1. Introduction of Kaplan and Propeller Turbines
Kaplan and Propeller turbines are axial flow reaction turbines used in hydroelectric power plants. In both turbines, water flows parallel to the axis of rotation of the runner.
- Used for low head and high discharge
- Widely applied in river-based hydropower plants
Key idea:
Both are similar in design, but differ in blade adjustability
Table of Contents
2. Kaplan Turbine
Overview
A Kaplan turbine is an axial flow reaction turbine with adjustable runner blades. It is highly efficient under varying load conditions.
Construction
4
Main components:
- Runner with adjustable blades
- Hub (blade control mechanism)
- Guide vanes (wicket gates)
- Spiral casing
- Draft tube
- Shaft
Working Principle
- Water enters through the spiral casing
- Guide vanes control the flow direction
- Water flows axially through the runner
- Adjustable blades change angle according to flow
- Maximum energy transfer occurs
- Water exits through the draft tube
Features
- Adjustable runner blades
- High efficiency (up to 90%)
- Works efficiently at varying loads
- Suitable for low head (2–40 m)
Advantages
- High efficiency over wide load range
- Flexible operation
- Suitable for fluctuating water flow
Disadvantages
- Complex design
- High initial cost
- Maintenance is difficult
3. Propeller Turbine
Overview
A propeller turbine is also an axial flow reaction turbine, but its runner blades are fixed (non-adjustable).
Construction
4
Main components:
- Runner with fixed blades
- Guide vanes
- Casing
- Draft tube
- Shaft
Working Principle
- Water flows axially through the runner
- Fixed blades receive energy from flowing water
- Runner rotates and produces mechanical power
- Water leaves through the draft tube
Features
- Simple construction
- Fixed blade angle
- Suitable for constant load conditions
- Works at low head and high discharge
Advantages
- Simple design
- Lower cost than Kaplan
- Easy maintenance
Disadvantages
- Lower efficiency at varying loads
- Not suitable for fluctuating flow conditions
4. Difference Between Kaplan and Propeller Turbine
| Feature | Kaplan Turbine | Propeller Turbine |
|---|---|---|
| Blade Type | Adjustable | Fixed |
| Efficiency | High at all loads | High at constant load |
| Complexity | Complex | Simple |
| Cost | High | Lower |
| Application | Variable flow | Constant flow |
5. Similarities
- Both are reaction turbines
- Both operate under low head conditions
- Flow is axial
- Use draft tubes
- Installed in hydroelectric plants
6. Applications
- River power plants
- Tidal power stations
- Irrigation canals
- Low-head hydroelectric projects