3. INTRODUCTION
Invented by Prof. Viktor Kaplan of Austria during 1913 –
1922.
The Kaplan is of the propeller type, similar to an airplane
propeller.
The difference between the Propeller and Kaplan turbines is
that the Propeller turbine has fixed runner blades while the
Kaplan turbine has adjustable runner blades.
The kaplan's blades are adjustable for pitch and will handle a
great variation of flow very efficiently.
They are 90% or better in efficiency and are used in place
some of the old Francis types in a good many of installations.
The kaplan turbine, unlike all other turbines, the runner's
blades are movable.
The application of Kaplan turbines are from a head of 2m to
40m.
4. The Kaplan turbine is a water turbine which has
adjustable blades and is used for low heads and high
discharges.
The Kaplan turbine is an inward
flow reaction turbine, which means that the working
fluid changes pressure as it moves through the turbine
and gives up its energy.
The inlet is a scroll-shaped tube that wraps around
the turbine's wicket gate. Water is directed
tangentially through the wicket gate and spirals on to
a propeller shaped runner, causing it to spin.
The Kaplan turbine having drop height: 10 - 700 m
and Flow rate 4 - 55 m3
/s
7. Main Parts of a Kaplan Turbine
Scroll Casing:
It is the Casing in which guides the water and control
the water passage.
Guide Vanes: It is the blade in which guides the water
and control the water passage.
Draft Tube:After passing through the runner the
water is discharged to the tail race
through a gradually expanding tube.
Runner: It is connected to the shaft of the
generator.
Hub: It is the part of the runner in which
blades are mounted.
Governing Mechanism:it controls the position of guide
blades to affect the variation of flow rate when load
condition chnges.
19. Working Principle:
Water under pressure flush draft
tube through the guide vanes and
falls on the adjustable blades,
which enables adjust the flow and makes runner rotating.
After crossing propeller is the
kinetic energy of water converted
into rotational motion shaft.
The shaft powered generator
producing electric power.
20. Operation of kaplan turbine
The water from the penstocks enters the scroll casing and then
moves to the guide vanes.
From the guide vanes, the water turns through 90° and flows
axially through the runner.
For Kaplan Turbine, the shaft of the turbine is vertical. The lower
end of the shaft is made larger and is called ‘Hub’ or ‘Boss’.
The vanes are fixed on the hub and hence Hub acts as runner for
axial flow turbine.
The peripheral velocity velocity u of the runner vanes depends
upon the radius of the point under consideration & thus the blade
angle vary from the rim to the boss & the vanes are wraped,this is
necessary to ensure shock free entry &exit.
21. Classification of Kaplan Turbines
The Kaplan turbine can be divided in double and single
regulated turbines.
A Kaplan turbine with adjustable runner blades and
adjustable guide vanes is double regulated while one
with only adjustable runner blades is single regulated.
The advantage of the double regulated turbines is that
they can be used in a wider field.
The double regulated Kaplan turbines can work between
15% and 100% of the maximum design discharge;
the single regulated turbines can only work between
30% and 100% of the maximum design discharge.
22.
23. Velocity triangles and work done per second:
1.work done per second;
=ρQ[Vw1U1] {∵Vw2 =0}
2.work done per second per unit weight of water
striking=Vw1U1/g
3.Hydraulic eff.(�h)=Vw1U1/gH
4.Mechanical eff.(�m)=SP/RP
5.Overall eff.(�o)=SP/WP
27. Main Characteristic curve of Kaplan turbine
fig: unit power vs unit speed fig: overall eff.vs unit speed
28. Advantages:
It can be used for the sites having very low Head.
The advantage of the double regulated turbines is that they
can be used in a wider field.
At part loads there is reduced loss of efficiency.
Kaplan turbine has efficiency up to 90 percent
Because of small dimension of the power house
there is saving in excavation and civil Engineering works.
The frictional loss is less because of less number of blades.
Disadvantages:
Leakage of water into generator chamber and Condensation
are source of trouble.
Cost is very high for maintenance.
29. Applications:
Kaplan turbines are widely used throughout the world
for electrical power production. They cover the lowest
head hydro sites and are especially suited for high flow
conditions.
Inexpensive micro turbines on the Kaplan turbine model
are manufactured for individual power production with as
little as two feet of head.
Large Kaplan turbines are individually designed for each
site to operate at the highest possible efficiency, typically
over 90%. They are very expensive to design, manufacture
and install, but operate for decades.