One popular alternative is the vertical-axis wind turbine that utilizes the Savonius design, which features a pair of simple hollow half cylinders.
The design is simple and cheap, but because the cylinders are pushed by drag rather than aerodynamic lift the way long wind turbine blades are, the Savonius turbine captures only one-third the power of a commercial wind turbine. In fact, it’s the least efficient design for a wind turbine.
Recently, Man Mohan and Ujjwal K. Saha, mechanical engineering researchers at the Indian Institute of Technology at Guwahati, looked at ways to optimize the Savonius turbine. They hit upon using a genetic algorithm to produce various new shapes that could be tested in a computational fluid dynamics software package. The best performing shapes would become the seeds of another set of slightly altered blades. They repeated the steps until they found the optimized shape: a pair of L-shape scoops, slightly offset.
While the simulations were promising, the real test of the new design involved building a scale model and placing it in a wind tunnel. Compared to a Savonius turbine made with simple, semicircular scoops, the optimized wind turbine performed more than 14 percent better under peak conditions and worked better in high winds.
The paper, “Evolving a Novel Blade Shape of a Savonius Wind Rotor Using an Optimization Technique Coupled with Numerical Simulations and Wind Tunnel Tests,” was published in the April 2024 Journal of Energy Resources Technology.
Jeffrey Winters is editor in chief of Mechanical Engineering magazine.
