A can type combustor with a rotating casing for an innovative micro gas turbine has been modeled, and the combustion characteristics were investigated. The simulations were performed using commercial code STAR-CD, in which a three-dimensional compressible k-ε turbulent flow model and a one-step overall chemical reaction between methane/air were used. The results include the detailed flame structure at different rotation speeds of outside casing, ranging from stationary to the maximum speed of 58,000 rpm of the design point. The airflows are baffled when entering the combustor through the linear holes due to the centrifugal force caused by the rotating casing, and the inlet flow angle is inclined. When the rotation is in the opposite direction of the swirling flows driven by the designed swirler, a shorter but broader recirculation zone and a concave shape flame are found at a higher rotating speed. At maximum rotating speed, the swirling flows are dominated by the rotating flows caused by the casing, especially downstream of the combustor. The combustor performance was also analyzed, indicating a higher combustion efficiency and higher exit temperature when the casing rotates, which benefits the performance of the gas turbine, but the cooling and possible hot spots for turbines are the primary concerns.
Influence of air distribution on combustion characteristics of a micro gas turbine fuelled by hydrogen-doped methane
