Combustion Characteristics of a Can Type Gas Turbine Combustor with Rotating Casing

• Main Authors: LIN.SHIAN-YI, 林憲義
• Other Authors: Hsin-Yi Shih
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/12094392213097179102

碩士 === 長庚大學 === 機械工程研究所 === 94 === The purpose of this study is to establish a numerical model for a can type gas turbine combustor with rotating casing and to analyze combustion characteristics by numerical simulations. A newly designed gas turbine combustor is installed inside the shaft (a hollow shaft) of gas turbine while the shaft functions as the casing of combustor. When the shaft (casing) rotates, the air will flow in both axial and circular directions between the liner and the casing. This circular airflow will influence the swirl when it enters the combustor. Generally speaking, swirl may enhance mixing of air and fuel, resulting in recirculation in the primary combustion zone. It has been shown the swirl can improve combustion efficiency and extend flammability limits. It can also decrease flame size, and reduce pollution emission. That is why swirl is widely used in gas turbine combustors. However, for the conventional designs of the combustor, the casing is usually static and the swirl is generated inside the combustor by a swirler. The effects of a rotating casing, when the swirl is generated inside as well as outside of a combustor, surely deserves investigation and clarification. The studies are conducted in both cold and thermal flow fields. In the cold flow field, gaseous fuel propane (C3H8) is mixed with air and the changes of flow field under various rotation speeds are analyzed to reveal the influence of a rotating casing on the swirl flow inside the combustor. In the thermal field, the combustion characteristics of propane/air and methane/air are shown to demonstrate the flame stabilization, temperature and species distributions, flow field profiles under a rotating casing at different rotating speeds. Finally, results of the numerical model are employed to investigate the combustor performane including combustion efficiency, pressure loss, pattern factor, hot spots at exit, and poor cooling locations, which can be used to improve the combustor design and the combustion performance for this new designed gas turbine engine. Keywords: Gas turbine combustion, can combustor, micro gas turbine, recirculation, swirl.