On the left hand side of Figure 07.05.07, shown in red, is the 'neutral' track H of the actual water flow when crossing a cylindrical sector of 40 degrees (S40). Also shown in the top left hand diagram, (shown in dark blue) is the corresponding steep track D followed by the water when it flows across a cylindrical sector of 120 degrees (S120). In the lower left hand diagram, the corresponding paths for the flows across a conical turbine surface are shown.
However, if the flowing water is to be used to generate a driving force on the turbine cylinder or cone, then the diagrams on the right hand side of the Figure show the necessary arrangement. To achieve this aim, the pipes carrying the water need to be curved to a greater degree. Here, the curve of the pipes is increased by, say, an arbitrary additional 50 degrees to give a total of 90 degrees, as indicated by the curves marked L (shown in red) within sector S90.
Correspondingly, track K (shown in blue) is curved more sharply upwards with its sector reduced to a width of just 70 degrees (S70). This amount is the previous 120 degrees, reduced by our arbitrary 50 degrees. The upper right hand side diagram shows the design for a cylindrical turbine while the diagram below it shows the design for a conical turbine. The thin lines H and D show the original curves which would not apply any turning force to the turbine pipes were the water to flow through them. These paths could be called the 'neutral' tracks as they do not impart any thrust, and it takes the greater curvature shown by the thick lines to actually drive the turbine.
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