Correct Answer - Option 3 : Axial flow reaction turbine
A Kaplan turbine is basically a propeller with adjustable blades inside a tube. It is an axial-flow turbine, which means that the flow direction does not change as it crosses the rotor.
Classification of the turbine-based on the energy available at the inlet:
i) Reaction Turbine: Turbine for which both pressure energy and kinetic energy is available at the inlet is a reaction turbine.
E.g. Francis Turbine, Kaplan Turbine and Propeller Turbine.
They are useful for low head and high discharge.
ii) Impulse Turbine: Turbine for which only kinetic energy is available at the inlet is an impulse turbine.
E.g. Pelton Turbine and Turgo Impulse Turbine.
They are useful for high head and low discharge.
Flow
|
Energy
|
Head
|
Specific speed
|
Example
|
Tangential
|
Impulse
|
High head
(300 m and above)
|
Low
(0 – 60 RPM)
|
Pelton Wheel turbine
|
Radial
|
Reaction
|
Medium
(30 m to 300 m)
|
Medium
(60 – 300) RPM
|
Francis turbine
|
Axial
|
Reaction
|
Low
(less than 30 m)
|
High
|
|
(300 – 600) RPM
|
Kaplan turbine
|
(600 – 1000) RPM
|