Performance of Evaporative Cycle Gas Turbines Derived from Aeroengines

Abstract

The modie cation of thethermodynamiccyclecould bean attractive opportunity for improving the performance of aeroderivative gas turbines. The simulation of a aeroderivative gas turbine modie ed to realize a nonintercooled regenerative water-injected (RWI) cycle is presented. The thermodynamic analysis of the RWI cycle shows that aeroderivative gas turbines with a pressure ratio from 16 to 20 can reach thermal efe ciency of 45%. The design of the enhanced gas turbine is carried out under the hypotheses that the compressor is unchanged and that the stator vanesofthetwo-stagehigh-pressureturbinearepartiallyopened to accommodateto thelargermasse owproduced by water injection. The other characteristics of the turbine stator blades (internal and external area and internal coolantpassages )andtherotorbladesaresupposed unchanged.Astage-by-stageoff-design model, including blade cooling and hydrodynamics, is introduced for predicting the performance of the modie ed high-pressure turbine. The effects produced by modie cation of the cycle are then evaluated. The off-design incidence angles at the rotor inlet of both the stages appear to limit the maximum amount of the water that can be injected per air mass unit. The increase of the blade temperature instead can be compensated by decreasing the turbine inlet temperature or by refrigerating the cooling air. The mathematical model adopted for simulating the on-design and the off-design behavior of the enhanced gas turbine is described.