fluid_mechanics

12.8 Turbines 675
Adjustable
guide vanes
Rotor
vanes
Casing
Tail race
Draft tube
(a)
(b)
F I G U R E 12.23 (a) Schematic diagram of a reaction turbine,
(b) photograph of a reaction turbine. (Courtesy of Voith Hydro, York, PA.)
California gold-mining days, is responsible for many of the still-used features of this type of turbine.
It is most efficient when operated with a large head 1for example, a water source from a lake
located significantly above the turbine nozzle2, which is converted into a relatively large velocity at
the exit of the nozzle. Among the many design considerations for such a turbine are the head loss
that occurs in the pipe 1the penstock2 transporting the water to the turbine, the design of the nozzle,
and the design of the buckets on the rotor.
b
r m
b
a
V 1
a
F I G U R E 12.24
Pelton wheel turbine bucket.
Details of