Abstract
In the partial admission stage of steam turbines, a flange is placed to separate the nozzle box. The flange makes a large wake which causes the partial admission loss and the ventilation loss. Additionally, it causes a rotor lift oscillation which gives an extra stress to rotors. This paper presents a numerical study of unsteady flows in a partial admission stage. Seven cases with a different flange thickness were simulated. Thicker flanges resulted in better total efficiencies.
