Abstract
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.