Pelton Wheel is a common example of an Impulse Turbine.
This turbine is developed by L.A.Pelton.
Pelton Wheel Turbine is used for high water head and low discharge.
Hence in Hydro-Electric Power Plant Impulse Turbine and Reaction turbines are used based on the requirement.
So, here are the Main Parts of the Pelton Wheel
It is the circular guide mechanism, which guides the water to flow in the designed direction. This also regulates the flow rate.
A conical needle or spear operates inside the nozzle in an axial direction.
This spear controls the quantity of water flowing through the nozzle.
The area of the jet is reduced by pushing the spear forward inside the nozzle.
Hence this results in a reduction in water quantity flowing through the jet.
Similarly, if the spear is pushed back, a greater quantity of water is flowing through the jet.
The spear is controlled by an automatic governing mechanism or by hand depending upon the need.
Some additional nozzles, known as Bypass Nozzles are provided.
This way we avoid the bursting of pipes in case of the sudden closing of the water supply.
The bypass nozzle doesn’t allow water to strike the buckets.
In some Pelton Wheel Engineering defectors are provided in a nozzle, which is used to deflect the water jet.
Hence preventing it from striking the buckets.
Runner and Buckets
The runner of a Pelton Wheel consists of a circular disc fixed to a horizontal shaft.
On the periphery of the runner, a number of buckets in hemispherical or bowl shape will be fixed uniformly.
The surface of buckets is made very smooth to avoid friction losses.
The material of the bucket for the low water head is Cast Iron.
For a high head, they are made from bronze, Stainless Steel, or another alloy.
Special Alloys are used to manufacture buckets when water is chemically impure.
The buckets are generally bolted on the runner disc.
So, when a few buckets are worn and need a replacement that can be done.
The casing is, generally, made of cast or fabricated parts, to safeguard the runner and bucket assembly against accidents.
And also to prevent the splashing of water and leading the water to the tailrace.
The casing of the Pelton Wheel does not perform any hydraulic function.
To reduce the speed of the runner, a breaking jet works as a break.
These are very small nozzles in order to bring runners to rest in a short time period.
The braking jet works on the backside of buckets.
This jet brought the turbine to rest for necessary action done by the engineering dept.
Besides this information, you are suggested to read something more from below engineering books
If you like the post, share it with your friends and also on social sites.