512 



HYDRAULICS AND ITS APPLICATIONS 



high part-gate efficiency which are unequalled by any other type, the 

 high first cost prohibits its use in many instances. The demand, particu- 

 larly in the United States, for a turbine suitable for low and medium 

 falls, which must above all things be cheap, and in which the efficiency 

 need not necessarily be very high, has led to the development of a type 

 of machine which, although for many years confined to the United States, 

 is at present being manufactured in some numbers in Great Britain and 

 to a less extent on the Continent. The Hercules and Victor low-pressure 

 turbines may be taken as representative of this class. 



These machines, which are almost invariably fitted with fixed guide 



FIG. 244. Runner for 15 in. Mixed-Flow Victor Turbine. 



vanes and regulated by means of the cylindrical gate or ring sluice, have 

 inward radial flow as in the Francis turbine. After the inlet the wheel 

 buckets are curved both laterally and vertically, the water in its 

 passage through the wheel tracing out a path which is approximately a 

 quadrant of a circle, and being finally discharged partly in an axial and 

 partly in an outward radial direction. 



Fig. 242 shows the general arrangement of an enclosed double hori- 

 zontal shaft turbine of this type, while Figs. 243 and 244 show details of 

 the guide vanes and runner of a Victor turbine, 1 as designed to develop 

 180 H.P. when running at 665 revolutions per minute under a head of 

 50 feet. The vanes at the outlet are spoon -shaped. By this type of 



1 By courtesy of the makers, the Platt Iron Works, Dayton, Ohio. 



