Handbook of Turbomachinery Second Edition Revised - Ventech!

where
and
y ¼ T 0 in
TSTD
d ¼ p0 in
pSTD
ð47Þ
ð48Þ
The standard conditions are usually taken to be 518.7 R and 14.7 psia.
Corrected speed is defined as
Ncorr ¼ N pffiffiffi ð49Þ
y
Equation (5) shows torque to be the product of flow rate and the change in
tangential velocity across the rotor. Corrected flow is defined above;
corrected velocities appear with y 1=2 in the denominator from the corrected
shaft speed. Therefore, corrected torque is defined as
Gcorr ¼ G
d
ð50Þ
The form of the corrected power is determined from the product of
corrected torque and corrected speed:
Pcorr ¼ P
d ffiffi p ð51Þ
y
These corrected quantities are used to reduce turbine performance data to
curves of constant-pressure ratio on two charts. Figure 11 presents typical
turbine performance maps using the corrected quantities. Figure 11(a)
presents corrected flow as afunction of corrected speed and pressure ratio,
while Fig. 11(b) shows corrected torque versus corrected speed and pressure
ratio. Characteristics typical of both radial-inflow and axial-flow turbines
are presented in Fig. 11.
AXIAL-FLOW TURBINE SIZING
Axial-Flow Turbine Performance Prediction
Prediction methods for axial-flow turbine performance methods can be
roughly broken into two groups according to Sieverding [10]. The first
group bases turbine stage performance on overall parameters such as work
coefficient and flow coefficient. These are most often used in preliminary
Copyright © 2003 Marcel Dekker, Inc.