Numerical investigation of LP turbine-exhaust hood interaction in the steam turbine exhaust system

스팀터빈 Exhaust System에서 LP터빈과 Exhaust Hood 사이의 간섭에 대한 수치해석적 연구

Exhaust system of steam turbines consists of an annular diffuser and a collector and connects the last stage turbine and the condenser. The system is used to transfer the turbine leaving kinetic energy to potential energy while guiding the flow from turbine exit plane to the downstream condenser. In the steam turbine exhaust system, distorted pressure profile is arisen by the nonaxisymmetric collector structure at the diffuser outlet, and this distorted pressure is propagated to the last stage LP turbine exit plane through the diffuser, then the last stage LP turbine experiences asymmetric back pressure. It is known that the pressure recovery performance of diffuser is strongly influenced by diffuser inflow condition. In this study, the effect of exhaust system due to the changing of inlet flow condition is observed by using CFD, and the interaction of last stage LP turbine and exhaust system is investigated by using actuator disk model as modeling of turbine blade row of exhaust hood inlet.