambers.
Overall, hydrogen combustion system development for aero engines is still at an early stage, requiring extensive validation and parallel progress in fuel supply, aircraft tanks and airport infrastructure.
WP2 activities are likewise beyond the current state of the art for hydrogen use in aeronautics. T2.2 is advancing research on strut and multi-point injectors: ST2.2.1 shows real potential for H2/air strut injectors in future combustors, while direct-injection concepts are novel compared to kerosene injectors in RRUK products, with benefits to be assessed through low-TRL testing at LBORO.
Finally, WP1 efforts on fundamental hydrogen combustion mechanisms and turbulent combustion model development supports the design of next-generation hydrogen combustion chambers.
Overall, hydrogen combustion system development for aero engines is still at an early stage, requiring extensive validation and parallel progress in fuel supply, aircraft tanks and airport infrastructure.