Performance Deterioration Analysis of Aero-Derivative Gas Turbines

Abstract The gas turbines performance gradually degrades over time due to abnormal working conditions. The effects of these abnormal working conditions at full load operation differ from those at part load operation. Therefore, some researchers have dedicated their efforts to investigating gas turbine performance by considering full and part load operations. However, due to the time-consuming nature and complexity, they did not consider variable inlet guide vanes in the gas turbine performance model development. Additionally, the effects of drift in variable inlet guide vane and its combined impact with erosion and fouling on gas turbine thermal efficiency at both full and part load operations have not been studied. In this study, a performance model for a three-shaft gas turbine was developed, incorporating variable inlet guide vanes. After validating the performance model, the effects of fouling, erosion, and the drift in variable inlet guide vane and its combined effect with erosion and fouling on thermal efficiency were investigated at load conditions of 80%, 90%, and 100%. The results revealed that the highest deviation in thermal efficiency due to fouling occurs when the high-pressure compressor (HPC) is fouled, and the highest deviation in thermal efficiency due to erosion occurs when the high-pressure turbine (HPT) is eroded. Additionally, variable inlet guide vane up-drift offsets thermal deviations caused by fouling and erosion. The results are discussed following the plots. This study helps identify which components’ faults require more attention and should not be omitted in the development of diagnostics. Additionally, it highlights the gas turbine component most prone faults and enabling improvements in their design to mitigate performance declines caused by physical failures.