Francis Vs Kaplan Turbines: 14 Differences (With Comparison Chart)

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What Is Francis Turbine

Francis turbine is a type of water turbine that was developed by James B. Francis in Lowell, Massachussets United States Of America. Francis turbine is combines both the concepts of impulse and reaction turbine, whereby the blades rotate using both reaction and impulse force of water flowing through them. In this turbine waters enters the turbine radically and exits axially producing electricity more efficiently. This type of turbine is frequently used in the production of electricity in medium or large-scale hydro power stations.

Francis Turbine

What You Need To Know About Francis Turbine

  1. In Francis turbine, water enters the runner vanes radially and leaves axially hence it can be referred to as mixed flow turbine.
  2. In Francis turbine, the number of blades in the runner is generally between 16 and 24.
  3. Francis turbine requires relatively higher head conditions.
  4. Loss of energy due to friction of the blades is greater due to large number of blades.
  5. Efficiency of Francis turbine is less when compared to Kaplan turbine.
  6. The size of Francis turbine is relatively large when compared to Kaplan turbine.
  7. The disposition of shaft maybe vertical or horizontal as per requirement.
  8. The rotation speed (RPM) is relatively less than that of Kaplan turbine.
  9. In Francis turbine, Servomotor is located outside rotor shaft.
  10. Francis turbine runner vanes are not adjustable.
  11. Francis turbine requires medium flow rate of water.
  12. Francis turbine requires medium range of water head i.e it generally varies from 100-600 meters.
  13. It requires one servomotor for regulation of vanes with turning runner blades.
  14. It is used in irrigation water pumping sets to pump water from ground for irrigation.

What Is A Kaplan Turbine?

Kaplan turbine is a propeller-type water turbine with adjustable blades that was developed by an Australian Professor Viktor Kaplan. Kaplan turbine concept evolved from Francis turbine and it can also be referred to as Propeller turbine. Kaplan combined automatically adjustable propeller blades with automatically adjustable wicket gates to achieve efficiency over a wide range of flow and water level. Kaplan turbine is capable of working at low head and high flow rates very efficiently.

Kaplan turbine works on the principle of axial flow reaction. In axial flow turbines, the water flows through the runner along the direction parallel to the axis of rotation of the runner. The water at the inlet of the turbine possesses both kinetic energy as well as pressure energy for effective rotation of the blades in a hydro-power station. Kaplan turbines are common and widely used throughout the world in high-flow, low-head power production.

Kaplan Turbine

What You Need To Know About Kaplan Turbine

  1. In Kaplan turbine, water enters and leaves the turbine runner vane in axial direction.
  2. In Kaplan turbine, the number of blades in the runner is generally between 3 and 8.
  3. Kaplan turbines can operate under a wide range of head conditions.
  4. Loss of energy due to friction of the blades is less due to the small number of blades.
  5. Efficiency of Kaplan turbine is higher than Francis turbine. It is efficient over a wide range of water head and flow rate.
  6. Kaplan turbine is smaller and compact when compared to Francis turbine.
  7. The disposition of shaft is always in vertical direction because it is axial flow turbine.
  8. The rotation speed (RPM) is higher than that of the Francis turbine.
  9. In Kaplan turbine, Servomotors are located inside hollow shaft of turbine runner.
  10. Kaplan turbine runner vanes are adjustable.
  11. Kaplan turbine requires high flow rate of water.
  12. Kaplan turbine works on very low head, the requirement of head is generally 100 meters.
  13. It requires servomotors for regulation of the vanes with turning runner blades.
  14. It is used in small hydro-power plants to generate electricity.

Also Read: Difference Between Reaction Turbine And Impulse Turbine

Difference Between Francis And Kaplan Turbines In Tabular

BASIS OF COMPARISON FRANCIS TURBINE KAPLAN TURBINE
Description In Francis turbine, water enters the runner vanes radially and leaves axially hence it can be referred to as mixed flow turbine.   In Kaplan turbine, water enters and leaves the turbine runner vane in axial direction.  
Number Of Blade The number of blades in the runner is generally between 16 and 24.   The number of blades in the runner is generally between 3 and 8.
Head Condition Francis turbine requires relatively higher head conditions.   Kaplan turbines can operate under a wide range of head conditions.  
Loss Of Energy Loss of energy due to friction of the blades is greater due to large number of blades.   Loss of energy due to friction of the blades is less due to the small number of blades.  
Efficiency Efficiency of Francis turbine is less when compared to Kaplan turbine.   Efficiency of Kaplan turbine is higher than Francis turbine. It is efficient over a wide range of water head and flow rate.  
Size The size of Francis turbine is relatively large when compared to Kaplan turbine.   Kaplan turbine is smaller and compact when compared to Francis turbine.  
Disposition Of Shaft The disposition of shaft maybe vertical or horizontal as per requirement.   The disposition of shaft is always in vertical direction because it is axial flow turbine.  
Rotation Speed The rotation speed (RPM) is relatively less than that of Kaplan turbine.   The rotation speed (RPM) is higher than that of the Francis turbine.  
Servomotor Location In Francis turbine, Servomotor is located outside rotor shaft.   In Kaplan turbine, Servomotors are located inside hollow shaft of turbine runner.  
Runner Francis turbine runner vanes are not adjustable.   Kaplan turbine runner vanes are adjustable.  
Flow Rate Of Water Francis turbine requires medium flow rate of water.   Kaplan turbine requires high flow rate of water.  
Water Head Size Francis turbine requires medium range of water head i.e it generally varies from 100-600 meters.   Kaplan turbine works on very low head, the requirement of head is generally 100 meters.  
Servomotor Requirement It requires one servomotor for regulation of vanes with turning runner blades.   It requires servomotors for regulation of the vanes with turning runner blades.  
Application It is used in irrigation water pumping sets to pump water from ground for irrigation.   It is used in small hydro-power plants to generate electricity.  

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