Improvement of turbine blade systems to reduce cavitation erosion

Conclusions1.When designing new runners it is necessary to combine theoretical, experimental, and on-site investigations.2.Various design modifications of runners were developed for reducing the rate of cavitation erosion of mixed-flow turbines and are being used successfully. The most prospective of them are:a rational form of the blade channel, which makes it possible to completely avoid or minimize cavitation erosion of the rear surfaces of blades in the region of the trailing edge near the lower rim;an increase of the radius of the fillet at the place of joining the leading edge of the blade with the lower rim for high-head runners (H=230–500 m) and moving the lower rim of the runner below the region of high meridian velocities for low-head runners (H=45–100 m) minimized cavitation erosion on the rear surface of the blades near the leading edge and lower rim.3.Cavitation erosion of runner blades of adjustable-blade turbines can be substantially reduced by rational design of the blades, including the leading and peripheral edges and by machining and finishing the form of the blades on a model.