A DUAL-ROTOR WIND TURBINE: A PROMISING TECHNOLOGY FOR ENHANCED WIND ENERGY CONVERSION – A REVIEW

The continuous growth of global energy demand and the urgent need to reduce dependence on fossil fuels have intensified research on high-efficiency renewable energy technologies.Among various renewable sources, wind energy has emerged as a mature and cost-effective solution.However, conventional single-rotor wind turbines (SRWTs) are fundamentally limited by aerodynamic efficiency, primarily governed by the Betz limit.To overcome these limitations, the dual-rotor wind turbine (DRWT) concept-featuring two coaxial rotors rotating in the same or opposite directions-has gained increasing research attention.This review paper presents a comprehensive discussion of the dual-rotor wind turbine concept, focusing on its aerodynamic performance, wake characteristics, power coefficient enhancement, mechanical transmission systems, and atmospheric boundary layer effects.Comparative studies between DRWT and SRWT configurations are analyzed to highlight improvements in energy extraction, wake recovery, and load characteristics.Experimental, numerical, and simulation-based investigations reported in the literature demonstrate that DRWTs can achieve higher power coefficients, improved wake mixing, and reduced downstream velocity deficits without significantly increasing structural loads.The review also examines gearbox-based and gearless drivetrain approaches for dual-rotor systems.Overall, the dual-rotor wind turbine is identified as a promising future technology for enhancing wind farm efficiency and sustainable power generation.