Hydraulic Turbines and Its Classifications

Hydraulic machines are defined as machines which converts the hydraulic energy into the mechanical energy or mechanical energy into the hydraulic energy. The hydraulic machines are which converts the hydraulic energy into the mechanical energy is known as turbines.

Sponsored Links:

Classification of the hydraulic turbines:

According to the basis of energy intake

  • Impulse turbine
  • Reaction turbine

According to the direction of flow of water

  • Axial flow turbines
  • Radial flow turbines
  • Tangential flow turbines
  • Mixed flow turbines
Sponsored Links:

According to the specific speed of the turbine

  • Low specific speed turbine
  • Medium specific speed turbine
  • High specific speed turbine

According to the water head and quality of water available

  • High head and small quantity of water flow
  • Medium head and medium flow rate
  • Low head and large flow rate

According to the basis of energy intake

Sponsored Links:

Impulse turbine:

The total head of the entering fluid is changed into a great velocity head at the exit of the supply nozzle. So the entire available energy of water must be converted into the kinetic energy. There are various types of impulse turbines designs that are available, but the easiest one is Pelton wheel turbine. The Pelton wheel turbine is the most efficient type of the turbine when operated with large head rate and lower flow rate.

Different types of the impulse turbines are Turgo Impulse Turbine, Gurard Turbine, Pelton Wheel Banki Turbine and Jonval Turbine.

Reaction Turbine:

Reaction turbines are suitable for lower heads and higher flow rate situations. In the type of the turbines the revolution rotor or runner is partially due to the impulse action and moderately due to the change in pressure over the runner blade. So it is known as the impulse turbine. In the reaction turbine the penstock tube feeds water to a row of immovable blades through casting. The fixed plates in the turbine are used to convert the pressure energy into the kinetic energy before the water enters into the turbine. The water entering into the runner must have both the pressure energy and the kinetic energy in the reaction turbine. The out flowing water must have still loss of some energy. Due to the flow of the fluid from the head to the tail section the casing is necessary to enclose the turbine.  The reaction turbines are mainly suitable for the medium heads to low heads and also for high range flow devices.

Different types of the reaction turbines are Propeller Turbine, Francis Turbine, Kaplan Turbine, Fournryron Turbine and Thomson Turbine.

Difference of impulse turbine and reaction turbine:

S.No Impulse turbine Reaction turbine
1 By using nozzle before entering to the turbine runner the potential energy is converted into the kinetic energy Before fluid entering in to the turbine the fluid energy must be converted into the kinetic energy
2 Without loss flow regulation is possible With loss flow regulation is possible
3 Above the tail race  unit is installed Below the tailrace the unit is kept entirely submerged in water
4 Blades are only the action when they are infront of the nozzle At the time blades are in action

According to the direction of flow of water

Axial flow turbines

In the axial flow turbine the flow of the water is in all the directions is parallel to the shaft.

Example of Axial flow turbine:

Jonval turbine, Propeller turbine and Kaplan turbine

Radial flow turbines

In the radial flow turbines the water strikes in the radial direction. They are divided into two types they are Inward flow turbine and Outward flow turbine.

Inward flow turbine:

In the outward flow turbine the flow is inward from the periphery of the center

Examples of inward flow turbines:

Old type of Francis turbine

Outward flow turbine:

In the outward flow turbine the flow is outward from the center to the periphery.

Examples of outward flow turbines:

Fournryron type turbine

Tangential flow turbine:

In the tangential flow turbines the water strikes the runner in the direction of tangent to the wheel.

Examples of tangential flow turbines:

Pelton wheel turbine

Mixed flow turbine:

In the mixed flow turbine the water enters into the runner in the radial direction and abandon the water in the axial direction

Examples of the mixed flow turbine:

Modern Francis Turbine

Sponsored Links: