Understanding energy turbine start-up
The world is expected to need 40 percent more energy in the next 30 years, and much research is underway to help fill that demand. Darrieus, or lift-driven, turbines are a promising type of vertical-axis turbine that show considerable power generation and rotor efficiencies within built-up urban areas. However, these types of turbines have a debilitating flaw — they struggle to self-start, especially in conditions with fluctuating inflows.
Selvarajoo and Mohamed-Kassim investigate the aerodynamics of a Darrieus rotor to understand the underlying problems of these rotors during their start-up.
“By understanding the fundamental causes of this key problem, we and other researchers will have more clarity to think further and come up with newer and better strategies to improve these turbines,” said author Zulfaa Mohamed-Kassim.
The authors simulated a three-bladed Darrieus rotor using vortex modeling and dedicated software for turbine simulations. With a low computational cost, this method allowed them to simulate a large number of tests to analyze different cases and scenarios.
The results showed the “dead band” region — a primary obstacle for the start-up where the thrust coefficient is negative — is caused by reverse dynamic stalls on the blades during the early part of the self-starting process.
Motivated by these early results, the authors developed another software to automate turbine aerodynamics analysis.
“We are excited that the software we developed throughout this research can be useful to others, regardless of whether they are focusing on similar problems as ours, or different problems entirely,” Mohamed-Kassim said.
The authors intend to further study the flow physics of the system to help improve energy production from Darrieus rotors.
Source: “The effects of dynamic stalls on the aerodynamics and performance of a Darrieus rotor during self-start,” by Shaza Rae Selvarajoo and Zulfaa Mohamed-Kassim, Physics of Fluids (2024). The article can be accessed at https://doi.org/10.1063/5.0180107 .