Hydraulic Turbines: Introduction and Classification

Hydraulic turbines are Machines which convert hydraulic energy in to mechanical energy. Uses the potential energyand kinetic energy of water and rotate the rotor by dynamic action of water.

Classification of Hydraulic turbines:

1) Based on type of energy at inlet to the turbine:

Impulse Turbine : The energy is in the form of kinetic form. e.g: Pelton wheel, Turbo wheel.
Reaction Turbine : The energy is in both Kinetic and Pressure form. e.g: Tubular, Bulb, Propellar, Francis turbine.

2) Based on direction of flow of water through the runner:

Tangential flow: water flows in a direction tangential to path of rotational, i.e. Perpendicular to both axial and radial directions.
Radial outward flow e.g : Forneyron turbine.
Axial flow : Water flows parallel to the axis of the turbine. e.g: Girard, Jonval, Kalpan turbine.
Mixed flow : Water enters radially at outer periphery and leaves axially. e.g : Modern Francis turbine.

3) Based on the head under which turbine works:

High head, impulse turbine. e.g : Pelton turbine.
Medium head,reaction turbine. e.g : Francis turbine.
Low head, reaction turbine. e.g : Kaplan turbine, propeller turbine.

4) Based on the specific speed of the turbine:

Low specific speed, impulse turbine. e.g : Pelton wheel.
Medium specific speed, reaction turbine. e.g : Francis wheel.
High specific speed, reaction turbine. e.g : Kaplan and Propeller turbine.

5) Based on the name of the originator:

Impulse turbine – Pelton wheel, Girard, Banki turbine.
Reaction turbine – Forneyron, Jonval, Francis, Dubs, Deriaze, Thomson kalpan, Barker, Moody, Nagler, Bell.

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