Advanced technologies for improving hydraulic performance and flow characteristics in hydroturbines: a comprehensive review

Hydroturbines have been harnessed for centuries to generate renewable energy, playing a crucial role in daily life, production, and efforts to reduce reliance on fossil fuels. However, turbine efficiency can be compromised by undesirable phenomena, such as tip leakage vortices, flow separation, vortex rope formation, and cavitation. These phenomena not only diminish turbine efficiency but also cause vibrations, noise, instability, and potential damage to components, ultimately shortening the turbine lifespan. Moreover, substantial investments in research and development for alternative renewable energy sources have significantly diminished the market share of hydropower. To support the continued maintenance and advancement of hydropower, this study highlights the advanced technologies applied to various hydroturbines, including Francis, Kaplan, pumps as turbines, and tidal turbines to mitigate undesirable phenomena through a series of previously conducted studies. The advantages and limitations of these advanced technologies are analyzed in detail in relation to key turbine components, such as the runner, guide vanes, and draft tube. The results demonstrate that the hydraulic performance and flow characteristics of hydroturbines can be enhanced through various approaches, including the use of winglets, grooves, fins, bionic protuberances, vortex generators, and air/water injection. In addition, this study discusses the potential for further development of these technologies and proposes new design concepts to enhance hydroturbine performance and eliminate phenomena that compromise operation stability.