@article{FunkeBeckmann2022,
  author    = {Funke, Harald and Beckmann, Nils},
  title     = {Flexible fuel operation of a Dry-Low-NOx Micromix Combustor with Variable Hydrogen Methane Mixture},
  series = {International Journal of Gas Turbine, Propulsion and Power Systems},
  volume    = {13},
  journal   = {International Journal of Gas Turbine, Propulsion and Power Systems},
  number    = {2},
  issn      = {1882-5079},
  pages     = {1 -- 7},
  year      = {2022},
  abstract  = {The role of hydrogen (H2) as a carbon-free energy carrier is discussed since decades for reducing greenhouse gas emissions. As bridge technology towards a hydrogen-based energy supply, fuel mixtures of natural gas or methane (CH4) and hydrogen are possible. The paper presents the first test results of a low-emission Micromix combustor designed for flexible-fuel operation with variable H2/CH4 mixtures. The numerical and experimental approach for considering variable fuel mixtures instead of recently investigated pure hydrogen is described. In the experimental studies, a first generation FuelFlex Micromix combustor geometry is tested at atmospheric pressure at gas turbine operating conditions corresponding to part- and full-load. The H2/CH4 fuel mixture composition is varied between 57 and 100 vol.\% hydrogen content. Despite the challenges flexible-fuel operation poses onto the design of a combustion system, the evaluated FuelFlex Micromix prototype shows a significant low NOx performance},
  language  = {en}
}
@article{FunkeEschRoosen2022,
  author    = {Funke, Harald and Esch, Thomas and Roosen, Petra},
  title     = {Powertrain Adaptions for LPG Usage in General Aviation},
  series = {MTZ worldwide},
  volume    = {2022},
  journal   = {MTZ worldwide},
  number    = {83},
  publisher = {Springer Nature},
  address   = {Basel},
  doi       = {10.1007/s38313-021-0756-6},
  pages     = {58 -- 62},
  year      = {2022},
  abstract  = {In general aviation, too, it is desirable to be able to operate existing internal combustion engines with fuels that produce less CO₂ than Avgas 100LL being widely used today It can be assumed that, in comparison, the fuels CNG, LPG or LNG, which are gaseous under normal conditions, produce significantly lower emissions. Necessary propulsion system adaptations were investigated as part of a research project at Aachen University of Applied Sciences.},
  language  = {en}
}
@article{FunkeEschRoosen2022,
  author    = {Funke, Harald and Esch, Thomas and Roosen, Petra},
  title     = {Antriebssystemanpassungen zur Verwendung von LPG als Flugkraftstoff},
  series = {Motortechnische Zeitschrift (MTZ)},
  volume    = {2022},
  journal   = {Motortechnische Zeitschrift (MTZ)},
  number    = {83},
  publisher = {Springer Nature},
  address   = {Basel},
  doi       = {10.1007/s35146-021-0778-2},
  pages     = {58 -- 62},
  year      = {2022},
  abstract  = {Auch in der allgemeinen Luftfahrt w{\"a}re es w{\"u}nschenswert, die bereits vorhandenen Verbrennungsmotoren mit weniger CO₂-tr{\"a}chtigen Kraftstoffen als dem heute weit verbreiteten Avgas 100LL betreiben zu k{\"o}nnen. Es ist anzunehmen, dass im Vergleich die unter Normalbedingungen gasf{\"o}rmigen Kraftstoffe CNG, LPG oder LNG deutlich weniger Emissionen produzieren. Erforderliche Antriebssystemanpassungen wurden im Rahmen eines Forschungsprojekts an der FH Aachen untersucht.},
  language  = {de}
}
@article{DickhoffHorikawaFunke2021,
  author    = {Dickhoff, Jens and Horikawa, Atsushi and Funke, Harald},
  title     = {Hydrogen Combustion - new DLE Combustor Addresses NOx Emissions and Flashback},
  series = {Turbomachinery international : the global journal of energy equipment},
  volume    = {62},
  journal   = {Turbomachinery international : the global journal of energy equipment},
  number    = {4},
  publisher = {MJH Life Sciences},
  address   = {Cranbury},
  issn      = {2767-2328},
  pages     = {26 -- 27},
  year      = {2021},
  language  = {en}
}
@article{FunkeBeckmannKeinzetal.2019,
  author    = {Funke, Harald and Beckmann, Nils and Keinz, Jan and Abanteriba, Sylvester},
  title     = {Numerical and Experimental Evaluation of a Dual-Fuel Dry-Low-NOx Micromix Combustor for Industrial Gas Turbine Applications},
  series = {Journal of Thermal Science and Engineering Applications},
  volume    = {11},
  journal   = {Journal of Thermal Science and Engineering Applications},
  number    = {1},
  publisher = {ASME},
  address   = {New York},
  issn      = {19485085},
  doi       = {10.1115/1.4041495},
  pages     = {011015},
  year      = {2019},
  language  = {en}
}
@article{FunkeBeckmannAbanteriba2019,
  author    = {Funke, Harald and Beckmann, Nils and Abanteriba, Sylvester},
  title     = {An overview on dry low NOx micromix combustor development for hydrogen-rich gas turbine applications},
  series = {International Journal of Hydrogen Energy},
  volume    = {44},
  journal   = {International Journal of Hydrogen Energy},
  number    = {13},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0360-3199},
  doi       = {10.1016/j.ijhydene.2019.01.161},
  pages     = {6978 -- 6990},
  year      = {2019},
  language  = {en}
}
@article{FunkeBeckmannKeinzetal.2018,
  author    = {Funke, Harald and Beckmann, Nils and Keinz, Jan and Abanteriba, Sylvester},
  title     = {Comparison of Numerical Combustion Models for Hydrogen and Hydrogen-Rich Syngas Applied for Dry-Low-Nox-Micromix-Combustion},
  series = {Journal of Engineering for Gas Turbines and Power},
  volume    = {140},
  journal   = {Journal of Engineering for Gas Turbines and Power},
  number    = {8},
  publisher = {ASME},
  address   = {New York, NY},
  issn      = {0742-4795},
  doi       = {10.1115/1.4038882},
  pages     = {9 Seiten},
  year      = {2018},
  abstract  = {The Dry-Low-NOx (DLN) Micromix combustion technology has been developed as low emission combustion principle for industrial gas turbines fueled with hydrogen or syngas. The combustion process is based on the phenomenon of jet-in-crossflow-mixing (JICF). Fuel is injected perpendicular into the air-cross-flow and burned in a multitude of miniaturized, diffusion-like flames. The miniaturization of the flames leads to a significant reduction of NOx emissions due to the very short residence time of reactants in the flame. In the Micromix research approach, computational fluid dynamics (CFD) analyses are validated toward experimental results. The combination of numerical and experimental methods allows an efficient design and optimization of DLN Micromix combustors concerning combustion stability and low NOx emissions. The paper presents a comparison of several numerical combustion models for hydrogen and hydrogen-rich syngas. They differ in the complexity of the underlying reaction mechanism and the associated computational effort. The performance of a hybrid eddy-break-up (EBU) model with a one-step global reaction is compared to a complex chemistry model and a flamelet generated manifolds (FGM) model, both using detailed reaction schemes for hydrogen or syngas combustion. Validation of numerical results is based on exhaust gas compositions available from experimental investigation on DLN Micromix combustors. The conducted evaluation confirms that the applied detailed combustion mechanisms are able to predict the general physics of the DLN-Micromix combustion process accurately. The FGM method proved to be generally suitable to reduce the computational effort while maintaining the accuracy of detailed chemistry.},
  language  = {en}
}
@article{TekinAshikagaHorikawaetal.2018,
  author    = {Tekin, Nurettin and Ashikaga, Mitsugu and Horikawa, Atsushi and Funke, Harald},
  title     = {Enhancement of fuel flexibility of industrial gas turbines by development of innovative hydrogen combustion systems},
  series = {Gas for energy},
  journal   = {Gas for energy},
  number    = {2},
  publisher = {Vulkan-Verlag},
  address   = {Essen},
  pages     = {4},
  year      = {2018},
  abstract  = {For fuel flexibility enhancement hydrogen represents a possible alternative gas turbine fuel within future low emission power generation, in case of hydrogen production by the use of renewable energy sources such as wind energy or biomass. Kawasaki Heavy Industries, Ltd. (KHI) has research and development projects for future hydrogen society; production of hydrogen gas, refinement and liquefaction for transportation and storage, and utilization with gas turbine / gas engine for the generation of electricity. In the development of hydrogen gas turbines, a key technology is the stable and low NOx hydrogen combustion, especially Dry Low Emission (DLE) or Dry Low NOx (DLN) hydrogen combustion. Due to the large difference in the physical properties of hydrogen compared to other fuels such as natural gas, well established gas turbine combustion systems cannot be directly applied for DLE hydrogen combustion. Thus, the development of DLE hydrogen combustion technologies is an essential and challenging task for the future of hydrogen fueled gas turbines. The DLE Micro-Mix combustion principle for hydrogen fuel has been in development for many years to significantly reduce NOx emissions. This combustion principle is based on cross-flow mixing of air and gaseous hydrogen which reacts in multiple miniaturized "diffusion-type" flames. The major advantages of this combustion principle are the inherent safety against flashback and the low NOx-emissions due to a very short residence time of the reactants in the flame region of the micro-flames.},
  language  = {en}
}
@article{FunkeKeinzKustereretal.2017,
  author    = {Funke, Harald and Keinz, Jan and Kusterer, K. and Haj Ayed, A. and Kazari, M. and Kitajima, J. and Horikawa, A. and Okada, K.},
  title     = {Development and Testing of a Low NOX Micromix Combustion Chamber for an Industrial Gas Turbine},
  series = {International Journal of Gas Turbine, Propulsion and Power Systems},
  volume    = {9},
  journal   = {International Journal of Gas Turbine, Propulsion and Power Systems},
  number    = {1},
  issn      = {1882-5079},
  doi       = {10.38036/jgpp.9.1_27},
  pages     = {27 -- 36},
  year      = {2017},
  abstract  = {The Micromix combustion principle, based on cross-flow mixing of air and hydrogen, promises low emission applications in future gas turbines. The Micromix combustion takes place in several hundreds of miniaturized diffusion-type micro-flames. The major advantage is the inherent safety against flash-back and low NOx-emissions due to a very short residence time of reactants in the flame region. The paper gives insight into the Micromix design and scaling procedure for different energy densities and the interaction of scaling laws and key design drivers in gas turbine integration. Numerical studies, experimental testing, gas turbine integration and interface considerations are evaluated. The aerodynamic stabilization of the miniaturized flamelets and the resulting flow field, flame structure and NOx formation are analysed experimentally and numerically. The results show and confirm the successful adaption of the low NOx Micromix characteristics for a range of different nozzle sizes, energy densities and thermal power output.},
  language  = {de}
}
@article{AyedKustererFunkeetal.2017,
  author    = {Ayed, Anis Haj and Kusterer, Karsten and Funke, Harald and Keinz, Jan and Bohn, D.},
  title     = {CFD based exploration of the dry-low-NOx hydrogen micromix combustion technology at increased energy densities},
  series = {Propulsion and Power Research},
  volume    = {6},
  journal   = {Propulsion and Power Research},
  number    = {1},
  publisher = {Elsevier},
  address   = {Amsterdam},
  isbn      = {2212-540X},
  doi       = {10.1016/j.jppr.2017.01.005},
  pages     = {15 -- 24},
  year      = {2017},
  language  = {en}
}
@article{FunkeKeinzKustereretal.2016,
  author    = {Funke, Harald and Keinz, Jan and Kusterer, Karsten and Ayed, Anis Haj and Kazari, Masahide and Kitajima, Junichi and Horikawa, Atsushi and Okada, Kunio},
  title     = {Experimental and Numerical Study on Optimizing the Dry Low NOₓ Micromix Hydrogen Combustion Principle for Industrial Gas Turbine Applications},
  series = {Journal of Thermal Science and Engineering Applications},
  volume    = {9},
  journal   = {Journal of Thermal Science and Engineering Applications},
  number    = {2},
  publisher = {ASME},
  address   = {New York, NY},
  issn      = {1948-5093},
  doi       = {10.1115/1.4034849},
  pages     = {021001 -- 021001-10},
  year      = {2016},
  abstract  = {Combined with the use of renewable energy sources for its production, hydrogen represents a possible alternative gas turbine fuel for future low-emission power generation. Due to the difference in the physical properties of hydrogen compared to other fuels such as natural gas, well-established gas turbine combustion systems cannot be directly applied to dry low NOₓ (DLN) hydrogen combustion. The DLN micromix combustion of hydrogen has been under development for many years, since it has the promise to significantly reduce NOₓ emissions. This combustion principle for air-breathing engines is based on crossflow mixing of air and gaseous hydrogen. Air and hydrogen react in multiple miniaturized diffusion-type flames with an inherent safety against flashback and with low NOₓ emissions due to a very short residence time of the reactants in the flame region. The paper presents an advanced DLN micromix hydrogen application. The experimental and numerical study shows a combustor configuration with a significantly reduced number of enlarged fuel injectors with high-thermal power output at constant energy density. Larger fuel injectors reduce manufacturing costs, are more robust and less sensitive to fuel contamination and blockage in industrial environments. The experimental and numerical results confirm the successful application of high-energy injectors, while the DLN micromix characteristics of the design point, under part-load conditions, and under off-design operation are maintained. Atmospheric test rig data on NOₓ emissions, optical flame-structure, and combustor material temperatures are compared to numerical simulations and show good agreement. The impact of the applied scaling and design laws on the miniaturized micromix flamelets is particularly investigated numerically for the resulting flow field, the flame-structure, and NOₓ formation.},
  language  = {en}
}
@article{AyedKustererFunkeetal.2016,
  author    = {Ayed, Anis Haj and Kusterer, Karsten and Funke, Harald and Keinz, Jan},
  title     = {CFD Based Improvement of the DLN Hydrogen Micromix Combustion Technology at Increased Energy Densities},
  series = {American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS)},
  volume    = {26},
  journal   = {American Scientific Research Journal for Engineering, Technology, and Sciences (ASRJETS)},
  number    = {3},
  publisher = {GSSRR},
  issn      = {2313-4402},
  pages     = {290 -- 303},
  year      = {2016},
  abstract  = {Combined with the use of renewable energy sources for its production, Hydrogen represents a possible alternative gas turbine fuel within future low emission power generation. Due to the large difference in the physical properties of Hydrogen compared to other fuels such as natural gas, well established gas turbine combustion systems cannot be directly applied for Dry Low NOx (DLN) Hydrogen combustion. Thus, the development of DLN combustion technologies is an essential and challenging task for the future of Hydrogen fuelled gas turbines. The DLN Micromix combustion principle for hydrogen fuel has been developed to significantly reduce NOx-emissions. This combustion principle is based on cross-flow mixing of air and gaseous hydrogen which reacts in multiple miniaturized diffusion-type flames. The major advantages of this combustion principle are the inherent safety against flash-back and the low NOx-emissions due to a very short residence time of reactants in the flame region of the micro-flames. The Micromix Combustion technology has been already proven experimentally and numerically for pure Hydrogen fuel operation at different energy density levels. The aim of the present study is to analyze the influence of different geometry parameter variations on the flame structure and the NOx emission and to identify the most relevant design parameters, aiming to provide a physical understanding of the Micromix flame sensitivity to the burner design and identify further optimization potential of this innovative combustion technology while increasing its energy density and making it mature enough for real gas turbine application. The study reveals great optimization potential of the Micromix Combustion technology with respect to the DLN characteristics and gives insight into the impact of geometry modifications on flame structure and NOx emission. This allows to further increase the energy density of the Micromix burners and to integrate this technology in industrial gas turbines.},
  language  = {en}
}
@article{FunkeBeckmannKeinzetal.2016,
  author    = {Funke, Harald and Beckmann, Nils and Keinz, Jan and Abanteriba, Sylvester},
  title     = {Comparison of Numerical Combustion Models for Hydrogen and Hydrogen-Rich Syngas Applied for Dry-Low-NOx-Micromix-Combustion},
  series = {ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition Volume 4A: Combustion, Fuels and Emissions Seoul, South Korea, June 13-17, 2016},
  journal   = {ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition Volume 4A: Combustion, Fuels and Emissions Seoul, South Korea, June 13-17, 2016},
  publisher = {ASME},
  address   = {New York, NY},
  isbn      = {978-0-7918-4975-0},
  doi       = {10.1115/GT2016-56430},
  pages     = {12},
  year      = {2016},
  abstract  = {The Dry-Low-NOₓ (DLN) Micromix combustion technology has been developed as low emission combustion principle for industrial gas turbines fueled with hydrogen or syngas. The combustion process is based on the phenomenon of jet-in-crossflow-mixing. Fuel is injected perpendicular into the air-cross-flow and burned in a multitude of miniaturized, diffusion-like flames. The miniaturization of the flames leads to a significant reduction of NOₓ emissions due to the very short residence time of reactants in the flame. In the Micromix research approach, CFD analyses are validated towards experimental results. The combination of numerical and experimental methods allows an efficient design and optimization of DLN Micromix combustors concerning combustion stability and low NOₓ emissions. The paper presents a comparison of several numerical combustion models for hydrogen and hydrogen-rich syngas. They differ in the complexity of the underlying reaction mechanism and the associated computational effort. For pure hydrogen combustion a one-step global reaction is applied using a hybrid Eddy-Break-up model that incorporates finite rate kinetics. The model is evaluated and compared to a detailed hydrogen combustion mechanism derived by Li et al. including 9 species and 19 reversible elementary reactions. Based on this mechanism, reduction of the computational effort is achieved by applying the Flamelet Generated Manifolds (FGM) method while the accuracy of the detailed reaction scheme is maintained. For hydrogen-rich syngas combustion (H₂-CO) numerical analyses based on a skeletal H₂/CO reaction mechanism derived by Hawkes et al. and a detailed reaction mechanism provided by Ranzi et al. are performed. The comparison between combustion models and the validation of numerical results is based on exhaust gas compositions available from experimental investigation on DLN Micromix combustors. The conducted evaluation confirms that the applied detailed combustion mechanisms are able to predict the general physics of the DLN-Micromix combustion process accurately. The Flamelet Generated Manifolds method proved to be generally suitable to reduce the computational effort while maintaining the accuracy of detailed chemistry. Especially for reaction mechanisms with a high number of species accuracy and computational effort can be balanced using the FGM model.},
  language  = {en}
}
@article{HajAyedKustererFunkeetal.2015,
  author    = {Haj Ayed, A. and Kusterer, K. and Funke, Harald and Keinz, Jan and Striegan, Constantin and Bohn, D.},
  title     = {Experimental and numerical investigations of the dry-low-NOx hydrogen micromix combustion chamber of an industrial gas turbine},
  series = {Propulsion and power research},
  volume    = {Vol. 4},
  journal   = {Propulsion and power research},
  number    = {Iss. 3},
  issn      = {2212-540X},
  doi       = {10.1016/j.jppr.2015.07.005},
  pages     = {123 -- 131},
  year      = {2015},
  language  = {en}
}
@article{HajAyedKustererFunkeetal.2015,
  author    = {Haj Ayed, A. and Kusterer, K. and Funke, Harald and Keinz, Jan and Striegan, Constantin and Bohn, D.},
  title     = {Improvement study for the dry-low-NOx hydrogen micromix combustion technology},
  series = {Propulsion and power research},
  volume    = {Vol. 4},
  journal   = {Propulsion and power research},
  number    = {Iss. 3},
  issn      = {2212-540X},
  doi       = {10.1016/j.jppr.2015.07.003},
  pages     = {132 -- 140},
  year      = {2015},
  language  = {en}
}
@article{FunkeDickhoffKeinzetal.2014,
  author    = {Funke, Harald and Dickhoff, J. and Keinz, Jan and Anis, H. A. and Parente, A. and Hendrick, P.},
  title     = {Experimental and numerical study of the micromix combustion principle applied for hydrogen and hydrogen-rich syngas as fuel with increased energy density for industrial gas turbine applications},
  series = {Energy procedia},
  journal   = {Energy procedia},
  number    = {61},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {1876-6102 (E-Journal)},
  doi       = {10.1016/j.egypro.2014.12.201},
  pages     = {1736 -- 1739},
  year      = {2014},
  abstract  = {The Dry Low NOx (DLN) Micromix combustion principle with increased energy density is adapted for the industrial gas turbine APU GTCP 36-300 using hydrogen and hydrogen-rich syngas with a composition of 90\%-Vol. hydrogen (H₂) and 10\%-Vol. carbon-monoxide (CO). Experimental and numerical studies of several combustor geometries for hydrogen and syngas show the successful advance of the DLN Micromix combustion from pure hydrogen to hydrogen-rich syngas. The impact of the different fuel properties on the combustion principle and aerodynamic flame stabilization design laws, flow field, flame structure and emission characteristics is investigated by numerical analysis using a hybrid Eddy Break Up combustion model and validated against experimental results.},
  language  = {en}
}
@article{EschFunkeRoosenetal.2011,
  author    = {Esch, Thomas and Funke, Harald and Roosen, Peter and Jarolimek, Ulrich},
  title     = {Biogene Automobilkraftstoffe in der allgemeinen Luftfahrt},
  series = {Motortechnische Zeitschrift (MTZ).},
  volume    = {72},
  journal   = {Motortechnische Zeitschrift (MTZ).},
  number    = {1},
  publisher = {Springer Nature},
  address   = {Basel},
  isbn      = {0024-8525},
  doi       = {10.1365/s35146-011-0013-7},
  pages     = {54 -- 59},
  year      = {2011},
  language  = {de}
}
@article{RobinsonFunkeHendrick2011,
  author    = {Robinson, A. E. and Funke, Harald and Hendrick, P.},
  title     = {Design and Testing of a Micromix Combustor With Recuperative Wall Cooling for a Hydrogen Fueled µ-Scale Gas Turbine},
  series = {Journal of engineering for gas turbines and power},
  volume    = {133},
  journal   = {Journal of engineering for gas turbines and power},
  number    = {8},
  publisher = {ASME},
  address   = {New York},
  isbn      = {1528-8919},
  pages     = {Art. Nr. 082301 , 8 Seiten},
  year      = {2011},
  language  = {en}
}
@article{FunkeBoernerFalketal.2011,
  author    = {Funke, Harald and B{\"o}rner, Sebastian and Falk, F. and Hendrick, P.},
  title     = {Control system modifications and their effects on the operation of a hydrogen-fueled Auxiliary Power Unit},
  series = {XX international symposium on air breathing engines 2011 : ISABE 2011, Gothenburg, Sweden, 12-16 September, 2011. Vol. 2.},
  journal   = {XX international symposium on air breathing engines 2011 : ISABE 2011, Gothenburg, Sweden, 12-16 September, 2011. Vol. 2.},
  publisher = {American Institute of Aeronautics and Astronautics},
  address   = {Reston, VA},
  isbn      = {9781618391803},
  pages     = {929 -- 938},
  year      = {2011},
  language  = {en}
}
@article{FunkeBoernerKrebsetal.2011,
  author    = {Funke, Harald and B{\"o}rner, Sebastian and Krebs, W. and Wolf, E.},
  title     = {Experimental Characterization of Low NOx Micromix Prototype Combustors for Industrial Gas Turbine Applications},
  series = {ASME Turbo Expo 2011 ; Vancouver, Canada, June 6-10, 2011},
  journal   = {ASME Turbo Expo 2011 ; Vancouver, Canada, June 6-10, 2011},
  year      = {2011},
  language  = {en}
}