Propeller Hydroturbine

a reaction hydroturbine in which the power is varied by adjusting the stator vanes. The runner blades are rigidly attached to the shaft; that is, the geometry of the flow-through portion of the runner is fixed. Propeller hydroturbines are divided into axial and mixed-flow types according to the direction of the water flow in the runner. Axial types may be designed with diagonal, axial, or radial stators. Those with axial stators are used in direct-flow generators, in which the outer ends of the runner blades are rigidly attached to a ring. The mixed-flow type is the most common configuration; it features a smaller decrease in efficiency compared with the axial type when the load or head is changed.