How does a Pelton Wheel Turbine work?

Pelton wheel turbine is a kind of tangential flow impulse turbine, in which the pressure force of the water is converted into energy that travels to produce a high-speed jet of water, with the wheel spinning. It is also called a Pelton turbine. It is different from a reaction turbine, such as a reaction turbine doesn’t change the flow direction while a Pelton wheel turbine changes the flow direction.

Pelton wheel turbine working

The Pelton turbine working principle is as follows:

1. Water is brought from a high source through a long pipe called a tailrace.
2. Fixing the nozzle to the end of the pressure hose accelerates the flow of water at high jet speeds and discharges to atmospheric pressure.
3. The jet strikes the bucket drive path, splits the jet into two bucket halves, and the wheels start spinning.
4. The force of movement of the jet hitting the bucket is reduced and, since the bucket is spherical, the guided jet changes direction rotates and U-turns on its tail.
5. Under normal circumstances, the jet entry angle is between 1 to 3 degrees, and the jet angle deviates after hitting the bucket, between 165 degrees to 170 degrees.
6. Under no circumstances should the Pelton wheel collect water in the adhesive line of the seal.
7. Two Pelton wheels can be mounted on one axle to generate more energy, or two water jets can be routed simultaneously on one Pelton wheel.

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Pelton Wheel Turbine Parts:

The Components of the Pelton Wheel Turbine are as follows.

1. Penstock
2. Nozzle and Spear
3. Runner and buckets
4. Casing
5. Breaking Jet

1) Penstock

Penstock controls the flow of water and can also be used as a guide for the flow of fluid. It is like a channel or tube.

2) Nozzle and Spear

The nozzle is used to increase the force of movement of the water and the impact on the bucket connected to the runner.

3) Spear

The amount of water hitting the bucket controls by a spear. A needle-shaped nozzle is installed to regulate the flow of water hitting the runner’s bucket or blade. Its power is from a handwheel.

When the spear moves back and forth respectively, the water flow rises and falls and can operate with a handwheel (axial action).

4) Casing

A casing is the most important component of the Pelton wheel turbine. The entire arrangement of rails and buckets, inlets and brakes are covered by the casing. The Pelton turbine housing does not perform any hydraulic operation but prevents water from exploding during operation and helps remove water from the tailrace.

5) Braking jet

The brake nozzle is used to stop the wheel from running. This happens when the inlet nozzle is closed with the help of a lens, and the jet of water in the bucket stops. But due to inertia, even if the inlet nozzle is entirely closed, the runner does not stop rotating. To avoid this, a brake nozzle is provided. The brake direction directs the water to the tail of the bucket to stop the wheels. The jet driven by the brake nozzle is called a jet brake.

Pelton Wheel Turbine Advantages

The advantages of the Pelton wheel turbine are given below:

1. The Pelton turbine has a simple design and simple structure.
2. Clean water does not cause rapid headwear.
3. Easier to maintain and inspect than other turbines.
4. Cavitation is not a permanent hazard.
5. Compared to the reaction turbine, the overall efficiency is relatively high.
6. There is no drain hose here.
7. It is possible to work with a relatively low Q (discharge) flow rate.
8. It is the most efficient among hydraulic turbines.
9. Pelton turbine components are easy to assemble. Nothing complicated here.
10. Water hitting and exiting the runner exactly at atmospheric pressure.
11. Tangential flow turbine. It can move in the direction of the axial or radial flow.

Disadvantages

The disadvantages of Pelton Wheel Turbine are following:

1. The head is not easily controllable in the Pelton wheel turbine because it works with a long head.
2. The ratio between the maximum and minimum heads may be lower.
3. Compared to the total height, the operation cannot be used when the tailwater level changes significantly.
4. The mechanical efficiency of the Pelton turbine decreases faster as compared to the Francis turbine.
5. If Pelton turbines were used in place of Francis turbines for power generation, the necessary runners, generators and power plants would be large and affordable.

Applications of Pelton Turbines

The application of Pelton Wheel Turbine is following:

1. Pelton turbines are used in hydroelectric plants that require ever-lower emissions.
2. They are used to achieve higher fluid speeds for maximum power and efficiency [because turbines and impellers are designed so that the speed of the water jet is twice the speed of a rotating cylinder].
3. Pelton wheel is used to start a generator, connected to the turbine shaft where mechanical energy is converted into electrical energy.

Check out: What is Reaction Turbine? Types, Pros and Cons