Thermoacoustic interactions between two axially-staged lean-premixed flames in a model gas turbine combustor

with Kyutae Kim, Associate Professor of Aerospace Engineering, KAIST

April 21st, 10:00 AM, 440 Goodwin Hall

Technological advancements in the design and operation of heavy-duty gas turbines have led to a remarkable increase in overall thermal efficiency over the past several decades, mainly driven by a progressive increase in turbine inlet temperatures and associated improvements in turbine blade cooling methods. From the perspective of combustor development, the transition from non-premixed to lean-premixed combustion systems has proven central to achieving combined cycle efficiency of approximately 64% levels, without increasing nitrogen oxides emissions. According to thermodynamic analyses, however, the development of more efficient gas turbine engines with higher than 65% net efficiency necessitates turbine inlet temperatures of ~ 2000 K, at which point conventional architectures are unable to meet stringent nitrogen oxides emission requirements, because of the exponential and linear dependencies of thermal NOx production on flame temperature and combustor residence time, respectively. This chemical kinetics-related fundamental limitation can be circumvented by means of axial fuel staging strategies, also referred to as sequential combustor architectures. The main purpose of the present investigation is to understand how an axial fuel-staged system behaves in a complex thermoacoustic environment, in comparison with single injection, non-staged, baseline conditions. Extensive measurements conducted over a broad parameter space demonstrate the mutually incompatible nature of the dynamics of two distinct reaction zones and the possibility of acoustically-decoupled eccentric interactions, and underscore the importance of the secondary injector’s axial position in relation to selective excitation processes.

Kyutae Kim is an Associate Professor of Aerospace Engineering at KAIST, and EIRC Director for Carbon Neutral Gas Turbine Combustion Technology. He received his PhD in Mechanical Engineering from Penn State in 2009. After completion of his PhD, he accepted a Marie Curie Fellowship at the University of Cambridge, and then he worked at General Electric, where he contributed to the development of GE’s advanced gas turbine engines, including GE9X and 9HA.01. In 2016, he joined KAIST. His current research efforts focus on (i) combustion instabilities in heavy-duty gas turbine combustors, including low- and high-frequency instabilities associated with bulk, longitudinal, and transverse modes; (ii) hydrogen/ammonia-based carbon-free and lowcarbon gas turbine combustion; (iii) physics-based and data-driven modeling, including reduced-order modeling, numerical simulations, machine-learning frameworks.