## Sunday, 7 July 2019

We were discussing a new topic, in the subject of fluid mechanics and hydraulics machine, i.e. an introduction to hydraulic machinevarious types of hydraulic turbines and some important terminologies associated with a hydraulic turbine such as Gross head, Net head and efficiencies of a hydraulic turbine and also we have seen the fundamental of Pelton wheel or Pelton hydraulic turbine and basics of radial flow reaction turbines in our recent posts.

Now we will focus here to understand the difference between inward radial flow reaction turbine and outward radial flow reaction turbine with the help of this post.

So let us start here with the basics of inward radial flow reaction turbine and outward radial flow reaction turbine in order to understand the difference between both types of radial flow reaction turbines.

### First of all, let us recall the fundamentals of radial flow reaction turbine

Let us first understand the meaning of radial here and then we will see the meaning of reaction in radial flow reaction turbines.

Water will flow in radial direction in radial flow reaction turbines. Water may flow radially from outwards to inwards or from inwards to outwards.

If water flows through the runner from outwards to inwards, turbines will be termed as inward radial flow turbine.

If water flows through the runner from inwards to outwards, turbines will be termed as outward radial flow turbine.

If water flows through the runner from outwards to inwards, such turbines will be termed as inward radial flow turbines.

Following figure shows the inward radial flow reaction turbine

Water will enter in to the casing, from penstock, and from casing water will flow towards stationary guiding wheel. The guiding wheel will have guide vanes which will direct the water to enter the runner and turbine runner will have moving vanes.

Water will flow over the moving vanes in the inward radial direction and water will be discharged at the inner diameter of the runner.

Therefore the outer diameter of the runner will be considered as the inlet and inner diameter of the runner will be considered as the outlet.

If water flows through the runner from inwards to outwards, such turbines will be termed as outward radial flow turbines.

Following figure shows the outward radial flow reaction turbine

Water will enter, from casing, at the center of stationary guiding wheel. The guiding wheel will have guide vanes which will direct the water to enter the runner which is around the stationary guide wheel.

Turbine runner will have moving vanes and water will flow over the moving vanes in the outward radial direction and water will be discharged at the outer diameter of the runner.

Therefore the inlet diameter of the runner will be considered as the inlet and outer diameter of the runner will be considered as the outlet.

Do you have any suggestions? Please write in comment box.  Further we will find out, in our next post, Francis turbine

### Reference:

Fluid mechanics, By R. K. Bansal