| 摘要 |
An adjustable draft tube is disclosed for a hydraulic turbine installation. The draft tube includes a pair of fabricated box piers which are positioned in a tailwater with the turbine outlet disposed between the piers. The piers are anchored to a tailwater floor and a powerhouse foundation wall. A roof is provided extending between opposing surfaces of the piers with an edge of the roof pivotally secured to the piers above the turbine outlet. The roof is pivotable between a first position with a downstream edge of the roof disposed beneath a predetermined low tailwater elevation and a second position with the downstream edge disposed between the low tailwater elevation and a predetermined high tailwater elevation.
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