# How to Make a Windmill?

View Notes

## What is Windmill?

A windmill is a big structure also called a mechanical device that transforms wind energy into electrical energy. It is a big structure that contains sails mounted on a rotating shaft.; these rotating sails help transform windâ€™s kinetic energy into electricity.

These sails make an angle so that when they rotate, the force of the wind against them is divided into the two following components:

• One in the plane of sails, andÂ

• Another imparts rotation

Windmills are prime movers that have replaced humans as a source of power and in this article, you will learn to make this device.

### How to Make a Windmill?

We know the use of windmill is to generate electricity. The steps to build a paper windmill are as follows:

• Take an 8 inch by 8-inch square paper.

• Wrap it corner-to-corner, do the same thing for the rest two corners.

Â Â Â Â Â Â Â Â Â Â (Image to be added soon)Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â

• Now, after folding a square paper, take a midpoint on it and cut from both ends, and do the same thing on the other side.

• Since there are two corners after cutting around each corner of a square, now pierce along each alternative corner with the help of a pin. Do the same in the centre of the square also.

• Now, fold these pierced corners and leaving the unpierced ones as such. We get tilted and folded blades, as shown in the image below:

Â Â (Image to be added soon) (Image to be added soon)Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â

• Put a thermocol ball on the pointed end of the pin at the backside of this folded arrangement.

• Now, attach a straw through this thermocol ball or we can pin a soft pencil to this ball.

So, now our windmill is ready, you can see the final image of a windmill below:

Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â (Image to be added soon)

Bring these windmills in the open air, as the wind blows, these blades will start rotating.Â

### What is Windmill and How it Works?

Windmill has been a useful source of power from last many years, even during the World War-I, windmills maker produced 10,000 farm windmills each year for water-pumping.Â

At present, windmills are used for electricity generation, and this electricity generation is possible because of the blades that are constructed by the concept of aerodynamic analysis and the other performance-enhancing equipment.Â

### Working Principle

A windmill is a big structure contains sails that are attached by a fixed rotating shaft, as you can see in the image below. The rotating shaft rotates these blades that help convert the kinetic energy of wind into electricity.Â

Now, letâ€™s understand its basic working:

When a blowing wind forces the blades, these rotating blades generate electricity because of the generator attached to the windmill. Do you know how blowing wind turns a wing?

If we closely look at the cross-section of the blade, it has a lot many airfoils on the surface.Â Â

The concept of an airfoil is simple. Whenever there is a pressure difference between the two surfaces, an upward force acts on the blade, which is a dynamic lift.Â

(Image to be added soon)Â Â Â

Since all the blades have airfoils, in this way, a lift generates in all the three blades, which makes these wind turbine blades turn, as we encounter with the windmills in the farm.

### Relative Velocity of Wind Turbines

Just like moving trains,Â  wind turbines also experience the wind relatively. So the relative velocity of the wind is given by the following formula:

V RELATIVE = VWIND - VBLADE

So, the relative velocity is the difference between the velocity of the wind and that of a blade. So thatâ€™s why blades are tilted in such a way that they align to the relative wind speed.

Now, as the blade velocity increases to the tip, the relative velocity becomes more inclined towards the tip, which means a continuous twist is given to the blade from the root to tip.Â

Since due to low mechanical strength and wind noise, the blades donâ€™t rotate and give high rpm with a generator. So, how to gain maximum speed?

### How to Gain Maximum Speed in a Windmill?

Now, what we do is, we connect a gearbox before the generator, which helps achieve a high-speed ratio of 1: 90 (cut-off speed of 80 kmph). A brake is also fitted in a nacelle that helps tackle the wind arrest during windy conditions. Consecutively, the electricity generated is transferred to the transformer filled at the base of the windmill.Â

This is how a windmill works. Now, we will learn about the types of windmills.

### Types of Windmills

There are various types of windmills, so letâ€™s understand their types one-by-one:

• Post mill

• Smock mill

• Fan mill

• Tower mill

### Use of Windmill

Windmills have aÂ  mounted wind turbine that captures most energy and performs various tasks that have replaced human beings as a source of power. They are used in the following places:

• They are used for pumping water,

• For grinding grains, and

• Generating electricity.Â

1. What is a windmill and how does it work?

A windmill has a simple principle, instead of using fans or motor, the wind turbines mounted at the back of the blades help capture wind energy and convert it into electrical energy, which we use for pumping water, grinding grains, etc.

2. Write the advantages of windmill.

• Cost-effectiveness

• Clean fuel source

• Domestic source of energy

• Increases US industry growth

• Creates jobs

3. Write the disadvantages of windmill.

• The wind is not consistent

• May decrease the local bird population:Â

(As per the latest survey, a minimum of 20,000 - 573, 300 birds got killed by the windmills in the US)

• Installation takes up a lot of a land area.

• Windmills can be a safety hazard.

4. When was the first windmill invented? Which country is known as the city of windmills?

The first windmill was invented in 1854 by Daniel Halladay in his Connecticut machine shop. The Netherlands is known as the city of windmills. However, it produces very little power, i.e., Quartz.

5. Why do wind turbines fail?

Wind turbines fail because of the following reasons:

• Damage or power regulator failure

• Lightning strikes

• A poor architecture

• Blades require costly repairs and revenue lost