PELTON,KAPLAN AND FRANCIS TURBINE

PELTON TURBINE:The pelton wheel turbine is impulse turbine,which is of tangential flow type.

In this turbine energy at the inlet of turbine is in the form of kinetic energy.This is used for low flow rate and high head.Pressure through out remains atmospheric.

The main parts of pelton turbine are:

1)Nozzle or flow controlling:It controls the rate of flow as per requirement of variable power.

2)Runner or bucket:It is of shape double hemispherical seperated by splitter which devides water without shock.

3)Casing:Casing has not hydraulic function.It only prevent water from splashing.

4)Braking jet:To stop the runner in smallest possible time.

                                                      Fig:Pelton wheel turbine runner

FRANCIS TURBINE:Francis turbine is reaction turbine.In this type of turbine at inlet is in the form of both kinetic as well as pressure energy.The runner is completely enclosed that is it is air tight.As the water flows a part of pressure energy is converted into kinetic energy.Runner is always full of water.It is used for medium head and medium flow.It is radially inward mixed flow turbine.

The main parts of francis turbine are:

1)Spiral Casing:It distributes the flow over periphery.It has reducing crossestion  such that entrance velocity is same through out.

2)Guide Mechanism:It converts part of pressure into kinetic energy.Using it flow rate can be regulated and direct water to runner.

3)Runner:It is the rotaing element of turbine.When water flows through turbine its angular momentum is reduced thereby producing torque and rotating the runner.

4)Draft tube:It converts large proportion of kinetic energy rejected at the exit of turbine into useful presuure energy.It permits negative head to be stablished at the outlet of turbine thus turbine can be palce above tail race without compromising the head available.

                                                   Fig:Main parts of Francis turbine

KAPLAN TURBINE:Kaplan turbine is reaction turbine.In this type of turbine at inlet is in the form of both kinetic as well as pressure energy.It is used for low head and high flow rate.

The main parts of kaplan turbine are:

1)Scroll casing

2)Guide vane mechanism

3)vane and runner

4)Draft tube

Fig:kaplan turbine runner