Page 299 - Fluid Mechanics and Thermodynamics of Turbomachinery

280 Fluid Mechanics, Thermodynamics of Turbomachinery
TABLE 9.3. Operating ranges of hydraulic turbines.

Pelton turbine Francis turbine Kaplan turbine
Specific speed (rad) 0.05 0.4 0.4 2.2 1.8 5.0
Head (m) 100 1770 20 900 6 70
Maximum power (MW) 500 800 300
Optimum efficiency, per cent 90 95 94
Regulation method Needle valve and Stagger angle of Stagger angle of rotor
deflector plate guide vanes bades
NB. Values shown in the table are only a rough guide and are subject to change.

The regimes of these turbine types are of some significance to the designer as they
indicate the most suitable choice of machine for an application once the specific
speed has been determined. In general low specific speed machines correspond
to low volume flow rates and high heads, whereas high specific speed machines
correspond to high volume flow rates and low heads. Table 9.3 summarises the
normal operating ranges for the specific speed, the effective head, the maximum
power and best efficiency for each type of turbine.
According to the experience of Sulzer Hydro Ltd., of Zurich, the application ranges
of the various types of turbines and turbine pumps (including some not mentioned

FIG. 9.2. Application ranges for various types of hydraulic turbomachines, as a plot of
Q vs H with lines of constant power determined assuming 0 D 0.8. (Courtesy Sulzer
Hydro Ltd., Zurich).