People have been tamed the wind energy for their own needs long time ago. From sailboats to windmills, wind has been and still is a very important source of energy throughout human history. In recent years, wind energy has become even more popular. Mankind has seen that this renewable energy source can be a very efficient and sustainable alternative to fossil fuels. We have started building wind farms not only in our usual areas such as mainland, but also along the coast and mountains.
Wind turbines are easily recognizable all over the world. Even if they come in a variety of sizes, but they always have exactly three blades. Maybe a bigger number of blades would increase the efficiency of making electricity? There are scientific reasons why exactly 3 blades are used.
How Does It Work?
Wind turbines that generate electricity are not a modern invention. The first turbine was invented in 1888 by Charles F. Brush. His invention had 144 wooden blades and it could generate 12 kW of power. It may seem trivial, but until the mid-1930s, most of rural areas in the USA depended on wind energy as it was the only source of electricity. With the expansion of power lines, wind farms in rural areas have disappeared and wind energy has become outdated.
Although, we live in the 21st century, modern principles of wind energy are as simple as in the 19th century. Wind is just moving air, and where is any kind of movement, there is a kinetic energy. Wind turbines are designed to impede this kinetic energy, slow it down, and convert it into electricity. This obstacle occurs when the wind collides with turbine blades that are specifically designed to provide maximum energy. However, the design and use of turbine blades is a delicate science that relies on many factors such as aerodynamics and air resistance.
Design and Aerodynamics
The most important factor to consider when designing wind turbine blades is aerodynamics. Aerodynamics defines the properties of a solid object and how it interacts with air. As a result, the blades are more curved than the front parts. When air moves through a blade of this shape, a pressure difference is caused, and the blade moves.
Due to this shape, the air encounters an obstacle and moves faster behind the blade. This causes the rotation of the moving blades and starts the process of electricity generation. When designing wind turbines, engineers need to consider speed and braking aspects to ensure the highest level of efficiency. For example, if the blades are designed to cause high rotational braking, then the energy production efficiency will be decreased. However, if there is not enough braking, the blades can move too fast and make too much noise.
The Optimal Number of Blades
Three blades are standard, but this solution was a compromise. Due to reduced braking, a single-blade wind turbine would be the optimal choice. Especially when it comes to the amount of energy produced. However, a single blade can cause turbine instability. Two-blades would also provide more energy, but turbines with two blades are more prone to a phenomenon called gyroscopic precession when some oscillation of the axis of a rotating object occurs. Any larger number of blades would create more wind resistance, slow down the power production, and it would be less efficient.