Handbook of Turbomachinery Second Edition Revised - Ventech!

Table 4 Typical Values of Critical Cavitation Coefficients for Francis and
Propeller Turbines [11]
NOMENCLATURE
A ¼ surface area.
D ¼ diameter of the rotor (characteristic dimension).
E ¼ specific energy.
g ¼ acceleration due to gravity.
H ¼ head on the machine.
_m ¼ mass flow rate.
N ¼ rotational speed of the rotor (rpm).
Ns ¼ dimensional specific speed.
ns ¼ dimensionless specific speed.
P ¼ power.
Q ¼ volumetric flow rate.
T ¼ torque.
~V ¼ absolute velocity of fluid.
Vu ¼ tangential velocity component.
Vz ¼ axial velocity component.
Vf ¼ radial velocity component.
v ¼ volume.
Greek Symbols
Turbine Type
Francis Francis Francis Francis Francis Kaplan Kaplan Kaplan
Ns 20 40 60 80 100 100 150 200
sc 0.025 0.1 0.23 0.4 0.64 0.43 0.73 1.5
a ¼ angle made by wicket gates.
b ¼ blade angle.
m ¼ viscosity of the fluid.
f ¼ speed ratio ¼ u=V.
r ¼ density.
pi ¼ dimensionless groups.
o ¼ angular velocity of rotor ¼ 2pN=60.
Copyright © 2003 Marcel Dekker, Inc.