SPIRAL CASING FOR A HYDRAULIC TURBINE AND METHOD FOR ARRANGING A SPIRAL CASING

摘要

A spiral casing for a hydraulic turbine has been conceived including: an array of spiral segments defining a passage to direct liquid entering the casing to a runner in the turbine, the spiral segment extending at least partially around the runner and having an inner perimeter defining an opening to receive the runner, the cross- sectional areas of the spiral segments gradually decrease from an inlet one of the spiral segments to a last one of the spiral segments, wherein each of the spiral segments includes a gap aligned with the opening and the cross sections of the spiral segment do not correspond to a circular cross section; an inlet segment defining a passage to receive liquid to flow into the spiral segments, wherein the inlet segment is circular in cross section, and a transition segment connecting the inlet segment to one of the spiral segments and defining a passage to direct liquid passing from the inlet segment to the spiral segments, wherein the transition segment is non-circular in cross section along at least a portion of its length.