I'm trying to design a quasi-simple vertical axis wind turbine, and a coworker came up with this design to focus the wind as it reaches the turbine in a wind tunnel. He says that there's going to be turbulence caused by some of the design factors, but I'm not quite sure why and he doesn't know why, either. Why, and where, would this design cause turbulence, and what improvements could be made to improve it?
2 Answers
The diagram is not labeled, but if the green lines are rigid walls I can see that the wind is given angular momentum by the shape. Angular momentum is conserved and will create turbulence in a fluid.
This does create turbulence which, simply put, would reduce the velocity of the wind hitting the turbine thus lower output can be taken from the turbine. The most important variable for wind turbine efficiency is the wind speed and in this case you will have a lower windspeed, because the walls would cause turbulence and there will be already some turbulence eddies even before the wind turbine as opposed to the normal case which is turbulent from after the wind turbine. This is also why as a rule of thumb wind turbines should be 3 to 5 times the length of the rotor diameter wawy from each other, because if lower, the turbulent wind flow would not have much speed to give to the turbine.