Dirk Geyer
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View article: A generalized quantification method for bi-directional laser-induced fluorescence
A generalized quantification method for bi-directional laser-induced fluorescence Open
Quantitative measurements of minor species are essential for understanding flame propagation and emission formation, and for validation of chemical kinetic models. Laser-induced fluorescence-based methods are widely employed due to their a…
View article: High-Sensitivity Gas-Phase Raman Spectroscopy for Time-Resolved In Situ Analysis of Isotope Scrambling over Platinum Nanocatalysts
High-Sensitivity Gas-Phase Raman Spectroscopy for Time-Resolved In Situ Analysis of Isotope Scrambling over Platinum Nanocatalysts Open
In this study, we present a novel approach for time-resolved, in situ analysis of isotope scrambling reactions over platinum nanoparticle catalysts using high-sensitivity gas-phase Raman spectroscopy. A recently developed spectrometer setu…
View article: Flame and flow characteristics of lean premixed turbulent NH3/H2/N2 - air flames with increasing Karlovitz numbers
Flame and flow characteristics of lean premixed turbulent NH3/H2/N2 - air flames with increasing Karlovitz numbers Open
Premixed flames of partially cracked ammonia (NH3) hold significant promise for the decarbonization of internal combustion engines and gas turbines, since they can burn at a similar laminar flame speed to methane but have notably high blow…
View article: Experimental investigation of flame surface topology and temperature in lean premixed H2/air flames with 2D Rayleigh thermometry
Experimental investigation of flame surface topology and temperature in lean premixed H2/air flames with 2D Rayleigh thermometry Open
Two-dimensional (2D) Rayleigh scattering measurements are employed to investigate flame surface topology and temperature in lean premixed hydrogen/air turbulent jet flames as the Karlovitz number increases toward the distributed combustion…
View article: Soot and Flame Structures in Turbulent Partially Premixed Jet Flames of Pre-Evaporated Diesel Surrogates with Admixture of OMEn
Soot and Flame Structures in Turbulent Partially Premixed Jet Flames of Pre-Evaporated Diesel Surrogates with Admixture of OMEn Open
In this study, the soot formation and oxidation processes in different turbulent, pre-evaporated and partially premixed diesel surrogate flames are experimentally investigated. For this purpose, a piloted jet flame surrounded by an air co-…
View article: Structures of Laminar Lean Premixed H2/CH4/Air Polyhedral Flames: Effects of Flow Velocity, H2 Content and Equivalence Ratio
Structures of Laminar Lean Premixed H2/CH4/Air Polyhedral Flames: Effects of Flow Velocity, H2 Content and Equivalence Ratio Open
Polyhedral Bunsen flames, induced by hydrodynamic and thermo-diffusive instabilities, are characterized by periodic trough and cusp cellular structures along the conical flame front. In this study, the effects of flow velocity, hydrogen co…
Dual-track spectrometer design for 1D gas-phase Raman spectroscopy Open
In this study, a new design for a 1D gas-phase Raman spectrometer is presented, utilizing two dedicated tracks to image different properties of the measured signal onto a single charge-coupled device (CCD) chip. Two possible configurations…
Towards non-intrusive, quantitative N2O Raman measurements in ammonia flames Open
Understanding N2O formation and consumption in ammonia combustion is crucial in realizing the impact of ammonia as an alternative fuel to mitigate the impact of climate change. This study demonstrates the feasibility of using Raman spectro…
View article: Quantitative measurements of thermo-chemical states in turbulent lean and rich premixed NH3/H2/N2-air jet flames
Quantitative measurements of thermo-chemical states in turbulent lean and rich premixed NH3/H2/N2-air jet flames Open
Premixed piloted jet flames are an ideal generic configuration to examine the impact of turbulence on thermo-chemical states for staged-combustion systems, like rich-quench-lean technologies, which have been proposed for ammonia combustion…
View article: A joint numerical study of multi-regime turbulent combustion
A joint numerical study of multi-regime turbulent combustion Open
This article presents a joint numerical study on the Multi Regime Burner configuration. The burner design consists of three concentric inlet streams, which can be operated independently with different equivalence ratios, allowing the opera…
View article: Numerical analysis of multi-regime combustion using flamelet generated manifolds - a highly-resolved Large-Eddy Simulation of the Darmstadt multi-regime burner
Numerical analysis of multi-regime combustion using flamelet generated manifolds - a highly-resolved Large-Eddy Simulation of the Darmstadt multi-regime burner Open
Multi-regime effects occur due to the interaction of combustion phenomena such as partial premixing of reactants or product-recirculation and lead to the invalidity of idealization of local reaction zones by purely premixed or purely non-p…
View article: Cellular structures of laminar lean premixed H2/CH4/air polyhedral flames
Cellular structures of laminar lean premixed H2/CH4/air polyhedral flames Open
Fundamental studies on the effects of differential diffusion of hydrogen (H2) on flame structure are motivated as the high diffusivity of H2 presents challenges for the modeling and optimization of combustion systems. Polyhedral Bunsen fla…
View article: Extinction strain rates of premixed ammonia/hydrogen/nitrogen-air counterflow flames
Extinction strain rates of premixed ammonia/hydrogen/nitrogen-air counterflow flames Open
Chemical energy vectors will play a crucial role in the transition of the global energy system, due to their essential advantages in storing energy in form of gaseous, liquid, or solid fuels. Ammonia (NH3) has been identified as a highly p…
Experimental and numerical study of Zuppinger water wheel model Open
The Zuppinger water wheel, developed in the 1850s, is one of the most efficient water wheels and is commonly used for low-head hydropower generation. The high efficiencies of the wheel over a wide operating range, its simplicity in design …
Fuel Effects in Turbulent Premixed Pre-vaporised Alcohol/Air Jet Flames Open
To study combustion fundamentals of complex fuels under well-defined boundary conditions, a novel Temperature Controlled Jet Burner (TCJB) system is designed that can stabilise both gaseous or pre-vaporised liquid fuels. In a first experim…