Spiral Case

Spiral Case

 

in a hydroturbine, a housing designed to provide uniform water intake around the entire circumference of the distributor, that is, to permit all the guide vanes to be held in an axially symmetrical position. The cross section of a spiral case narrows at a constant rate downstream. Hydroelectric power plants operating under heads greater than 50–60 m use steel spiral cases with circular cross sections that shroud the stator almost completely. Spiral cases used with lower heads are made of reinforced concrete; they shroud approximately 225° of the stator’s circumference, and their cross sections are T-shaped. Unlike other hydroturbine settings, for example, open settings, spiral cases make it possible to locate a major part of the turbine mechanism outside of the water, which improves the turbine’s operating conditions.

References in periodicals archive ?
The Project Director said work on Spiral Case and Pet Liner of the Unit 17 had already been finished.
Official sources told reporter here said that work on Spiral Case and Pet Liner of the Unit 17 had already been completed.
Currently, the spiral case of the hydrogenerator unit 1 is being assembled at site.
Supplies a) 3 Double Francis identical to the existing (removal of parts of brittle cast iron) and amount instead of the old, including the following - The spiral case produced by casting or welding, : - The wheel (plans included) and its coupling to the turbine shaft, : - The turbine shaft forged steel with a flexible coupling, : - The bearings of the turbine and generator, : - The distributor with its guidelines, the regulating ring and the control system, : - The shaft seals, : - Mating turbine / generator : - 2 elbows vacuums.