The document discusses the Francis turbine, which is the most commonly used water turbine today. It was invented in Lowell, Massachusetts by James Francis in 1849. He was able to redesign the existing Boyden turbine to significantly increase its efficiency from 65% to 88%. The key components of a Francis turbine include a scroll casing, guide vanes, runner, and draft tube. Water enters the scroll casing and is directed by the guide vanes to spin the radial vanes of the runner, which is connected to a shaft to power a generator. The draft tube recaptures pressure from the water exiting the runner. Francis turbines can operate over a wide range of heads from 10-650 meters and

1. Welcome
Dear viewers
Topic discussed: Francis Turbine
Name: ID:
Razin Sazzad Molla 13107010
1
13107010@iubat.edu
razin505@gmail.com

2. Hydraulic turbines (A brief overview) Machines that extract energy from fluid
stream are called turbines(Hydraulic turbines,
Steam turbines, Gas turbines). In hydraulic
turbines the working fluid is water and is
incompressible. Potential energy stored in
water at high head(hydro-power) is converted
in mechanical energy and used as prime
movers. Momentum of incoming water is
utilized.
 The mechanical energy developed by a
turbine is used in running an electric
generator which is directly coupled to the
shaft of the turbine. The power generated is
called hydroelectric power. In 2015
hydropower generated 16.6% of the world's
total electricity and 70% of all renewable
electricity
 Broadly classified in 2 groups according to the
action of water (ways of imparting energy
from water to turbine runner): Impulse
turbines & reaction turbines 2

3. Francis turbine
Francis turbines are the most common water turbine in use today. It is an Inward Flow
Reaction Turbine having Radial Discharge at Outlet. (i.e. Blade angle = 90). Modern Francis
Turbine is a mixed flow type turbine (i.e. Water enters the runner of the turbine in the
radial direction and leaves the runner in the axial direction).
It was developed by James B. Francis in Lowell, Massachusetts, (Mill City USA)
Operate in a water head from 10 to 650 meters (33 to 2,133 feet) and are primarily used
for electrical power production
The turbine powered generator power output generally ranges from 10 to 750 megawatts,
 Penstock (input pipes) diameters are between 1 and 10 meters (3 and 33 feet). The speed
range of the turbine is from 83 to 1000 rpm.
Wicket gates around the outside of the turbine's rotating runner adjust the water flow rate
through the turbine for different water flow rates and power production rates
Francis turbines are almost always mounted with the shaft vertical to keep water away
from the attached generator and to facilitate installation and maintenance access to it and
the turbine.
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4.  This turbine was invented by Sir
James B. Francis in Lowell,
Massachusetts, U.S.A.
 Studying the Boyden turbine ,Francis
was able to redesign it to increase
efficiency.
 Boyden Turbine could achieve a 65
percent efficiency.
 So, James France redesigned this
turbine and new turbine with 88%
efficiency was invented.
 This was known as ‘Francis turbine’.
Sir James B. Francis
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5. The Boyden Turbine
The Invention
Studying the Boyden turbine Francis was
able to redesign it to increase efficiency.
Constructing turbines as “sideways water
wheels,” Francis was able to achieve an
astounding 88 percent efficiency rate.
After further experimenting, Francis
developed the mixed flow reaction turbine
which later became an American standard.
Twenty-two of the “Francis turbines”
reside in Hoover Dam to this day.
His work on these turbines was later
published as The Lowell Hydraulic
Experiments in 1855.
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6. Components of Francis Turbine
The main parts of Francis Turbine are:
SCROLL CASING:
The runner is completely enclosed in an air-tight spiral casing. The casing and runner are always full of water.
GUIDE MECHANISM:
It consists of a circular wheel all round the runner of the turbine. The stationary guide vanes are fixed on the
guide wheel. The guide vanes allow the water to strike the vanes fixed on the runner without shock at inlet.
Also width between the two adjacent vanes can be altered so that amount of water striking the runner can be
varied.
RUNNER:
It is a circular wheel on which a series of Radial Curved Vanes are fixed. The vanes are so shaped that the water
enters and leaves the runner with out shock.
DRAFT TUBE:
The pressure at the exit of the runner of Reaction Turbine is generally less than atmospheric pressure. The
water at exit cannot be directly discharged to the tail race. A tube or pipe of gradually increasing area is used
for discharging water from the exit of turbine to the tail race. This tube of increasing area is called Draft Tube.
One end of the tube is connected to the outlet of runner while the other end is sub-merged below the level of
water in the tail-race.
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8. Scroll casing: the water from the penstock enters the scroll casing (spiral casing) which
completely surrounds the runner. It provides an even distribution of water around the
circumference of the turbine runner. The cross sectional area of the casing is gradually
decreased. The casing is made of cast steel, plate steel, concrete or concrete and steel
depending upon the pressure. 8

9. Speed ring or stay ring: from the
scroll casing the water passes
through speed ring. It consists of
an upper and a lower ring held
together by series of fixed vanes
called stay vanes and half the
number of guide vanes.
Guide vanes: from the speed
ring the water passes through
a series of guide vane or
wicket gates provided all
around the periphery of the
runner which allow the water
to enter without shock. The
guide vane are operated
either by means of a wheel or
automatically by a governor.
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10. Turbine runner
The runner of a Francis
turbine consists of a series
of curved vanes(about 16
to 24 in number) evenly
arranged around the
circumference in the
annular space between
two plates. The runner is
keyed to a shaft to drive
the generator. Its usually
made of cast iron for low
head and steel alloy for
higher heads.
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11. Draft tubeTurbine runner
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12. The water after passing through
the runner flows to the tail race
through a draft tube. A draft tube
is a pipe or passage of gradually
increasing cross sectional area
which connects the runner exit to
the tail race. The draft tube has 2
purposes :
1. It permits a negative or suction
head to be established at the
runner exit.
2. It converts a large proportion
of velocity energy rejected
from the runner into useful
pressure energy.(i.e., acts as a
recuperator of pressure
energy) Draft tube
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13. Blade geometry and characteristics
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15. Velocity triangle
At inlet triangle:
𝑈1 = velocity of the blade
at inlet
𝑉1 = absolute velocity of
entering water
𝑉𝑟1
= relative velocity of
entering water
𝑉𝑓1
= velocity of flow at
inlet
𝛼1 = guide blade angle
𝛽1 = vane angle
At outlet triangle:
𝑈2 = velocity of the
blade at outlet
𝑉𝑟2
= relative velocity of
leaving water
𝑉𝑓2
= 𝑉2 =velocity of
flow at outlet
𝛼2 = guide blade angle
𝛽2 = vane angle
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16. Velocity triangles of Francis Turbines at turbine runner blade inlet and outlet under
different operation conditions: (a) maximum wicket gate opening condition; (b) peak
efficiency condition; (c) minimum wicket gate opening condition. 16

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19. Guide vane at closed position
Operation of Guide Vanes
Guide vane at Design
Position = 12.21°
Guide vane at Max. open
Position = 18°
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20. The Francis Installation
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21. Work done and efficiencies
Work done per 𝑘𝑁 of water =
1
𝑔
𝑉𝑤. 𝑣 − 𝑉𝑤1
𝑣1 =
𝑉 𝑤.𝑣
𝑔
−
𝑉 𝑤1 𝑣1
𝑔
If there is no loss of energy then,
𝑉 𝑤.𝑣
𝑔
−
𝑉 𝑤1 𝑣1
𝑔
= 𝐻 −
𝑉1
2
2𝑔
If the discharge of the Francis turbine is radial (most of the cases) then,
Guide blade angle at exit 𝛽 = 90, 𝑉𝑤1
= 0, 𝑉1= 𝑉𝑓1
∴ work done per 𝑘𝑁 of water =
𝑉 𝑤.𝑣
𝑔
And work done
𝑉 𝑤.𝑣
𝑔
= 𝐻 −
𝑉1
2
2𝑔
= 𝐻 −
𝑉𝑓1
2
2𝑔
Hydraulic efficiency 𝜂ℎ =
𝑉 𝑤.𝑣
𝑔𝐻
Overall efficiency, 𝜂 𝑜 =
𝑃
𝑤𝑄𝐻
Where 𝑃 =power available at the turbine
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22. EFFICIENCY OF FRANCIS TURBINE
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23. Comparison with other turbines
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24. ADVANTAGES
1.It is a most widely used
turbine in world (about 70-80%).
2.Effective use of water pressure
as well as velocity.
3.It is American standard
turbine.
4.Very good efficiency(80-94%).
5. Can operate between a large
range of head heights (25 –
350m)
6. Medium acceptance of flow
variation
DISADVANTAGES
1.Low acceptance of head variation
2.Must be fully immersed in water and
enclosed in a pressure casing (difficult to
repair and reproduce)
3.Usually used only in large hydroelectric
systems
4.Due to its complex design and large
number of moving parts, maintenance and
repair is difficult and costly.
5.Guide vanes must be adjusted based on
current flow rate, so it needs to be manned
6. Cost is high.
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25. Recent Advancements:
 New types of designs are developed to reduce cost and complexity of
mechanism.
 Modified turbine include Inline Link less Francis Turbine, Cross-flow Turbine
etc.
 These new turbine require less space, simplified designs, less moving parts,
etc.
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