Introduction to Hydraulic Turbine free study notes for Diploma / BTech.

1. What is a Hydraulic Turbine?

A hydraulic turbine is a rotary machine that converts the energy of flowing or falling water into mechanical energy, which is then usually converted into electrical energy using a generator.

It is one of the most important components in a hydroelectric power plant.

2. Working Principle of Hydraulic Turbine

Hydraulic turbines work on the principle of conservation of energy and Newton’s laws of motion.

• Water at a certain head (height) possesses potential energy
• When it flows, it gains kinetic energy
• This energy is transferred to the turbine runner blades
• The runner rotates, producing mechanical energy

In simple words:
Water energy → Mechanical energy → Electrical energy

3. Energy Conversion in Turbine

The energy transformation in a hydraulic turbine involves:

1. Potential Energy → due to height of water
2. Kinetic Energy → due to velocity of water
3. Mechanical Energy → rotation of turbine shaft
4. Electrical Energy → via generator

4. Main Components of Hydraulic Turbine

A hydraulic turbine mainly consists of:

5. Classification of Hydraulic Turbines

Hydraulic turbines can be classified based on different criteria:

(1) Based on Energy at Inlet

• Impulse Turbine
  • Uses only kinetic energy
  • Example: Pelton wheel
• Reaction Turbine
  • Uses both pressure and kinetic energy
  • Example: Francis turbine, Kaplan turbine

(2) Based on Direction of Flow

• Tangential Flow Turbine (Pelton)
• Radial Flow Turbine (Francis – inward/outward)
• Axial Flow Turbine (Kaplan)
• Mixed Flow Turbine (Francis)

(3) Based on Head

• High Head Turbine (>250 m)
• Medium Head Turbine (60–250 m)
• Low Head Turbine (<60 m)

(4) Based on Specific Speed

• Low specific speed → Pelton
• Medium → Francis
• High → Kaplan

6. Types of Hydraulic Turbines

(a) Pelton Turbine (Impulse)

4

• Used for high head, low flow
• Water jet strikes buckets
• Simple design, high efficiency

(b) Francis Turbine (Reaction)

4

• Used for medium head
• Water flows radially then axially
• Most widely used turbine

(c) Kaplan Turbine (Reaction)

4

• Used for low head, high flow
• Propeller-type blades (adjustable)
• High efficiency for varying loads

7. Important Terminology

• Head (H): Height of water above turbine
• Discharge (Q): Flow rate of water
• Efficiency (η): Ratio of output power to input power
• Specific Speed (Ns): Determines type of turbine suitable

8. Applications of Hydraulic Turbines

• Hydroelectric power generation
• Irrigation systems
• Pumped storage plants
• Renewable energy systems

9. Advantages

• Renewable and eco-friendly
• High efficiency (up to 90%)
• Low operating cost
• Long service life

10. Disadvantages

• High initial cost
• Depends on water availability
• Environmental impact (ecosystem disturbance)
• Requires large infrastructure (dams)

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