Andrea Gruber holds a doctoral degree in Mechanical Engineering from NTNU (2006), he is Senior Research Scientist at SINTEF Energy Research and Adjunct Professor at NTNU. His research interests are in the development and application of massively parallel direct numerical simulations (DNS), a high-fidelity numerical approach to accurately predict turbulent reactive flows. Over a period of nearly two decades and in a close and fruitful collaboration with combustion researchers from Sandia Lab (Livermore, CA), Dr. Gruber has initiated the deployment of DNS on some of the research challenges related to combustion of highly-reactive and non-standard fuels in gas turbines (hydrogen in particular). Pursuing industrial relevance within the framework of numerous national and international research initiatives (BIGH2, NCCS, DiHI-Tech, ENCAP, DECARBit) and in close partnership with the gas turbine industry (ALSTOM, Ansaldo Energia, Siemens), he has contributed to the fundamental understanding of key turbulence-chemistry interaction processes that play a major role in the achievement of clean and efficient power generation: design and optimization of fuel injection systems, flashback prediction and control, static and dynamic flame stabilization in conventional and staged combustion systems

 

Abstract

Fundamental Characteristics of Turbulence-Chemistry Interaction in Premixed NH3/H2/N2-Air Flames

Ongoing and future efforts to curb carbon dioxide emissions in fulfilling energy needs involve the use of carbon-free energy carriers such as hydrogen and ammonia. Motivated by the renewed interest in ammonia, several research groups have recently investigated the premixed combustion characteristics in laminar and turbulent flames comprised of NH3/H2/N2-air fuel-air blends, generated from partial ammonia decomposition. An interesting and rather unique aspect of these NH3/H2/N2-air blends, beside their obvious relevance to carbon-free industrial applications, is the fact that their nominal unstrained laminar premixed flame properties (for combustion in air) can be tailored to match those of methane-air premixed flames over a wide range of equivalence ratios, preheat temperatures and pressures. This affords an opportunity to construct an interesting comparison between nominally identical flames that differ solely by the molecular-diffusion characteristics of the fuel, something that is not easily achievable in hydrogen-enriched methane-air or syngas-air premixed flames. Direct Numerical Simulations (DNS) are used to gain insight on the fundamental characteristics of NH3/H2/N2-air flames and reveal the key role of molecular diffusion of light fast-diffusing species as molecular and atomic hydrogen in significant enhancement of the burning rate and resilience to blow out. Moreover, DNS results suggest that these mainly thermo-diffusive effects related to the presence of hydrogen in the burnable mixture are further enhanced at pressurized conditions.