Crossflow Turbine

A crossflow turbine is a water turbine in which the water passes transversely across the runner blades, entering at the edge of the turbine, flowing inward, and then exiting again on the opposite side, a double pass that both improves efficiency and helps the turbine clean itself of debris. Three engineers developed the design independently: the Australian Anthony Michell, who obtained patents in 1903, the Hungarian Donat Banki, who also contributed to the design, and the German Fritz Ossberger, who patented his own version in 1933 and founded the manufacturing company that still bears his name. The turbine suits sites with low head but high flow, runs at low speed, and holds a fairly constant efficiency across a wide range of loads, from one sixth to full capacity, which makes it well suited to small rivers whose flow varies with the seasons; today crossflow turbines are used mostly in mini and micro hydropower installations of less than 1,000 kilowatts and heads below 200 meters.