FRANCIS TURBINE RUNNER Russian patent published in 2001 - IPC

FIELD: runners for hydraulic turbines running under head greatly deviating from rated value. SUBSTANCE: runner has device for erosion protection of its blades incorporating water intake channel running through runner shaft and header with outgoing pipes running along each blade to convey air to flow-path air admission devices. These devices are made in the form of hollow fins each stretching from entrance edge of blade towards current line in flow path under rated conditions; there is at least one air-vent hole in exit edge. Each blade has front edge of its fin spaced from hub through 0.2-0.8 of blade entrance edge projection onto runner axis; fin length equals 0.05-02 of nominal diameter of runner. EFFECT: augmented suppression of cavitation processes in turbine running under conditions other than those rated. 3 dwg