Aerodynamics Prediction and Design of a Steam Turbine Exhaust Hood

Abstract

The exhaust hood of a low pressure steam turbine is a component that has the potential to be improved considerably in terms of aerodynamic efficiency. In the present study, flow structures in the exhaust hood model of the low pressure stream turbine are investigated with experimental measurement and numerical simulation. The flow field in a modern type of exhaust hood is illustrated. The flow field predicted by CFD is validated by experimental measurement. Then, this paper introduces an aerodynamic optimization system to further improve the pressure recovery capability of low pressure turbine exhaust hood. The optimization system is developed with the Kriging surrogate model and the CFD method. The aerodynamic benefit provided by the optimal exhaust hood is explained. Finally, to scrutinize the static pressure recovery capability of the optimized exhaust hood, a full-scale exhaust hood coupled with last three stages is used to numerically evaluate the optimal design at four different flow rates. It is demonstrated that the optimal design from the air model can be used in the actual exhaust hood in different operation conditions.