Nomenclature
c = absolute velocity
Di = impeller inner diameter
Do = impeller outer diameter
q = dynamic pressure based on impeller tip speed
Q = volumetric flow rate
J = advance ratio
FB = blade body force
Fv = viscous body force
p = static pressure
Pt = total pressure
Pt = rotary stagnation pressure
Ri = impeller inner radius
Ro = impeller outer radius
rpm = revolution per minute
S = arc length measured around impeller
Tt = total temperature
Ui = blade speed at impeller inner radius
Uo = blade speed at impeller outer radius
Uj = propulsor exhaust velocity
Uw = wake velocity
UN = free-stream velocity
w = relative velocity
Ws = impeller shaft power
a = absolute flow angle
b = relative flow angle
b0 = blade metal angle
z = blade stagger angle
D = overall change
e = flow deflection (turning) angle
f = fan flow coefficient
l = power coefficient
O = impeller rotational speed
Zc = fan adiabatic compression efficiency
Zd = diffuser efficiency
Zp = propulsion efficiency
Zs =fan total-to-static efficiency
Zt = fan total efficiency
r = density
c = pressure coefficient
Subscripts
1 impeller first stage inlet station
2 impeller first stage outlet station
3 impeller second stage inlet station
4 impeller second stage outlet station
A region A
atm ambient condition
B region B
C region C
i inner blade station, also ideal
o outer blade station
r radial direction
s static
t total
v vortex (region C)
y circumferential direction
Others
e^r unit vector in radial direction
e^y unit vector in circumferential direction
n^ unit vector normal to mean streamline in impeller
region
o˜ total pressure loss coefficient