The Francis turbine is a type of water turbine used for generating electricity in hydroelectric power plants. It was invented by James B. Francis in the 19th century and is designed to operate efficiently with a wide range of water flow rates. The turbine has a spiral casing that directs water to the runner, which is the rotating part that converts the kinetic energy of water into mechanical energy. This turbine is particularly effective for medium to high head applications, making it suitable for various hydroelectric projects. Its design allows for a high efficiency rate, often exceeding 90%, which contributes to its popularity in the renewable energy sector.