Iowa State Aerospace Engineers Anupam Sharma and Hui Hu are exploring the possibility of adding a smaller, secondary rotor to wind turbines. The engineers studied the base of existing turbines and found two major problems. First, they are big round structural pieces that don’t harvest any wind energy because they are not shaped like an airfoil. Second, the large base of the blades actually disrupt the wind, causing a wake behind them which reduces the energy harvesting capacity of any downwind turbines. Hu says that a turbine in the slipstream of another “can lose 8 to 40 percent of its energy production, depending on conditions.”
Their solution? Add a second, smaller rotor. “To try to solve these problems, we put a small rotor on the turbine,” Hu said. “And we found that with two rotors on the same tower, you get more energy.” Lab tests and computer simulations found the extra blades and increase the energy harvest by up to 18 percent. “These are fairly mature technologies we’re talking about – a 10 to 20 percent increase is a large change,” Sharma said.
Using a one-year, $116,000 grant from the Iowa Energy Center, the pair is currently using wind tunnels and computer simulations to study the dual rotor idea and measure power outputs and wind loads. The questions they hope to answer are: How is the wake distributed? Where are the whirling vortices? How could the wake be manipulated to pull down air and recharge the wind load?
They plan to use the research results to find the best aerodynamic design for a dual-rotor turbine. The goal is to find out where the second rotor should be located, how big it should be, what kind of airfoil it should have, and if it should rotate in the same direction or in the opposite direction.
The above image (courtesy of Anupam Sharma) shows air flowing through a dual-rotor turbine. Read more details about the research over at the Iowa State website.
What do you think? Could a second rotor make wind turbines more efficient? Leave your comments below…
- K_A_JTveksam om det om det ökar verkningsgraden i samma takt som kostnadsökningen?
- dcard88I agree. lol
- Installing windwheels with douInstalling
windwheels with double rotor is the wrong way in the development of wind
energy. The study of modular windwheels and test them for 4 years vetropoligone
VIESH showed that the effectiveness of efficiency increases by 5-8%. The tests
were conducted in a wind tunnel and field conditions for 3 years from 2009-2013
g vetropoligone Istra, Moscow Region team of scientists led by wind power
Dorzhiev SergeiCurrently,
the team headed by S.S. Dorjiev offered, manufacture and test the wind wheel
with the efficiency of 400-500%, in contrast to windwheels double rotor. If
you want can be contacted by DSS.61@mail.ru - Jasonmore torque can the hull handle it
- KI have been around walls or buildings that channel airflow. Why can’t we make a wind tunnel to compress the airflow into a steady stream then put turbines into the stream we want? I see scientists battling with inconsistent wind but why can’t we conform the wind first then stick a turbine into that wind stream?
- MatthiasThe answer is pretty simple – the combination of the needed structure and a resulting smaller wind turbine is more expensive than the current concept of a bigger free flow wind turbine. It has been studied in various places, but if you want a literature starter, try the excellent book “Innovation in wind turbine design” by Jamieson.
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