Hydraulic turbines

1. HYDRAULIC
TURBINES

2. o Hydraulic Machines
It is defined as those machines which convert either
hydraulic energy into mechanical energy (i.e. turbines) or
mechanical energy into hydraulic energy (i.e. pumps).
o Turbines
It is defined as the hydraulic machines which converts
hydraulic energy into mechanical energy.
o Head of Turbines
1. Gross Head (𝑯 𝒈)
2. Net Head (H)
3. Head loss (𝒉 𝒇)

3. o Power of Turbines
1. Water Power (WP)
2. Runner Power (RP)
3. Shaft Power (SP)
o Efficiencies of Turbines
1. Hydraulic Efficiency (η 𝒉) =
𝑹.𝑷.
𝑾.𝑷.
2. Mechanical Efficiency (η 𝒎) =
𝑺.𝑷.
𝑹.𝑷.
3. Overall Efficiency (η 𝒐) =
𝑺.𝑷.
𝑾.𝑷.
4. Volumetric Efficiency (η 𝒐) =
𝑸 𝟏
𝑸
𝑄1= Amount of water striking per sec
Q = Amount of water supplied per sec by jet

4. CLASSIFICATION OF HYDRAULIC TURBINES
1. According to the type of energy at inlet
(a) Impulse turbine (ex – Pelton wheel)
(b) Reaction turbine (ex – Francis turbine, Kaplan turbine etc)
2. According to the direction of flow through runner
(a) Tangential flow turbine (ex – Pelton wheel)
(b) Radial flow turbine (ex – Francis turbine)
(c) Axial flow turbine (ex –Kaplan turbine)
(d) Mixed flow turbine (ex – ModernFrancis)
3. According to the head at the inlet of the turbine
(a) High head turbine (more than 250 m. ex – Pelton wheel)
(b) Medium head turbine (60 m to 250 m. ex – Francis turbine)
(c) Low head turbine (less than 60 m. ex –Kaplan turbine)
4. According to the specific speed of the turbine
(a) High specific speed turbine
(less than 30 single jet, 30 to 50 multi jet pelton wheel)
(b) Medium specific speed turbine (50 to 260 Francis turbine)
(c) High specific speed turbine (260 to 860 Kaplan turbine)

5. PELTON WHEEL (OR TURBINE)
 Components of Pelton Wheel
1. Nozzle and Flow Regulating Arrangement (Spear ) 3. Casing and
2. Runner and Buckets 4. Breaking Jet

6. PELTON WHEEL (OR TURBINE)
Shape of bucket

8. REACTION TURBINE
 In reaction turbine, water at the inlet of the turbine possesses kinetic energy
as well as pressure energy.
 As water flows through runner, a part of pressure energy goes on changing
into kinetic energy.
 Thus the water through runner is under pressure and the runner is completely
enclosed in an air-tight casing.
 Casing and the runner is always full of water.
Radial Flow Reaction turbine
 In radial flow reaction turbine the water flows in the radial direction.
 If the water flows from outward to inwards through the runner, the turbine is
known as inward radial flow turbine.
 If the water flows from inward to outwards through the runner, the turbine is
known as outward radial flow turbine.

9. FRANCIS TURBINE
Components of Francis turbine
1. Scroll casing
2. Guide mechanism
3. Runner
4. Draft tube

11. KAPLAN TURBINE
Components of Francis turbine
1. Scroll casing 2. Guide mechanism
3. Hub with vanes or runner 4. Draft tube

12. GOVERNING OF PELTON WHEEL

13. GOVERNING OF FRANCIS TURBINE

14. CHARACTERISTIC CURVES OF HYDRAULIC
TURBINES
 The turbines are generally designed to work at particular designed
conditions. But often the turbines are required to work at different
conditions. Therefore it is essential to determine the exact behavior of
the turbines under the varying conditions.
 “Characteristic curves of a hydraulic turbine are the curves, with the
help of which the exact behavior and performance of the turbine under
different working conditions can be known.”
 The following are the important characteristic curves for a hydraulic
turbine:
1. Main Characteristic Curves or Constant Head Curves
2. Operating Characteristic Curves or Constant Speed Curves
3. Constant Efficiency Curves

15. 1. MAIN CHARACTERISTIC CURVES
 Main characteristic curves are obtained by maintaining a constant
head and a constant gate opening on the turbine.
 The characteristic curves drawn are:
a) Unit discharge vs unit speed
b) Unit power vs unit speed
c) Overall efficiency vs unit speed
oUnit discharge vs unit speed

16. oUnit power vs unit speed
oOverall efficiency vs unit speed

17. 2. OPERATING CHARACTERISTIC CURVES

18. 3. CONSTANT EFFICIENCY CURVES

19. CENTRIFUGAL PUMP
 Main parts of a
centrifugal pump are:
1. Impeller
2. Casing
3. Suction pipe
4. Delivery pipe

20.  Types of Casing
1) Volute casing
2) Vortex casing
3) Casing with Guide blades

21. CHARACTERISTIC CURVES OF HYDRAULIC
PUMPS
 Characteristic curves of centrifugal pumps are defined those curves
which are plotted from the results of a number of tests on the
centrifugal pump. These curves are necessary to predict the behavior
and performance of the pump when the pump is working under
different flow rate, head and speed.
 The followings are the important characteristic curves for pumps:
1. Main Characteristic Curves
2. Operating Characteristic Curves
3. Constant Efficiency Curves

22. 1. Main Characteristic Curves

23. 2. Operating Characteristic Curves

24. 3. Constant Efficiency Curves