AERODYNAMIC OPTIMIZATION OF THE NOZZLE FOR THE LAST STAGE OF STEAM TURBINE

In order to meet the requirements of rising energy demand, one goal in the design process of modern steam turbines is to achieve high efficiencies. A major gain in efficiency is expected from the optimization of the last stage of a low pressure turbine (LP). This paper focuses on aerodynamic study by compound lean, axial sweep and hub end-wall of nozzle. The objective function is to maximize efficiency and minimize the leaving losses under the assumption of constant mass flow rate. The aerodynamic design process involves commercial 3D CFD tools. The maximization of the objective functions is achieved by means of a Design of Experiment (DoE) method "Optimal Space Filling" based on "Latin Hypercube Sampling". Finally, the optimized design is analyzed by a transient (Time Transfoiuiation) CFD simulation. Furthermore, the detailed flow pattern of the optimized and the initial design is analyzed and compared.