Jet propulsion means the propulsion or movement of the bodies such as ships, aircrafts, rocket etc. with the help of jet. It is well known from Newton’s Law that to change momentum of fluid, a force is required. Similarly, when momentum of fluid is changed, a force is generated. This principle is made use in hydraulic turbine.

1. Unit-1
Hydraulic machines
Jet Propulsion
&
Pelton Turbines
From
Ankit Saxena

2. Jet Propulsion
Jet propulsion means the propulsion or movement of the bodies
such as ships, aircrafts, rocket etc. with the help of jet.
There are following cases which are used
(a) Jet propulsion of a tank to which orifice is
fitted, and
(b)Jet propulsion of ships.

3. (a)Jet propulsion of a tank with an
Orifice

5. Condition for maximum efficiency and
expression for maximum efficiency

6. (b) Jet propulsion of Ships
A ship is driven through water, A jet of water is discharged at the
back also called stern of the ship, exerts a propulsive force on
the ship.
The water from the surrounding media is taken by following two
ways:
1) Through inlet orifice which are at right angles to the
direction of the motion of the ship, and
2) Through the inlet orifices, which are facing the direction of
motion of the ship.

7. (1) Through inlet orifice which are at right angles to the direction
of the motion of the ship

8. (2) Through the inlet orifices, which are facing the
direction of motion of the ship

10. Turbines
• It is well known from Newton’s Law that to change momentum
of fluid, a force is required. Similarly, when momentum of fluid
is changed, a force is generated. This principle is made use in
hydraulic turbine.
• A hydraulic turbine uses potential energy and kinetic energy of
water and converts it into usable mechanical energy. The
mechanical energy made available at the turbine shaft is used
to run an electric power generator which is directly coupled to
the turbine shaft.
• The electric power which is obtained from the hydraulic energy
is known as Hydroelectric energy. Hydraulic turbines belong to
the category of roto- dynamic machinery.

11. • The main components of a hydroelectric system may be
classified into two groups:
• The hydraulic system components that include the turbine, the
associated conduits-like penstocks, tunnel and surge tank-and
its control system, and
• The electric system components formed by the synchronous
generator and its control system.

12. Layout of a Hydro-Electric Power Plant

14. History of Hydraulic Turbines
• Water wheels – China and Egypt – thousands of years ago.
• Reaction runner – J A Segnar – 1950.
• Euler turbine theory – Leonard Euler – valid till today
• Turbine is a designation that was introduced in 1824 in a dissertation of the French
engineer Burdin.
• Fourneyron designed a radial turbine and put to operation the first real turbine
• in 1827 – power 20-30 kW and runner diameter of 500 mm.
• Henschel and Jonval in 1840 independently developed turbine with axial water flow
through it. They were the first ones to apply draft tube and in that way to utilize the
water head between runner outlet and tail water level.
• Francis in 1849 developed the radial turbine, named Francis turbine.
• In 1870 professor Fink introduced an important improvement in Francis turbine by
making the guide vanes turning on a pivot in order to regulate the flow discharge.
• In 1890 American engineer Pelton developed impulse turbine, named Pelton Turbine
• In 1913 Kaplan designed a propeller turbine, named Kaplan turbine, Subsequent
developments were made on Francis, Pelton and Kaplan turbines.

15. Turbine
Tangential flow
(Pelton wheel)
Axial flow (Kaplan
turbine)
Mixed: Radial and
axial (Modern
francis turbine)
Outward radial
flow (Fourneyron
turbine)
Inward radial flow
(Old francis
turbine)
Classification of Hydraulic Turbines

16. Hydraulic turbines are generally classified as
A) According to hydraulic action/ Type of energy available at
inlet
(a) Impulse turbine (b) Reaction turbine
• The flow energy to the impulse turbines is completely
converted to kinetic energy before transformation in the
runner.
• The impulse forces being transferred by the direction
changes of the flow velocity vectors when passing the
buckets create the energy converted to mechanical
energy on the turbine shaft.
• The flow enters the runner from jets spaced around the
rim of the runners. The jet hits momentarily only a part of
the circumference of the runner.

17. • In the reaction turbines two effects cause the energy
transfer from the flow to the mechanical energy on the
turbine shaft:
• Firstly, it follows from a drop in pressure from inlet to
outlet of the runner. This is denoted as the reaction part
of the energy conversion.
• Secondly, the changes in the directions of the flow
velocity vectors through the runner blade channels
transfer impulse forces. This is denoted as the impulse
part of the energy conversion.
• The pressure from inlet to outlet of the runners is
obtained because the drop runners are completely filled
with water.

19. B) According to the direction of flow through runner:
• Tangential flow turbines: In this type of turbines, the water
strikes the runner in the direction of tangent to the wheel.
Example: Pelton wheel turbine.
• Radial flow turbines: In this type of turbines, the water strikes
in the radial direction. Accordingly, it is further classified as,
a. Inward flow turbine: The flow is inward from periphery to the centre
(centripetal type). Example: old Francis turbine.
b. Outward flow turbine: The flow is outward from the centre to periphery
(centrifugal type). Example: Fourneyron turbine
• Axial flow turbine: The flow of water is in the direction parallel
to the axis of the shaft. Example: Kaplan turbine and propeller
turbine.
• Mixed flow turbine: The water enters the runner in the radial
direction and leaves in axial direction. Example: Modern
Francis turbine.

20. C) According to the head at inlet of turbine:
• High head turbine: In this type of turbines, the net head varies from
150m to 2000m or even more, and these turbines require a small
quantity of water. Example: Pelton wheel turbine.
• Medium head turbine: The net head varies from 30m to 150m, and
also these turbines require moderate quantity of water. Example:
Francis turbine.
• Low head turbine: The net head is less than 30m and also these
turbines require large quantity of water. Example: Kaplan turbine.
D) According to the specific speed of the turbine
• Low specific speed turbine: The specific speed is less than 50.
(varying from 10 to 35 for single jet and up to 50 for double jet )
Example: Pelton wheel turbine.
• Medium specific turbine: The specific speed is varies from 50 to 250.
Example: Francis turbine.
• High specific turbine: the specific speed is more than 250. Example:
Kaplan turbine.

21. Difference between Impulse and Reaction turbine

22. Basic definitions

23. Gross head (Hg): Difference b/w the head race level and tail
race level when no water is flowing. Therefore it is also called
static head or total head.
Net head or effective head (H): Head available at the
inlet of the turbine. It is also called effective head. When water
is flowing from reservoir to turbine, considering the loss due to
friction alone, the net head is given by
H= Hg− hf
For reaction turbine, the net head is given as
H= (Total energy at exit from penstock)-(Total energy at exit from
the draft tube)
= 2 2
2 2penstock drafttube
p pv vZ Z
g g g g 

   
      
   

24. Tangential flow impulse turbine/ Pelton Turbine
Constructional details of Pelton turbine
1) Nozzle with Flow regulating mechanism

25. 2) Casing: casing has no hydraulic function to perform its only function
is to prevent splash of water, guide the water to the tail race, and
provide safety against accidents.
3) Runner and Buckets

26. Thank you