Outlet and Water Cylinder

In Figure 07.05.17, a horizontal axis turbine T is shown which has tooth-like turbine-blades TS as part of the cone. The main cone of the turbine is extended by the turbine inlet section TE. Opposite these surfaces is the hollow-cone of the conical housing wall KW (shown in grey) and it is attached to the main housing G (also shown shaded in grey). Water, (shown in light blue) flows between these surfaces in a rotating motion. This physical construction and operational movement is the same as in the previous examples.

In the previous examples of construction, it was suggested that the flow along the side cone-wall was directed into the turbine grooves just before exiting from the turbine cone. For this to be effective, it is necessary to have an adequate flow in the outlet region. Only practical experiments can determine what percentage of the free-flowing water is the most effective to directed into the turbine grooves at this point. For example, this diagram shows a design of outlet A where all of the water at the cone wall can flow off freely. Here, cone ridges produce a smoothly curving water flow across the surface of the turbine cone.

A new constructional element in this design is shown as ring B which runs all the way around the upper edge of the turbine cone. Water enters this 'round pipe' tangentially and does a U-turn of some 180 degrees. Previously, it was shown that water left the outlet at an angle of about 60 degrees, so water will enter this pipe by a spiral track. No matter what the angle of entry is, the water will exit from the 'round half-pipe' tangentially because of it's own motion generating centrifugal force (so, as drawn here, it will move towards the right hand side).

Sharp redirections like these ones, normally produce turbulent flows with corresponding major friction losses. This is because within any normal pipe bend, the inner flow path around the bend is much shorter than the outer flow path around the bend. But, in this case, there is no inner part of any such narrow bend, and the water keeps rotating in a cylindrical movement as it flows. Within these water-cylinders, flow layers of different radius and different turning-speeds balance out without friction. This 'all-around' pipe with the water rotating inside it, acts like a ball-bearing, so the flow from the outlet and the redirection of water towards the inlet is achieved with the minimum of frictional losses.

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