Your Waterwheel Solution

The Kaplan Turbine

The kaplan turbine is a great development of early 20th century. The Kaplan is of the propeller type, similar to an airplane propeller. The kaplan's blades are adjustable for pitch and will handle a great variation of flow very efficiently. They are 90% or better in efficiency.and are used in place of the old (but great) Francis types in a good many of installations. They are very expensive and are used principally in large installations. The kaplan turbine, unlike all other propeller turbines, the runner's blades were movable. The guide vanes could also be turned and were automatically adjusted to any angle suitable to that of the blades by a combiner, so the turbine was efficient at different work-loads. A circular stay collar absorbed the compressive forces acting on the flume casing. All low-head, high discharge propeller turbines had to be given amply dimensioned draft tubes since the efficiency of the turbine depended on a strong pressure. If the height of the draft tube was too great, the water pressure around the runner became so low that cavitation posed a serious problem, and it was necessary to mount the runner below tail-race level