Mobility and Transport: Powering Aviation

The "Flightpath 2050 - Europe's Vision for Aviation" report formulates the goal of significantly reducing CO2 and NOx emissions as well as noise emissions. With our research, we are making a contribution to the formulated goals. In particular, the switch from kerosene to hydrogen is intended to contribute to the decarbonization of engine emissions. 

Website: Research at SFM
Contact: Katharina Meinecke 

Reliability and Safety

Gas mixtures consisting of large amounts of hydrogen (H₂) and carbon monoxide (CO) are extensively used in chemical engineering processes, e. g. syngas from reforming or gasification. However, depending on the composition, the gas mixture exhibits a wide explosive range. Consequently, understanding and predicting the conditions for handling the mixture safely is of importance. Especially, the potential development of a H₂/CO mixture in severe accident scenarios of nuclear power plants is of great concern and requires research on a fundamental level.

Website: Research at SFM
Contact: Kajetan Planötscher

Life cycle assessment (LCA) of SAFs

The aviation industry's net-zero carbon emissions target (2050) is focused on delivering a maximum reduction in emissions. In this context, the SFM group is researching and developing technical and environmental analyses for sustainable aviation fuel (SAF) production. This research aims to determine the environmental analysis of SAF pathways considering the European-German scenario based on the 2050 ICAO-SAF Vision. We are working on the Aviation Demand Modelling SAF pathways (i.e., F-T and ATJ technologies) considering technological scenarios for 2030-2040-2050 in Germany, aiming to identify/quantify environmental impacts/supply chain hotspots based on a Life cycle assessment (LCA) approach.

Website: Research at SFM
Contact: Dr. Pablo Silva Ortiz

Chemical kinetic mechanisms for SAF

Detailed study on automated chemical kinetic mechanism generation and reduction for SAF surrogates

Due to the ever-more urgent problem of global warming, the aviation industry is looking towards using Sustainable Aviation Fuel (SAF). While using SAF leads to a reduction in CO₂ emissions, and might even result in net carbon neutrality, the problem of non-CO₂ emissions, like nitrogen oxides (NO_x) and soot, is not directly tackled.

The SAFMech project aims to investigate the chemical-physical processes involved in the combustion of Fischer-Tropsch (FT) and Alcohol to Jet (ATJ) type SAF surrogates, using innovative computational/numerical methods and making the advances usable for industrial application.

The work involves the generation of detailed chemical kinetic mechanisms for SAF surrogates using the Reaction Mechanism Generator (RMG) software, followed by the development of software for mechanism reduction and optimization while maintaining the accuracy of the detailed mechanism as best as possible. These reduced kinetic mechanisms, along with fluid dynamics models, are used to predict essential combustion characteristics. Furthermore, due to their role in soot nucleation and growth, the study also aims to provide a more detailed insight into the formation of polycyclic aromatic hydrocarbon (PAH).

 “SAFMech” contributes to the environmental protection objectives of “Flightpath 2050” with respect to its noise reduction and environmental compatibility objectives of aircraft engines.

Type: Bavarian aviation research program (BayLu25)
Funding: Bavarian State Ministry of Economic Affairs, Regional Development and Energy
Funding code: BayLu25 - BLU-2109-0028
Runtime: 01.07.2022 - 30.06.2025
Website: Powering Aviation - Professur für Sustainable Future Mobility
Contact: Pooja Neema, Michael Geuking 

H2 Combustion

Investigation of the physical phenomena related to the hydrogen-air combustion of future hydrogen-powered aircraft engines.

To reduce the climate impact of aviation, decarbonization is a major challenge. Current combustion chambers are burning hydrocarbon fuels, such as kerosene or, more recently, emerging SAF products. Hydrogen is also considered today as a promising energy carrier but burning hydrogen creates radically new challenges which need to be understood and anticipated.
HESTIA focuses on increasing the scientific knowledge of hydrogen-fuelled aero-engines. The related physical phenomena will be evaluated through fundamental experiments. This experimental work will be closely coupled to numerical activities by project partners who will adapt or develop models and progressively increase their maturity so that they can be integrated into industrial CFD codes.

Type: European Commission within the Horizon Europe Programme
Funding: European Commission: Climate, Energy and Mobility
Funding code: 101056865
Runtime: 01.09.2022 - 31.08.2026
Website: European Comission - HydrogEn combuSTion In Aero engines
Contact: Katharina Meinecke

H2 Combustion

Investigation and development of combustion processes with the lowest nitrogen oxide emissions ("Low NOx") for hydrogen in aircraft engines.

Compared to RQL combustion in hydrogen-fueled aero engines, the state of knowledge for technically premixed combustion with hydrogen in aircraft engines is still far behind. This applies to the conceptual level as well as to the optimization of promising concepts. However, the further development of premixed hydrogen combustion is expected to bring several benefits especially regarding the reduction of NOx emissions. This project therefore investigates the behavior of an innovative, premixed injection and combustion concept which is suitable for the use of hydrogen. Therefore, steady-state (mixture formation and heat release distribution) and transient (ignition, start-up and shutdown) behavior will be evaluated and thermoacoustic investigation of premixed combustion with lowest NOx emissions will be conducted. GE Aerospace will design the injection and combustion system and deliver them to TUM where the above-mentioned experiments will be performed.
In addition, a novel axially staged system will be developed at TUM and first functional tests will be performed. This system is intended to apply the developed technology for staged hydrogen combustion from stationary gas turbines to aircraft engines, thus paving the way for new approaches to emission reduction. The staged system has an increased reduction potential compared to the non-staged one. To meet the demands in various flight conditions and thus different load requirements, the stages are tailored to different operating points in various configurations. This concept is first designed through simulation and then experimentally tested, with measurements focusing on emissions.

Type: Collaborative project: H2-Low NOx Combustor & Conditioning for Start-up
Funding: Federal Ministry for Economic Affairs and Climate Action
Funding code: 20M2211D
Runtime: 01.11.2023 - 31.12.2026
Website: Powering Aviation - Professur für Sustainable Future Mobility
Contact: Adrian Hochmuth, Maximilian Aubel 

H2 Combustion

The project “Greener-RQL” supports the development of new hydrogen aircraft engines by focusing on the causes of the Growl/Rumble phenomenon.

The Growl/Rumble-phenomenon describes a low frequency noise, which can be perceived in the aircraft cabin as unpleasant and risks to damage the engines. Entropy and equivalence ratio waves are suspected as possible causes for this phenomenon. However, well-founded research is still lacking, especially in the context of hydrogen use.
To address this shortcoming “Greener-RQL“ investigates the convection of entropy waves and equivalence ratio waves as well as their feedback mechanism with acoustic waves inside an aero engine combustion chamber with air-staging (RQL).
RQL combustion chambers are a concept which traditionally reduce nitrogen oxide emissions. This type of chamber divides combustion into two stages. In the first stage, combustion occurs with excess fuel in the rich regime. While in the second stage, additional air is added and combustion occurs under excess air in the lean regime. This allows to evade combustion near the stochiometric regime, high temperatures, and associated nitrogen oxides production.
“Greener-RQL”, supported by the Bavarian aviation research program “BayLu25”, contributes to the environmental protection objectives of “Flightpath 2050” with respect to its noise reduction and environmental compatibility objectives of aircraft engines supporting the development of hydrogen engines.

Type: Collaborative project: Combustion dynamics of RQL combustion chambers
Funding: Bavarian Ministry of Economic Affairs, Regional Development and Energy
Funding code: BLU-2109-0012 / BayLu21-007-B
Runtime: 31.12.2021 - 31.12.2024
Website: Powering Aviation - Professur für Sustainable Future Mobility
Contact: Thuy An Do, Ángel Brito Gadeschi

H2 Combustion

Thermoacoustic Investigations of hydrogen in RQL combustion chambers

Compared to the combustion of kerosene-fueled aero engines, the degree of knowledge on hydrogen combustion in the aviation sector is still significantly low. This applies both for the conceptual level and also the optimization of promising approaches. In this project, the strategy of air staging with RQL (Rich-Quench-Lean) combustion, which is common in kerosene operation, is to be built upon. This approach significantly reduces pollutant emissions by means of multi-step combustion. Due to the highly different physical and chemical properties of hydrogen compared to kerosene, the behavior of innovative injection and staging scenarios suitable for hydrogen combustion will be investigated. In this context, the steady-state behavior, such as mixture formation and heat release distribution, as well as the transient behavior with respect to ignition, start-up, and safe shutdown, are examined. In addition, a high degree of attention will be paid to possible thermoacoustic combustion instabilities. The project is part of a larger research network in order to progress towards the safe and reliable combustor technology of the future for hydrogen propulsion.

Type: Collaborative project: Adaptation of the Rich-Quench-Lean principle to hydrogen-powered combustion chambers
Funding: Federal Ministry for Economic Affairs and Climate Action
Funding code: 20M2106C
Runtime: until 31.03.2026
Website: Powering Aviation - Professur für Sustainable Future Mobility
Contact: Benjamin Kölbl , Jannes Papenbrock 

Combustion process of H2 /CO/air mixtures

Determination of Characteristics of Slow to Fast H2-CO Combustion and Derivation of Risk Criteria

Conditions that might jeopardize the integrity of the containment in nuclear power plants can occur for example, if the fuel rods are damaged and H₂ is formed through metal oxidation reactions – particularly zirconium oxidation. Further, concrete-melt interaction (Molten Core Concrete Interaction - MCCI) can occur, in which CO is released in addition to H₂. Due to buoyancy effects, the gas mixture accumulates under the roof of the building establishing a stratified, semi confined gas layer. If H₂ or H₂/CO is present together with oxygen (O₂) in a sufficient concentration, ignition by hot surfaces or sparks is highly probable. The combustion process that follows might increase the pressure and temperature. In particular, fast turbulent-accelerated combustion and deflagration to detonation transition (DDT) or detonation are safety relevant, since related high local pressure peaks might damage the integrity of building structure. In worst case assumptions the outer barrier between the nuclear inventory and the environment might be destroyed, e.g., Fukushima 2011 [1].

Aiming to avoid similar severe accident events in the future, the present research project H2CORisk is going to improve the scientific understanding by providing new experimental insights into deflagrative combustion processes of H₂/CO/air-mixtures in partial containment. Specifically, conventional and optical measurement techniques are going to be used to obtain results that allow for the derivation of a sigma criterion for flame acceleration. Furthermore, the experimental results are going to be used for validating simulation results generated by an OpenFoam based CFD code under development at the Chair of Thermodynamics, TUM. H2CORisk is part of the KEK program (Competence preservation in Nuclear Technology at GRS).

[1] R. Gauntt, D. Kalinich, J. Cardoni, J. Phillips, A. Goldmann, S. Pickering, M. Francis, K. Robb, L. Ott, D. Wang, et al. Fukushima daiichi accident study (status as of april 2012). Sandia National Laboratory Report, SAND2012-6173, Albuquerque, NM, 2012

Type: Initiative “Maintaining competence in Nuclear Technology ”
Funding: Federal Ministry for Economic Affairs and Climate Action
Funding code: 1501642
Runtime: 01.12.2021 - 30.11.2024
Website: Powering Aviation - Professur für Sustainable Future Mobility
Contact: Kajetan Planötscher 

• LaBreVer Prüfstand
• ViFlumiLu Prüfstand 
• GraVent Prüfstand

The module "Sustainability in Aviation - Destination Green?" focuses on aviation stakeholders’ efforts in supporting the United Nations Sustainable Development Goals (UN-SDG) with emphasis on climate action based on life cycle thinking strategies. After discussing the UN-SDG and their implication for aviation, we will summarize and discuss scientific research on the current and expected future impact of aviation on climate change, e.g., contrail formation, radiative forcing, and local air quality until the year 2050 and beyond. An in-depth introduction to the relevant combustion physics and chemistry, with no prior knowledge assumed, will be given. Then, we will analyze promising options to reduce aircraft noise and CO2 emissions as well as to improve local air quality, i.e., technology, operational improvements, market-based measures, and sustainable alternative fuels.

More information: TUMonline

Alternate fuels form an important part of the existing and future solutions to sustainability. Hence, understanding how these fuels combust and produce green house gases is of importance. This course introduces the chemistry required to obtain this understanding. The course starts with basics of thermodynamics, fuels and chemistry (no prior knowledge in chemical kinetics is assumed) and slowly advances towards a detailed understanding of the reactions involved during the combustion of fuels. The exercises in the course are designed to start from the basics and then advance towards introducing and using chemical kinetic tools like RMG (reaction mechanism generator) and Cantera for the creation and analysis of the reaction mechanisms of combustion of the fuels. The course also introduces the combustion chemistry of sustainable aviation fuels, oxygenated fuels, ammonia, nitrogen oxides and aromatics (responsible for soot). By the end of the course, students would be able to create and reduce chemical kinetic mechanisms.

More information: TUMonline