Numerical Study on the Influence of Exhaust Structure on the Performance of a High Expansion Ratio Turbine

Abstract

A numerical simulation study on the influence of downstream pipe on turbine performance and flow is carried out for a high expansion ratio steam turbine. The abrupt change of the flow channel leads to severe reverse flow and increased back pressure, thus reduce the steam turbine power. The loss in the cylindrical cavity is up to 82% of the total loss downstream the steam turbine. By using a branch pipe to exhaust the steam of the passages downstream the intake area, the blast loss and mixing loss are significantly reduced for the non-intake passage, resulting a total reduction of 30.3%, and the power is increased by 5.3%. It provides a reference for the subsequent optimization design of flow channel.