Chapter-11 Axial Flow Turbine
Chapter-11 Axial Flow Turbine
Chapter-11 Axial Flow Turbine
in driver in electricity generation, in gas pipe booster stations and as a prime movers
2MW to 660MW
Po2<Po1
Diffuser: dynamic head into static pr.
Inlet: guide the flow from the supply sou
To the stator vanes with minimum loss in
Total pressure
of turbine inlets: Guide the flow from the supply source to the stator vanes with a minimum
total pressure
Induce a swirl component to the
flow so that a torque can be imparted
To the rotor blades-has number of curved
Acts as a transition between aerofoils called vanes that turn the flow
the small diameter of supply In the tangential direction.
duct and the larger diameter
Used in turbochargers
of the turbine
Tangential
entry scroll inlet
num inlet with radial or axial
entry
a) Inserted into disk using
for axial flow turbine
dovetail
b) Disk integral with blades-blisk
Cooling used in case of high temp.
Relative velocity
increase in rotor
Stage efficiency
Stage reaction
0% Reaction stage
=0.5(tan 3-tan 2)
r impulse blades, 2=45.5o , Reaction 2=18.9o
can be calculated if incidence is known and also R/ can be
lculated.
action blade: R/ decreases as incidence increases
=0.20 when i=0 and R/ =0.25 when i=10
mpulse blade: R/ =0 when i=0 and R/ =-0.25 when i=10
Profile loss with incidence
on of loss data
e geometry, incidence, S/C, H/C, t/C, Reynolds number, b.l parameter, turbulence)
rofile loss(associated with bl growth over blades) + annulus loss (associated with bl growth on the walls) +
due to non-uniformity of inlet flow) + tip cleance loss
at zero incidence is first estimated using profile drag curves for nozzle and impulse balding at various S/C a
For blades in between impulse and nozzle the profile loss is given by
For impulse and near impulse blades this equation is valid for 0.15<t/C<0.2
For t/C values higher than these the limiting loss should be taken.
For rotor blades replace 3b by 2 and 2 by 1
Secondary loss: