Screw turbine

A screw turbine (also known as an Archimedean turbine, Archimedes screw generator or ASG, or Archimedes screw turbine or AST) is water turbine that converts the potential energy of water on an upstream level into work. This hydropower converter is driven by the weight of water, similar to water wheels, and can be considered as a quasi-static pressure machine. Archimedes screw generators operate in a wide range of flows (0.01 ${\displaystyle m^{3}/s}$ to 14.5 ${\displaystyle m^{3}/s}$) and heads (0.1 m to 10 m), including low heads and moderate flow rates that are not ideal for traditional turbines and not occupied by high performance technologies.

Archimedes' screw can be used to generate power if they are driven by flowing fluid instead of lifting fluid. Water transiting the screw from high to low elevation generates a torque on the helical plane surfaces, causing the screw to rotate. The Archimedes screw generator consists of a rotor in the shape of an Archimedean screw which rotates in a semicircular trough. Water flows into the screw and its weight presses down onto the blades of the turbine, which in turn forces the turbine to turn. Water flows freely off the end of the screw into the river. The upper end of the screw is connected to a generator through a gearbox. The Archimedes screw is theoretically a reversible hydraulic machine, and there are examples of single installations where screws can be used alternately as pumps and generators.