Prediction of temperature distributions on hot components is important in development of a gas turbine combustion liner. The present study investigated conjugated heat transfer to obtain temperature distributions in a combustion liner with six combustion nozzles. 3D-numerical simulations using FVM commercial codes, Fluent and CFX were performed to calculate combustion and heat transfer distributions. The temperature distributions in the combustor liner were calculated by conjugation of conduction and convection (heat transfer coefficients) obtained by combustion and cooling flow analysis. The wall temperature was the highest on the attachment points of the combustion gas from combustion nozzles, but the temperature gradient was high at the after shell section with low wall temperature.
This paper presents thermal analyses of the cooling system of a transition piece, which is one of the primary hot components in a gas turbine engine. The thermal analyses include heat transfer distributions induced by heat and fluid flow, temperature, and thermal stresses. The purpose of this study is to provide basic thermal and structural information on transition piece, to facilitate their maintenance and repair. The study is carried out primarily by numerical methods, using the commercial software, Fluent and ANSYS. First, the combustion field in a combustion liner with nine fuel nozzles is analyzed to determine the inlet conditions of a transition piece. Using the results of this analysis, pressure distributions inside a transition piece are calculated. The outside of the transition piece in a dump diffuser system is also analyzed. Information on the pressure differences is then used to obtain data on cooling channel flow (one of the methods for cooling a transition piece). The cooling channels have exit holes that function as film-cooling holes. Thermal and flow analyses are carried out on the inside of a film-cooled transition piece. The results are used to investigate the adjacent temperatures and wall heat transfer coefficients inside the transition piece. Overall temperature and thermal stress distributions of the transition piece are obtained. These results will provide a direction to improve thermal design of transition piece.
High thermal efficiency of gas turbine systems is strongly related to the increase in the turbine inlet temperature, which is accompanied by the excess thermal load in the hot components of gas turbine. [Goldstein, 1971] Thus, various cooling techniques [Han et al., 2000] have been used to protect the main hot parts of the gas turbines. If an unsuitable cooling method is used, the local thermal crack and structural failure are yielded due to the thermal stress and the reduction of the material strength in high temperature. Therefore, the failure analyses as well as the thermal analyses for temperature, thermal stress, and life prediction are required for the effective thermal design of hot components. [Tinga et al., 2007; Kim et al., 2009] In this paper, we can find the locations of high stresses under the base load operation using the thermal analysis of the after section of combustor liners. Moreover, we can predict the lifetime from thermalmechanical stresses during the transient operations such as unit start-up and shutdown. Therefore, the objective of the present research is to find major causes of thermal damages affecting the lifetime induced by the temperature and thermal stress distributions.
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