Vibration-dampened discharge ring for bulb hydraulic turbines

Claim 1

A discharge ring for a hydraulic turbine having a rotary runner hub with a generally horizontal axis of rotation; a plurality of turbine blades extending radially from said runner; said discharge ring having a generally cylindrical inner ring surrounding said turbine blades with said inner ring defining a hydraulic passageway for guiding water past said turbine blades; the improvement comprising: a. a generally cylindrical outer ring of greater diameter than said inner ring and surrounding said inner ring; said outer ring being radially spaced from said inner ring and supported by a plurality of longitudinal and circumferential spacer ribs mounted on and projecting radially from said inner ring; b. said outer ring, inner ring and spacer ribs cooperating to define a plurality of cavities including highest elevation cavities and lowest elevation cavities within said discharge ring; vibration attenuation means comprising granular material within said cavities; c. means formed within a plurality of said spacer ribs permitting gravity flow material communication between said cavities; d. means for exposing highest elevation cavities comprising a fill plate sized to cover only said highest elevation cavities and means to removably secure said fill plate to said outer ring to complete said outer ring to cover said highest elevation cavities; and e. means for exposing said lowest elevation cavities comprising a discharge plate sized to cover said lowest elevation cavities and means to removably secure said discharge plate to said outer ring to complete said outer ring to cover said lowest elevation cavities whereby said highest elevation cavities may be exposed and said lowest elevation cavities unexposed to permit filling the cavities with said material by admitting said material to said highest elevation cavities with said material flowing by means of gravity to the cavities to increase the mass of said ring and abate vibration of said ring and said material may be discharged from said ring by exposing said lowest elevation cavities to decrease the weight of said ring and facilitate removal and maintenance of said ring.