Turbines
Machines which
convert hydraulic
energy(energy
possessed by water)
into mechanical
energy (which is
further converted
into electrical energy)
Pumps
Machines
which convert
mechanical
energy into
hydraulic
energy
• Hydraulic Turbines convert hydraulic energy
of water into mechanical energy which is
further converted into electrical energy. This
energy obtained is know as hydro-electric
power which is one of the cheapest forms of
energy generation.
• Hydraulic turbines consist of Pelton Wheel,
Francis and Kaplan Turbine.
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• In a Pelton Wheel or Pelton Turbine water
strikes the vanes along the tangent of the
runner and the energy available at the inlet of
the turbine is only kinetic energy, therefore it
is a tangential flow impulse turbine.
• This turbine is used for high heads and named
after L.A Pelton, an American engineer.
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Pelton Turbine: The First Titled Impulse Turbine
• Lester Allan Pelt on, considered to be the
father of modern day hydroelectric
power, was born in Vermilion Township,
Erie County, in Ohio.
• On September 5, 1829.
• Pelton embarked on an adventure in
search of gold.
• Shifted to California from Ohio in 1850,
he was 21 years old.
• After a failed quest for gold, he joined in
the gold mines as a millwright, and
carpenter at Camptonville, Yuba County,
California in 1864 .
• Nozzle: It controls the amount of water
striking the vanes of the runner.
• Casing: It is used to prevent splashing of water
and plays no part in power generation.
• Runner with buckets: Runner is a circular disc
on the periphery of which a number of evenly
spaced buckets are fixed.
• Breaking Jet: To stop the runner in short time
breaking jet is used.
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BUCKETS OR VANES
SPLITTER
RUNNER
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Arrangement of Jets
• The high speed water coming out of the nozzle strikes
the splitter which divides the jet into two equal
streams. These stream flow along the inner curve of
the bucket and leave it in the direction opposite to that
of incoming jet. The high pressure water can be
obtained from any water body situated at some height
or streams of water flowing down the hills.
• The change in momentum (direction as well as speed)
of water stream produces an impulse on the blades of
the wheel of Pelton Turbine. This impulse generates
the torque and rotation in the shaft of Pelton Turbine.
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u1
u
V = Absolute velocity of entering water
= Relative velocity of water
= Velocity of flow at inlet.
= Corresponding values at outlet
D= Diameter of wheel
d= Diameter of the nozzle
N= Revolution of th wheel in r.p.m.
H= Total head of water=hg-hf
In case,  =0°, =0°,
=v and
=v-u
The relation between two velocity triangles is
==
u = u1
Force exerted by the jet of water in the direction of motion fx=  av
( vw+vw1)
Work done=force*distance travelled per sec
= fx*u
=  av ( vw+vw1)*u
Ponts to be remembered
• 1. Velocity of Jet –
• Theoretical velocity,
• Actual velocity, V  Cv 2  g  H
• Value,, 0. 97 - 0 .99 (Friction loss)
• 2. Speed Ratio, — It represents the ratio of
the peripheral velocity to the theoretical
velocity of the jet.
u   2 g  H
  0.43  0.48
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3. Mean diameter of the wheel — D refers to
the diameter of the wheel measured upto the
centers of the buckets. The diameter is
calculated from the formula
U =∏ D n/60
D is the pitch or mean diameter.
4. Jet ratio — m represents the ratio of the
pitch circle diameter of the jet diameter. i.e.
m=D/d
5. Number of jets—Pelton wheel has one
nozzle or one jet. A number of nozzles may be
employed when more power is required.
• Francis Turbine is the first hydraulic turbine
with radial inflow. It was designed by an
American scientist James Francis. If the water
flows radially through the runner , from
outwards to inwards then it is known as an
inward radial flow turbine.
• Francis turbine is a reaction turbine as the
energy available at the inlet of the turbine is a
combination of kinetic and pressure energy.
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• CASING: The runner is completely enclosed in an airtight spiral casing. The casing and runner are always full
of water.
• GUIDE MECHANISM: It consists of a stationary circular
wheel on which stationary guide vanes are fixed. The
guide vanes allow the water to strike the vanes of the
runner without shock at inlet
• RUNNER: It is a circular wheel on which a series of
curved radial guide vanes are fixed.
• DRAFT TUBE: It is used for discharging water from the
outlet of the runner to the tail race.
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RUNNER
GUIDE WHEEL
MOVABLE VANES
STATIONARY GUIDE
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VANES
• Kaplan turbine is an axial flow reaction turbine.The
water flows through the runner of the turbine in an
axial direction and the energy at the inlet of the
turbine is the sum of kinetic and pressure energy .
• In an axial flow reaction turbine the shaft is vertical.
The lower end of the shaft is larger and is known as
‘hub’ or ‘boss’. It is on this hub that the vanes are
attached. If the vanes are adjustable then it is known as
kaplan Turbine and if the vanes are non adjustable then
it is known as Propeller Turbine.
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•Kaplan turbine is best suited where large quantity
of low head water is available.
•The main parts of a kaplan Turbine are:
1.Scroll Casing
2.Guide vane Mechanism
3.Hub with Vanes
4.Draft Tube
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SHAFT
VANES
HUBB OR
BOSS
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• The water enters the turbine through the guide vanes
which are aligned such as to give the flow a suitable
degree of swirl. The flow from guide vanes pass
through the curved passage which forces the radial
flow to axial direction.
• The axial flow of water with a component of swirl
applies force on the blades of the rotor and looses its
momentum, both linear and angular, producing torque
and rotation (their product is power) in the shaft. The
scheme for production of hydroelectricity by Kaplan
Turbine is same as that for Francis Turbine.
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GUIDE VANES
SHAFT
MOVABLE
VANES
HUBB OR BOSS
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• The draft tube is a pipe of gradually increasing
area which connects the outlet of the runner with
the tailrace. One end of the draft tube is
connected to the outlet of the runner while the
other end is submerged below the level of water
in the tail race.
• It creates a negative head at the outlet of the
runner thereby increasing the net head on the
turbine.
• It converts a large proportion of rejected kinetic
energy into useful pressure energy
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• It is the operation by which the speed of the
turbine is kept constant under all conditions of
working load. This is done automatically by a
governor which regulates the rate flow through
the turbines according to the changing load
conditions on the turbine.
• Governing of a turbine is absolutely necessary if
the turbine is coupled to an electric generator
which is required to run at constant speed under
all fluctuating load conditions.
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