A windmill is a device that transforms wind energy into rotatory power through blades called vanes, especially for grinding grains (mills). This term also refers to wind turbines, wind pumps, and some other functions. The term “wind engine” sometimes uses to define this type of equipment.
These turbines were used from the middle ages to the early modern period. In the 9th century, horizontal wind turbine firstly introduced in Greater Iran and vertical wind turbines appeared in northwestern Europe in the 12th century. As a symbol of Dutch culture, there are currently around 1,000 windmills in the Netherlands.
Types of Windmills
There are many types of windmills, but the most famous types are given below.
1) Horizontal Windmill
2) Vertical Windmill
1) Horizontal Windmill or wind turbine
Main Article: Types of Wind Turbine (HAWT)
These windmills are the most known because of their excellent efficiency and strength. In order to mount the rotor shaft on top of the tower and expose the turbine to strong winds, the base of the tower must be very strong. If the turbine vanes have a vertical direction to the wind compared to a wind turbine with a vertical axis, more power can be generated by rotating the blades. This type of turbine construction needs strong support from the tower to support the weight of the generator, gearbox, and blades. A horizontal wind turbine also requires a large crane to lift the parts to the tower’s top.
2) Vertical Wind Turbine
These types of wind turbines known as a vertical turbine because these have blades in the vertical direction to the wind. Wind turbines with a vertical axis are less affected by changes in wind path, as the blades rotate around a rotor axis that is vertical to the ground compared to wind turbines with a horizontal axis. This connection between the shaft and the blades allows the turbine to follow the direction of the wind without turning.
How Does Windmill Work?
The number of windmill vanes was decided after numerous trial and error methods. It found that all 3 blades were the best for excellent efficiency. That’s the way; each windmill has 3 blades. The wind is the energy source for a windmill. As the blade touches the wind, the blade moves, and the shaft rotates to generate electricity. A generator is a mechanical device that transforms rotational energy into electricity.
Components of Windmill
The major components of the windmill are given below:
It measures the speed of the wind and sends this speed data to the controller.
Disc brakes can be operated hydraulically, electrically or automatically to stop the rotor in emergency conditions.
The controller starts up the turbine at the velocity of the wind of approx. 8-16 km / h and off at a velocity of approx. 90 km / h. Turbines cannot run at wind speeds of more than 90 km / h as they can be damaged in strong winds.
The blades of a windmill work on the same principle as the wings of an airplane. One side of the blade has a flat shape, and the other side is bent. The air flows faster along the bend edges and creates a pressure variance on both sides of the blade. The air pushes the blades to balance the pressure variance. This will rotate the blade.
The nacelle has a complete set of gears and a generator. The rotating blades are connected to the generator via gears. These gears change the comparatively slow rotations of the blade into generator speeds of around 1500 rpm. This generator then transforms the rotary energy of the blades into electricity.
The gondolas and vanes are fixed on the tower top. This tower structure should not keep the rotor blades too far from the ground and at ideal wind speeds. The tower is usually located 50 to 100 m above the ground or on the surface of the water. Offshore towers are generally set at the bottom of the water, but research is currently being carried out to develop towers that float on the surface of the water.