Go Fly a Kite!

[SSDD]

While 4 or more blades of the same size gives more power than 3, it's not much more. More blades means more turbulence created, so each additional blade gives diminishing returns. More blades would be more weight, so they'd have to be smaller, as the hub can only support so much weight. 3 larger blades gives more power than 4 or more smaller blades.

All well stated. Just to further strengthen the point:

According to Betz's law, a wind turbine can harvest at most 59.3% of the kinetic energy of the wind. Modern turbines (3 blades) reap something in the order of 50%. That serves to show that the added gains with more blades would be minuscule, while adding further strains on the system, predominantly at higher wind speeds, resulting in way higher costs, as you've pointed out.

No that's not what he said. He said that it was a turbulence problem(already with just 3 blades)
I said there is not & showed him why not and now you come along after you made yourself an instant expert because you got wifi and pretend to know something about aerodynamics just like him or her, who knows these days. Either one of you is brain dead the moment your wifi goes down

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Typical know nothing warmer...how smart can they be...I mean, they have fallen for one of the biggest hoaxes ever...history will put them on the same shelf with people who accepted phrenology, and bleeding as high science.

 

[Crick]

And the science you have to back up that position? Does it come from ANYWHERE other than your twisted and vacuous brain?

CurioCity - CurioCité | Why don't wind turbines have more than 3
Wind Turbine Blades
If you've ever had the opportunity to watch a wind turbine start, you would have noticed that the blades start rotating very slowly and then begin accelerating faster and faster. This is because of the aerodynamic design of the blades.

The blades of a wind turbine are shaped similar to an airplane wing, with one side (rear) much more curved than the other (front). With a wing, air flows fastest over the top which reduces the pressure and causes the lift needed for the aircraft to fly. Turbine blades also rely on pressure differentials due to changes in air speed in order to operate.

When the wind begins blowing and passing over the blade, air behind the blade starts travelling at a higher velocity than air in front of the blade. In fact, the greatest velocity is at the rounded front edge which creates a pocket of low-pressure air. This literally pulls the blade forward and we get the start of rotation.

Once the blades are rotating, they create their own headwinds (like what we feel on our face when cycling). The velocity of this additional wind helps to lower the pressure on the back side of the blade and contributes to even more lift. This causes the blade to rotate faster and produce additional headwind. The net effect is that the blades of a turbine spin more rapidly until they reach their maximum velocity.

But why 3 blades?
The more blades there are on a wind turbine, the higher will be the torque (the force that creates rotation) and the slower the rotational speed (because of the increased drag caused by wind flow resistance). But turbines used for generating electricity need to operate at high speeds, and actually don't need much torque. So, the fewer the number of blades, the better suited the system is for producing power.

Did you know? About 90% of the installed wind turbines today have three rotor blades.

Theoretically, a one-bladed turbine is the most aerodynamically efficient configuration. However, it is not very practical because of stability problems. Turbines with two blades offer the next best design, but are affected by a wobbling phenomenon similar to gyroscopic precession.

Since a wind turbine must always face into the wind, the blades will have to change their direction vertically when there is a shift in wind direction. This is referred to as yawing. In the case of a two-bladed system, when the blades are vertical (i.e., in line with the tower and the axis of rotation) there is very little resistance to the yawing motion.

But when the two blades are in the horizontal position, the blades span a greater distance from the axis of rotation and so experience maximum resistance to yawing (notice how a spinning figure skater slows down when they bring their arms away from their body. As a result, the yawing motion starts and stops twice per revolution, and this leads to stress on the turbine due to blade chattering.

On the other hand, a turbine with three blades has very little vibration or chatter. This is because when one blade is in the horizontal position, its resistance to the yaw force is counter-balanced by the two other blades. So, a three-bladed turbine represents the best combination of high rotational speed and minimum stress.