HYDRAULIC TURBINES AND THEIR CLASSIFICATION

We were discussing a new topic, in the subject of fluid mechanics and hydraulics machine, i.e. an introduction to hydraulic machine in our recent posts.

Now we will focus here to understand the basics of hydraulic turbines and classification of hydraulic turbines with the help of this post. Further we will find out, in our next post, some important terminologies associated with a hydraulic turbine such as Gross head, Net head and efficiencies of a hydraulic turbine.

So let us start here with the basics and classification of hydraulic turbines.

Hydraulic turbines

Hydraulic turbines are basically defined as the hydraulic machines which convert hydraulic energy in to mechanical energy and this mechanical energy will be given to a generator to produce electric energy.

Now there will be one question that how this mechanical energy will be given to electric generator. Electric generator will be directly coupled with the hydraulic turbine and therefore mechanical energy, developed by hydraulic turbines, will be transmitted to electric generator and hence mechanical energy will be converted in to electrical energy.

Electric power developed from hydraulic energy will be considered as hydroelectric power. We have used here term i.e. hydraulic energy that indicates the energy of water.

Classifications of hydraulic turbines

Hydraulic turbines will be classified on the basis of the type of energy available at the inlet of the hydraulic turbine, direction of flow through the vanes, head at the inlet of the hydraulic turbine and specific speed of the hydraulic turbine.

Let us find out here a brief classification of hydraulic turbines as mentioned here.

According to the type of energy at the inlet of the turbine

Impulse turbine:

If the energy available at the inlet of the hydraulic turbine is only kinetic energy, the hydraulic turbine will be considered as Impulse turbine.

Reaction turbine:

If the energy available at the inlet of the hydraulic turbine is kinetic energy and pressure energy, the hydraulic turbine will be considered as Reaction turbine.

According to the direction of flow through runner

Tangential flow turbine
Radial flow turbine
Axial flow turbine
Mixed flow turbine

Tangential flow turbine:

If the water flows along the tangent of the runner, the hydraulic turbine will be considered as Tangential flow turbine.

Radial flow turbine:

If the water flows in radial direction through the runner, the hydraulic turbine will be considered as Radial flow turbine.

If the water flows in radial direction through the runner from outwards to inwards, the hydraulic turbine will be considered as inward radial flow turbine.

If the water flows in radial direction through the runner from inwards to outwards, the hydraulic turbine will be considered as outward radial flow turbine.

Axial flow turbine:

If the water flows through the runner along the direction parallel to the axis of rotation of the runner, the hydraulic turbine will be considered as axial flow turbine.

Mixed flow turbine:

If the water flows through the runner in the radial direction but leaves in the direction parallel to the axis of rotation of the runner, the hydraulic turbine will be considered as mixed flow turbine.

According to the head at the inlet of the turbine

High head turbine
Medium head turbine
Low head turbine

According to the specific speed of the turbine

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

Do you have any suggestions? Please write in comment box.

Further we will find out, in our next post, some important terminologies associated with a hydraulic turbine such as Gross head,Net head and efficiencies of a hydraulic turbine.