663 / 2019-04-27 06:46:29

A Numerical Study of Flow Pattern in a Deteriorated Gas Turbine Under Real Operating Condition

Gas turbine,blade deterioration,aerodynamics,maintenance,computational fluid dynamics,heat balance analysis

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A numerical study of aerodynamics in a deteriorated gas turbine was carried out. In the present study, a hybrid method of CFD simulation and heat balance analysis were used to estimate entire performance of the gas turbine cycle and local flow characteristics in the turbine section. Using this analysis method, flows in a deteriorated gas turbine was simulated under an operating condition, which were designated using the same procedure with that used in a real power plant. Previously, the degradation of the gas turbine performance due to blades deterioration had been observed. In the present study, flow patterns were observed in detail and detailed mechanisms underlying the degradation of the gas turbine performance were discussed. Influence of two kinds of deterioration on flow patterns were examined: the first was erosion of nozzle guide vanes in the first stage and the second was increase of rotor tip gap in the first stage. The results showed that the deterioration of nozzle guide vanes leaded to decrease of a Mach numbers and flow angles at the inlet of the following rotor blades. The increase in the rotor tip gap affected a loss generation of the following stage. Changes of flow patterns and its effects were discussed varying operating points of a gas turbine.