Spatial unsteady flow pattern in an old-design 200MW turbine exhaust hood and ways of its improvement

The numerical investigation of flow through the exhaust hood of a 200MW turbine under modernization is presented for a wide range of operational regimes and geometrical modifications. The solver applied is based on inviscid and non-heat conductive vapour, which is simulated as perfect gas of equivalent specific heat ratio. The calculation domain consists of axial-radial diffuser and space under casing including the intermediate chamber, the transversal and longitudinal walls, etc. The experience of such modelling and typical flow structures in the exhaust hood are discussed under consideration of various peculiarities of geometry.