抄録
Water thin film is created on stationary blades as wet stream flow expands through the last few stages of Low Pressure (LP) steam turbine. It is torn off by high-speed steam flow and broken up into various size droplets. Some large-size and accordingly low-velocity droplets strike leading edges of rotating blades with almost circumferential velocity of them. This fact causes severe erosion damage and has been recognized as a limiting factor on the overall design of the turbine. Sequential motions of water film flow driven by a turbulent air flow from wave patterns on a wall to deformation and break-up patterns on a wall edge are recorded with a high-speed camera. It indicates the wave patterns in film flows dependence on an air stream velocity and also a strong correlation between the upstream wave patterns and the downstream deformation and break-up patterns.
