What is Horizontal Axis Wind Turbine : Working & Its Applications

A wind turbine is a rotating mechanical device, used to change wind energy from kinetic to electrical. These are available in different sizes with either vertical or horizontal axes. The wind turbine is an essential device in a wind power station or wind park. So, the selection of this turbine for the development of wind park projects can be done based on different parameters like physical dimensions, nominal power, available area, wind potential, etc. Wind turbines are available in two types like horizontal axis wind turbine & vertical axis wind turbine. This article gives an overview of a horizontal axis wind turbine.

What is Horizontal Axis Wind Turbine?

At present, the most commonly used wind turbine is HAWT or Horizontal Axis Wind Turbine. These turbines use airfoils (aerodynamic blades) which are connected to a rotor by positioning in upwind or downwind. These are available either in two-bladed or three-bladed and operate at high speed.

Current horizontal axis wind turbines utilize the aerodynamic lift force to rotate every rotor blade similar to an airplane flies. Generally, the aerodynamic lift force works once they exposed to winds around both the higher and lower segments of a blade. The pressure difference which is formed between the top & bottom faces of the blade generates a force in the top direction of the blade. The horizontal axis wind turbine line diagram is shown below.

HAWTs can be used in any direction of wind through the furling system. This system rotates the face of the rotor to come perpendicular to the wind’s direction. Therefore, the face of the rotor can be moved to that direction where it can face wind at the highest speed.

Horizontal Axis Wind Turbine Construction and Working

The construction of a horizontal axis wind turbine can be done with different components. So the horizontal axis wind turbine components mainly include foundation, nacelle, generator, tower, and rotor blades.

Horizontal axis wind turbines include the rotor shaft & electric generator which are arranged at the top of the tower. Small wind turbines use a simple wind vane, whereas larger wind turbines use wind sensors that are connected through an auxiliary motor. Most wind turbines contain a gearbox, which is used to change the blade rotation from slow to fast, so used to operate an electric generator.

Foundation

For any wind turbine, the foundation gives support to the tower because the wind turbine includes different parts which weigh in tonnes.

Tower

A tower is used to give support to the rotor hub and nacelle on the top of the window turbine. The materials used to make this are concrete, tubular steel, or steel lattice. While designing this turbine, the height of the tower is very important because wind speed enhances with height. So taller towers allow these turbines to capture a huge amount of energy & produce more electricity.

Generally, the output power of a wind turbine enhances by increasing its height & also decreasing the turbulence within the wind. There are different wind turbine towers available like tubular, lattice, guyed wind, tilt upwind & free standing.

Wind Turbine Blades

These blades are mainly used to remove the kinetic energy (KE) of wind & change it to mechanical energy. These types of blades are designed with wood-epoxy or fiberglass-reinforced polyester. These turbines include a minimum of one and maximum multiple blades depending on the design.

Most of the horizontal axis wind turbines include three blades that are connected to the rotor hub. In earlier days, multiple blades based turbines are used as a single blade, two-blade and three blades for grinding & pumping water, etc.

Nacelle

The nacelle includes different components which are used to operate the wind turbine efficiently like the gearbox, brakes, controller, low & high-speed shafts & generator. It is arranged at the top of a tower & a wind vane is arranged on the nacelle.

Hub

A rotor hub is used to connect a shaft and rotor blade of the wind turbine. The hub includes blade bearings, bolts, internals & a pitch system. These are designed with cast iron, welded sheet steel & forged steel. These are available in two types like Hinge-less hub & Teetering hub.

Gear Box

In wind turbines, a gearbox is used to change high toque power with low-speed which is received from a rotor blade to low torque power with high speed. This power is used for the generator. The gearbox is connected in between the generator and main shaft for enhancing rotational speeds from 30 – 60 rpm to 1000 – 1800 rpm.

Gearboxes are made with different materials like superior quality alloys, aluminum cast iron, stainless steel, etc. In wind turbines, there are three types of gearboxes are used like Planetary, Helical, and Worm.

Generator

The rotating mechanical energy of the gearbox is given to the generator through the shaft. It works on ‘Faraday’s law of electromagnetic induction principle. So it changes the energy from mechanical to electrical.

Horizontal Axis Wind Turbine Working

Once the wind blows, a wind turbine changes the kinetic energy from the motion of the wind into mechanical through the revolution of the rotor. After that, this converted energy can be transmitted through the shaft & the gear train toward the generator. Further, this generator converts the energy from mechanical to electrical to generate electricity.

The wind flows on both faces of the airfoil-shaped blade although flows faster on the upper face of the airfoil to create a low-pressure region on the airfoil. The pressure difference between both the top & bottom surfaces results within the aerodynamic lift.

As the blades of a wind turbine are constrained to move in a plane with the hub as the center, the lift force causes rotation about the hub. In addition to the lift force, a drag force perpendicular to the lift force prevents rotor rotation.

The horizontal axis wind turbine design mainly includes a high lift to drag ratio, especially for the blades. So this ratio can change through the blade’s length to optimize the output energy for the wind turbine at different speeds of wind. The generator & rotor shaft are arranged within the box at the top of the array.

Horizontal Axis Wind Turbine Types

The horizontal axis wind turbines are available in two types like the following.

• Upwind Turbine
• Downwind Turbine

Upwind Turbine

In an upwind wind turbine, the rotor is arranged at the upside of the tower. The main function of this turbine is to avoid the shadow of wind on the backside of the tower. At present, this design is used in most HAWTs because it is nonflexible & arranged at some distance from the tower.

Downwind Turbine

In a downwind turbine, the rotor is arranged at the downside of the tower. In this turbine, firstly the wind is faced toward the tower, then to the blades of the rotor. This wind turbine faces some differences within wind power because of the passage of the rotor through the wind shade of the tower. Here, the rotor is behind the nacelle of the tower which causes fluctuations within wind power.

Advantages and Disadvantages

The advantages of a horizontal axis wind turbine include the following.

• It includes high output power as compared to the vertical wind turbine.
• A tall tower gets stronger winds once the wind shear alters.
• High efficiency.
• It is not expensive as compared to vertical type turbine.
• It has high reliability.
• It has a high rate of capacity.
• Its rotational speed is high.
• It is more consistent.
• These turbines are self-starting.
• In this turbine, the vanes are located one face of the turbine center of gravity, which improves stability.
• It can bend the blades so that the turbine blades have the best attack angle.
• The blade can also tilt the rotor during a storm to reduce damage

The disadvantages of horizontal axis wind turbine include the following.

• These are available in large size.
• Weight is high.
• We cannot move easily.
• Installation is difficult.
• High noise.
• To design this wind turbine, large machinery is needed.
• Its maintenance is difficult as compared to other wind turbines.

Applications

The applications of horizontal axis wind turbines include the following.

• These are the most frequently used wind turbines for commercial and industrial purposes due to their large power output and high efficiency.
• These are mostly used in wind farms
• Horizontal axis wind turbines achieve better power output & higher energy efficiency, so used in large-scale wind power plants & also for electricity generation.
• In industrial plants, large-scale wind farms, or national projects, these wind turbines are most frequently seen. So they are the perfect solution for the production of mass electricity.

The list of wind turbine manufacturing companies around the world includes the following.

• World Wind in India
• Suzlon in India
• RRB Energy Limited in India
• Inox Wind in India
• Elecon Engineering in India
• Southwest company in the USA.
• PacWind in the USA
• China Guodian Corporation in China
• Shanghai Electric in China
• SANY in China
• Goldwind in China
• Envision Energy in China
• CRRC in China
• TUGE Energia Company in Estonia.
• Guietrevolution Company in the UK
• Hi-VAWT in Taiwan
• Enessere in Italy
• Borny in Spain
• UNISON in South Korea
• Senvion in Germany
• Nordex SE in Germany
• Enercon in Germany
• Acciona in Spain
• NoyaWind Russia

Which type of wind turbine is most efficient?

Vertical wind turbines are more efficient as compared to other turbines because these turbines increase up to 15% performance.

How many acres do you need for a wind turbine?

A 2 MW wind turbine uses 40 to 70 acres of land to avoid interference between turbines.

Which alternator is best for wind turbines?

In a wind turbine, a low rpm 3-phase AC alternator is used which ranges from 50kw to 1000KW

Why horizontal axis turbines are preferred over vertical axis wind turbines?

Because the horizontal wind turbine generates more electricity as compared to others from a specified amount of wind.

How many amps should an alternator put out at idle?

The alternator at 13.5V will output 40 amps. Once the load goes above 40 amps then the voltage will fall under the 13.5V level.

Thus, this is all about an overview of Horizontal axis wind turbine blades, construction, working, types, advantages, disadvantages, and their applications. The combined wind turbines like horizontal and vertical will increase the production volume & efficiency as compared to the separate wind turbine. Here is a question for you, what is the difference between Horizontal & Vertical Axis Wind Turbine?