| 摘要 |
A guide case is shown, for imparting a helical swirling motion to a flow of fluid, e.g. water, that is about to enter a turbine or propellor, for a small hydro-electricity generator. The case provides high turbine efficiency over a wide range of conditions, yet is compact, has no moving parts, and is easy to make from sheet metal. The case has an annular chamber into which an inlet duct feeds tangentially. As the water rotates around the annulus, it is conveyed axially along the chamber by a helical end of the chamber, arranged analogously to a square screw thread. The lead of the helix is such that there is neither interference nor a gap between water entering the chamber and water that has completed a revolution around the chamber.
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