xiii
List of Symbols
S
surface area
m
2
t
time
s
or
thickness of blades
m
T
temperature
K or °C
or
thrust force
N
u
blade speed (radius x rotational speed)
m/s
U
gravitational potential energy
m/s
v 0
inflow velocity
m/s
v e
energy reference velocity
m/s
w
flow velocity in relative frame
m/s
W
work per unit of time
J/s = W
x
coordinate along streamline
m
or
coordinate in axial direction
m
y
coordinate perpendicular to streamline
m
or
coordinate in circumferential direction
m
z
coordinate in vertical direction
m
or
coordinate in radial direction
m
Z
number of blades
–
α
angle of absolute velocity w.r.t. meridional plane
°
β
angle of relative velocity w.r.t. meridional plane
°
Γ
circulation along a contour
m
2
/s
δ
boundary layer thickness
m
W
∆
rotor work per unit of mass
J/kg
ε
Pfleiderer work reduction factor (3.23)
–
η i
internal efficiency
–
η m
mechanical efficiency
–
η p
polytropic efficiency
–
or
propulsive efficiency (12.7)
η s
isentropic efficiency
–
η sre
isentropic re-expansion efficiency (11.7)
–
η t
thermal efficiency (12.9)
–
η td
thermodynamic efficiency (12.9)
–
η tt
total-to-total isentropic efficiency
–
η v
volumetric efficiency
η ∞
infinitesimal efficiency
–
θ
angular coordinate
rad
or
flow turning angle
rad
κ
heat transfer coefficient (11.18)
J/kJK
λ
speed ratio (u/v 0 )
–