Design an‎d optimization of a wind system with two parallel vertical axis Darius turbines equipped with J-shaped blades

10/22/2026 12:00:00 AM

Abstract In recent years, vertical-axis Darrieus wind turbines (VAWTs) have attracted significant attention in the field of urban wind energy. This interest arises from several advantages, including the simplicity of blade design, the absence of a yaw mechanism, lower noise emissions compared to horizontal-axis wind turbines, an‎d reduced sensitivity to variations in wind direction. Nevertheless, the development of Darrieus turbines faces several challenges, such as the exposure of downstream blades to turbulent flow conditions, negative torque generation, poor self-starting capability, an‎d instability of the angle of attack. Consequently, numerous studies have focused on overcoming these limitations, among which the use of J-shaped blades has emerged as a promising solution for performance enhancement. Previous research has demonstrated that such blade configurations can significantly improve the overall performance of Darrieus turbines. This study investigates an‎d optimizes the performance of a dual Darrieus vertical-axis wind turbine system equipped with J-shaped blades, with a comprehensive analysis of its aerodynamic an‎d economic behavior. The primary objective of this research is to examine the combined effects of rotational direction, blade pitch angle, an‎d the spacing between the two turbines on the system’s performance, as well as to eva‎luate its economic feasibility in the Iranian energy market. To achieve this goal, the Taguchi design of experiments (DoE) method an‎d computational fluid dynamics (CFD) simulations were employed to analyze the flow characteristics. The results indicate that for the first turbine, the optimal performance is achieved with a clockwise (CW) rotation direction, a blade angle of φ = 45°, an‎d a spacing ratio of R₂/R₁ = 2.25. Aerodynamic analysis of the first turbine shows that at a zero-degree azimuth angle, the flow remains attached to the blade surface, resulting in a small but positive initial torque. At an azimuth angle of 120°, the formation of a leading-edge vortex an‎d the occurrence of dynamic stall significantly increase the torque an‎d enhance turbine performance. At 240°, the flow re-stabilizes, an‎d a narrow, uniform wake is directed toward the second turbine. For the second turbine, the accelerated wake flow generated by the first turbine leads to an increase in lift force an‎d an improvement in its performance. Under these conditions, the incoming flow structure becomes more stable an‎d organized. Furthermore, technical analyses reveal that at a spacing of 2.25D, an effective flow acceleration channel is formed, which plays a crucial role in enhancing the performance of the second turbine. Economic assessments demonstrate that both turbines are financially viable projects. For the first turbine, considering an electricity selling tariff of 3,800 IRR/kWh, the payback period is calculated as 1.48 years, an‎d the levelized cost of electricity (LCOE) is estimated at 1,121 IRR/kWh. Similarly, the second turbine exhibits a payback period of 1.45 years an‎d an LCOE lower than the electricity tariff, confirming the system as a cost-effective option for renewable energy generation in Iran. Overall, the results highlight a significant improvement in performance an‎d stability for the dual-turbine system compared to a single-turbine configuration. This research provides a comprehensive eva‎luation of both the technical an‎d economic aspects of Darrieus wind turbines, an‎d its findings can contribute to the optimal design an‎d development of advanced wind energy systems.

توربين بادي عمودمحور , پره‌هاي J-شكل , بهينه‌سازي آيروديناميكي , تحليل اقتصادي توربين بادي , شبيه‌ سازي CFD

Vertical-axis wind turbine , J-shaped blades , aerodynamic optimization , wind turbine economic analysis , CFD simulation

Mohammad amin Valizadeh

Dr.Abolfazl Ahmadi