Water erosion experiments and protections for last-stage blades of steam turbine: A review

The low-pressure last-stage blades of steam turbines are highly susceptible to water droplet erosion (WDE), particularly under the combined effects of wet steam, flow-field distortion, and blowing-induced overheating. These interrelated multi-physical phenomena are further intensified under low-load conditions, significantly increasing the risk of blade erosion and potential fracture, thereby threatening the safe and stable operation of steam turbines. First, this review discusses the mechanisms of WDE in last-stage blades. Common experimental devices for WDE are then analyzed, with particular emphasis on two full-scale blade test rigs independently developed by us: a high-speed water-jet erosion system and dual-channel wet steam erosion platform. Key scientific issues in the WDE process of steam turbines, including droplet impact behavior, water film formation and evolution, and droplet dynamics, are systematically examined. Based on this, the current erosion resistance strategies for steam turbine blades are categorized and reviewed, with a comparative analysis of the advantages and limitations of each approach. Finally, future research priorities are proposed in three areas: optimization of experimental setups and techniques, development of novel protective materials, and establishment of standardized and shareable data frameworks. This review presents an integrated analysis of WDE challenges in steam turbines from the full research chain perspective of "mechanism investigation, experimental design, problem identification, protection strategies, and future outlook." This is conducive to promoting interdisciplinary research on WDE across the domains of materials science, fluid dynamics, mechanical engineering, and energy systems.