Investigation of flow in a steam turbine exhaust hood with/without turbine exit conditions simulated

Experimental and numerical investigations for the flow in an exhaust hood model of large steam turbines have been carried out in order to understand the complex three-dimensional flow pattern existing in the hood and also to validate the CFD solver The model is a typical design for 300/600 MW steam turbines currently in operation. Static pressure at the diffuser tip and hub endwalls and at the hood outer casing is measured and nonuniform circumferential distributions of static pressure are noticed. The velocity field at the model exit is measured and compared with the numerical prediction. The multigrid multiblock three-dimensional Navier-Stokes solver used for the simulations is based upon the TVD Lax-Wendroff scheme and the Baldwin-Lomax turbulence model. Good agreement between numerical results and experimental data is demonstrated. It is found that the flow pattern and hood performance are very different with or without the turbine exit flow conditions simulated.