This document provides information about a group project to design an impulse turbine. The group leader is Abdul Jabbar and the other 7 group members are listed. It then provides details about turbines in general and impulse turbines specifically. It discusses the classification, working principle, parts, and efficiency of impulse turbines. It also compares impulse turbines to reaction turbines and lists the advantages and disadvantages of impulse turbines.

2. PROJECT TITLE
IMPULSE TURBINE

3. GROUP LEADER ABDUL JABBAR
& GROUP MEMBERS
NAME
• ABDUL JABBAR
• NISAR AHMED
• SHAMS ULLAH
• NADIR AHMED
• SAIF UDDIN
• RIAZ AHMED
• ALI HASSAN
• ANEESA ANWER
ROLL NUMBER
• 16CE02
• 16CE04
• 16CE06
• 16CE08
• 16CE12
• 16CE14
• 16CE76
• 16CE16

4. What Is TURBINE
• Turbine is the mechanical equipment which converts the pressure
energy into kinetic energy.
• later on, its kinetic energy of turbine is used to generate electric
power through generators.
• Basically work done by the turbine is calculated by the difference of
outlet and inlet enthalphy of the flow medium.
• Classification of turbine based on flow medium
• Steam turbine
• Gas turbine
• Hydraulic turbine

5. Hydraulic Turbines
Hydraulic Turbines have a row of blades fitted to the rotating shaft or a
rotating plate. Flowing liquid, mostly water, when pass through the
Hydraulic Turbine it strikes the blades of the turbine and makes the
shaft rotate. While flowing through the Hydraulic Turbine the velocity
and pressure of the liquid reduce, these result in the development of
torque and rotation of the turbine shaft.

6. • Classification of Hydraulic Turbines: Based on flow path
• Water can pass through the Hydraulic Turbines in different flow paths.
Based on the flow path of the liquid Hydraulic Turbines can be categorized
into three types.
• Axial Flow Hydraulic Turbines:
• This category of Hydraulic Turbines has the flow path of the liquid mainly
parallel to the axis of rotation. Kaplan Turbines has liquid flow mainly in
axial direction.

7. • Radial Flow Hydraulic Turbines:
• Such Hydraulic Turbines has the liquid flowing mainly in a plane
perpendicular to the axis of rotation.
• Mixed Flow Hydraulic Turbines: For most of the Hydraulic Turbines
used there is a significant component of both axial and radial flows.
Such types of Hydraulic Turbines are called as Mixed Flow Turbines.
Francis Turbine is an example of mixed flow type, in Francis Turbine
water enters in radial direction and exits in axial direction

8. impulse turbine
• An impulse turbine is a turbine that is driven by high velocity jets of
water or steam from a nozzle directed on to vanes or buckets
attached to a wheel. The resulting impulse (as described by Newton's
second law of motion) spins the turbine and removes kinetic energy
from the fluid flow.

9. • Before reaching the turbine the fluid's pressure head is changed to
velocity head by accelerating the fluid through a nozzle. This
preparation of the fluid jet means that no pressure casement is
needed around an impulse turbine.
• Most types of turbine exploit the principles of both impulse turbines
and reaction turbines However, a few, such as the Pelton turbine use
the impulse concept exclusively

10. Main types of impulse turbine
• Pelton
A Pelton turbine has one or more free jets discharging water into an
aerated space and impinging on the buckets of a runner. Draft tubes
are not required for impulse turbine since the runner must be
located above the maximum tailwater to permit operation at
atmospheric pressure.

11. • Cross-flow turbine
• A cross-flow turbine is drum-shaped and uses an elongated,
rectangular-section nozzle directed against curved vanes on a
cylindrically shaped runner. It resembles a "squirrel cage" blower. The
cross-flow turbine allows the water to flow through the blades twice.
The first pass is when the water flows from the outside of the blades
to the inside; the second pass is from the inside back out. A guide
vane at the entrance to the turbine directs the flow to a limited
portion of the runner. The cross-flow was developed to
accommodate larger water flows and lower heads than the Pelton.

12. Parts and Their Functions of Pelton Turbine
• Different parts and their functions of Pelton turbine are as follows.
• Nozzle and Flow Regulating Arrangement
• Runner and Buckets
• Casing
• Braking Jet

13. Nozzle and Flow Regulating Arrangement
• The water from source is transferred through penstock to which end
a nozzle is provided. Using this nozzle the high speed water jet can be
formed. To control the water jet from nozzle, a movable needle spear
is arranged inside the nozzle.
•
The spear will move backward and forward in axial direction. When it
is moved forward the flow will reduce or stopped and when it is
moved backward the flow will increase.

14. .Runner and Buckets
• A Pelton turbine consists of a runner, which is a circular disc on the
periphery of which a number of buckets are mounted with equal
spacing between them. The buckets mounted are either double
hemispherical or double ellipsoidal shaped.
• A dividing wall called splitter is provided for each bucket which
separates the bucket into two equal parts. The buckets are generally
made of cast iron or stainless steel or bronze depending upon the
head of inlet of Pelton turbine.

15. .Casing
• The whole arrangement of runner and buckets, inlet and braking jets are
covered by the Casing. Casing of Pelton turbine does not perform any
hydraulic actions but prevents the splashing of water while working and
also helps the water to discharge to the tail race.

16. .Braking Jet
• Braking jet is used to stop the running wheel when it is not working.
This situation arises when the nozzle inlet is closed with the help of
spear then the water jet is stopped on the buckets. But Due to
inertia, the runner will not stop revolving even after complete closure
of inlet nozzle.
• To stop this, a brake nozzle is provided as shown in figure 1. The
brake nozzle directs the jet of water on the back of buckets to stop
the wheel. The jet directed by brake nozzle is called braking jet.

19. WORKING PRINCIPE OF IMPULSE TURBINE
• Impulse turbine works on the basic principle of impulse. When the
jet of water strikes at the turbine blade with full of its speed, it
generates a large force which used to rotate the turbine.
• The force depends on the time interval and velocity of jet strikes the
blades. This turbine used to rotate the generator, which produces
electric power.

21. • The term impulse means sudden force act to bring desire change. It
denotes as product of force and time interval for which it acts. The
impulse shows the total result of applying force. Impulse turbine
works on the same principle. It is mostly used at high heads.
Impulse = Ft
You have force multiplied by time, so the unit is the Newton-second.

22. Working of impulse turbine
As we discussed impulse turbine works on basic principle of impulse.
Its working can be describe in following points.
• High pressure water flow form dam (high head) to nozzle (low
head).
• This water flows through divergent nozzle where it’s all pressure
energy change into kinetic energy. It forms a water jet.

23. • The water jet strikes the blade at high speed which rotates the rotor.
• It transfers all kinetic energy of water to the rotor, which further
use to rotate the generator.
• After transferring energy, water flows to the tail race.
• This process run continuously until sufficient power generates.

24. DIFFERENCE BETWEEN IMPULSE AND REACTION TURBINES
• The term impulse and reaction denote the basic type of turbine. The basic
and main difference between impulse and reaction turbine is that there is
pressure change in the fluid as it passes through runner of reaction turbine
while in impulse turbine there is no pressure change in the runner.
• In the impulse turbine first all pressure energy of water converts into the
kinetic energy through a nozzle and generate a high speed jet of water. This
water jet strikes the blade of turbine and rotates it. In the reaction turbine
there is pressure change of water when it passes through the rotor of
turbine. So it uses kinetic energy as well as pressure energy to rotate the
turbine. Due to this it is known as reaction turbine.
•

26. Difference Between Impulse And Reaction Turbine
Impulse Turbine
• 1. In impulse turbine only
kinetic energy is used to
rotate the turbine.
2. In this turbine water flow
through the nozzle and
strike the blades of turbine.
Reaction Turbine
• 1. In reaction turbine both
kinetic and pressure energy
is used to rotate the turbine.
• 2. In this turbine water is
guided by the guide blades
to flow over the turbine.

27. Impulse turbine
• 3. All pressure energy of
water converted into kinetic
energy before striking the
vanes.
• 4. The pressure of the water
remains unchanged and is
equal to atmospheric
pressure during process.
Reaction turbine
• 3. In reaction turbine, there is
no change in pressure energy of
water before striking.
• 4. The pressure of water is
reducing after passing through
vanes.
•

28. Impulse turbine
• 5. In impulse turbine casing has
no hydraulic
function to perform because
the jet is at atmospheric
pressure. This casing serves only
to prevent splashing of water.
Reaction turbine
• 5. Casing is absolutely necessary
because the pressure at inlet of
the turbine is much higher than
the pressure at outlet. It is
sealed from atmospheric
pressure.

29. Impulse turbine
• 6. Water may admitted over a
part of circumference or over
the whole circumference of the
wheel of turbine.
• 7. This turbine is most suitable
for large head and lower flow
rate. Pelton wheel is the
example of this turbine.
Reaction turbine
• 5. Water may admitted over a
part of circumference or over
the whole circumference of the
wheel of turbine.
• 7. This turbine is best suited for
higher flow rate and lower head
situation.

30. Advantages & Disadvantages Of Impulse Turbine
Advantage:
• 1. It can works at low discharge or at low flow rates.
• 2. This turbine has high efficiency.
• 3. Impulse turbine is flexible according to the load condition. At
higher load more than one nozzle are used.
• 4. They work at atmospheric pressure so no problem of leakage.
• 5. It is easy to assemble.
•

31. • Disadvantages:
• 1. Large size compare to others.
• 2. Efficiency decreases with time.
• 3. It required high head witch is hard to control.
• 4. It is costly to install.

32. Efficiency of impulse turbine
• To measure the efficiency of Impulse Turbine, we can use following
three types of efficiency.
• Basically, in engineering, efficiency is the ratio of work done by the
turbine to the energy supplied.
• 1: Hydraulic Efficiency
• It is the ratio of work done on the wheel to the energy of the jet.

33. • 2 Mechanical Efficiency
In practical, it is observed that all the energy supplied to the wheel
does not come out as the useful work.
• Some energy is wasted to overcome the friction of bearing and other
moving parts.
• Hence keeping this point in mind, the mechanical efficiency is the
ratio of actual work available at the turbine to the energy imparted to
the wheel.

34. • 3 Overall Efficiency
• It is the ratio of actual power produced by the turbine to
the energy actually supplied by the turbine.
• With this efficiency, you can measure the performance of the
turbine.

35. Design Aspects Of Impulse Turbine
• Following are the aspects to be considered while designing the
Pelton wheel turbine.
• Velocity of jet
• Velocity of wheel
• Angle of deflection of jet
• Mean diameter of the wheel
• Jet ratio
• Bucket dimensions
• Number of jets
• Number of buckets

36. • 1.Velocity of Jet
• The velocity of the jet at inlet is given by
• V=Cv√2gH
• Where Cv = co-efficient of velocity =0.98 or 0.99.
• H= Net head on turbine.
• 2.Velocity of Wheel
• The velocity of wheel (u) is given by
• U=ф√2gH
• Where, ф = speed ratio = 0.43 to 0.48

37. • 3.Angle of Deflection of Jet
• The angle of deflection of jet after striking the buckets is taken
as 165o if no deflection angle is given.
• 4.Mean Diameter of The Wheel
• The mean diameter or the pitch diameter D of the pelton turbine is
given by
D=60u÷πN

38. • 5.Jet Ratio
• It is defined as the ratio of the pitch diameter (D) of the pelton
turbine to the diameter of the jet (d). It is denoted by m and is given
as
• m = D/d
• Jet ratio(m) is lies between 11 to 16 for maximum hydraulic
efficiency. however, In most of the cases it is taken as 12.
• 6.Bucket Dimensions
• Buckets dimensions are designed in such a way that its breadth
should be 3 to 4 times of diameter of jet, length should be 2 to 3
times of diameter of jet and thickness should be 0.8 to 1.2 times the
diameter of jet.

39. • 7.Number of Jets
• It is obtained by dividing the total rate of flow through the turbine by
the rate of flow of water through a single jet.
• In general, Number of jets are limited to two in case of vertical
runner and six in case of horizontal runner.
• 8.Number of Buckets
• The number of buckets (z) on a runner is given by
• Z=15+0.5m and m=D/d
• Where, D = Pitch diamater
• d = Diameter of Jet
• m = jet ratio