Abstract
Gas turbines come in different configurations, depending on the type of application required. The various gas turbine configurations exhibit different performance characteristics when operated under deteriorated conditions. This study aims to establish the effect of degradation on the performance characteristics exhibited by the different engine configurations. Gasturb software was employed to model and simulate the performance of different gas turbine configurations, namely single and twin shaft engines. Also, the single and twin shaft variants of the SGT 300 Siemens gas turbines data were used to model the different engine configurations. Consequently, arbitrary values of flow capacity and compressor efficiency percentage reductions referred to as moderate and heavy degraded conditions were implanted, to separately simulate the single and twin shaft engine configurations. When the heavily degraded condition was considered for the two engine configurations under conventional operating mode , the results show that fuel flow increased by 0.6% for the single shaft engine; while fuel flow dropped by 4.9% for the two shaft engine. Similarly, thermal efficiency drop of 2.8% for the twin shaft engine is higher than the single shaft engine of 0.6% for the conventional operating mode. When heavily degraded case was considered under variable speed operating mode, the percentage drop in fuel flow for the single shaft engine is 14.7% as against 4.9% for the twin shaft engine.

Key words: Compressor Degradation, Engine Configuration, Heat Rate, Simulations, Thermal Efficiency