Combustor modeling and design modification of a micro gas turbine combustor with a rotating casing for syngas fuel

This study is an extension of the previous study, which presents the rotation effects of casing on syngas combustion. When syngas was applied to achieve the power output of proposed micro gas turbine, high temperature flame moves towards the exit of the combustor. Consequently, the temperature and temperature fluctuation at combustor exit increases. In this study, geometry of the can combustor is modified for the syngas application. In modified design, diameter of the fuel injector, length of the primary zone, configuration of primary and dilution holes is modified. To perform the numerical calculation, computational model which consists of three-dimension compressible k- realizable turbulent flow model and presumed probability density function for combustion process invoking a laminar flamelet assumption generated by detailed chemical kinetics from GRI 3.0 is used. Two typical composition of syngas are used namely: H2-rich (H2:CO = 80:20) and equal molar (H2:CO = 50:50). The combustion characteristics and NOx emissions were investigated to understand the rotating effects of syngas combustion in the modified design of the can combustor. In the modified design, the high-temperature flame gets stabilized along the wall of the combustor for both composition of syngas. Unlike in the previous design, the high-temperature flame moves towards the exit of the combustor. The exit temperature and pattern factor dropped and reached the design requirements after the modification. The rotation of casing enhances the swirling strength, which benefits proper mixing of fuel and air and leads to reduction in pattern factor and NOx emissions.