Strategies for Enhancing the Low Wind Speed Performance of H-Darrieus Wind Turbine—Part 1

Abstract

Small wind turbines are key devices for micro generation in particular, with a notable contribution to the global wind energy sector. Darrieus turbines, despite being highly efficient among various types of vertical axis turbines, received much less at tention due to their starting characteristics and poor performance in low wind speeds. Radically different concepts are proposed as a potential solution to enhance the performance of Darrieus turbine in the weak wind flows, all along the course of Darrieus turbine development. This paper presents a comprehensive review of proposed concepts with the focus set on the low wind speed performance and critically assessing their applicability based on economics, reliability, complexity, and commercialization aspects. The study is first of its kind to consolidate and compare various approaches studied on the Darrieus turbine with the objective of increasing performance at low wind. Most of the evaluated solutions demonstrate better performance only in the limited tip speed ratio, though they improve the low wind speed performance. Several recommendations have been developed based on the evaluated concepts, and we concluded that further critical research is required for a viable solution in making the Darrieus turbine a low speed device.commercially exploited for large scale power production [2]. The VAWTs are preferred for small scale power generation due to their unique advantages such as Omni directionality [3], lower manufacturing cost, the benefit of a generator on the ground level, and low noise. As VAWTs are preferred for roof top installations, the skewed flow must be accounted for. Wind tunnel test on both HAWT and VAWT shows that VAWT perform better than HAWT in skewed flow, even up to 30 • . Among VAWTs, the turbines are categorized as lift and drag based. The Savonius turbines are based on the drag difference between the rotating blades. Despite its lower efficiency and maximum power coefficient of 0.18 [4], these types of turbines are preferred for low wind conditions due to high dynamic moment as demonstrated in a recent study [5]. The lift based Darrieus turbines are preferred for moderate wind speeds with the power coefficient of 0.35~0.38 [6]. Since the small wind turbines are often installed in the locations of power demand [7] rather than optimum wind speed condition. As high wind sites are exploited to the fullest, these turbines find their locations that have an average wind speed of 4~6 m/s. Darrieus turbines are notoriously bad performers in these wind speeds due to their non-self-starting nature and very low torque due to the aerodynamics that are associated with the Darrieus rotor configuration.The search for a feasible solution to enable a Darrieus turbine to generate optimal power at low wind speed continue for decades. Over these years, countless efforts have been made through experimental, computational and field tests to achieve significant progress in understanding self-starting physics of Darrieus turbine. These at tempts substantially improv...

Performance Analysis of a H-Darrieus Wind Turbine for a Series of 4-Digit NACA Airfoils

“…In the case of a wind turbine rotor at TSR of 2 with thinner airfoils (NACA 0012 and NACA 0015), the oscillatory nature of aerodynamic blade loads seems to be more visible in comparison with thicker airfoils (NACA 0018 and NACA 0021). As mentioned above, the NACA 0012 airfoil exhibits a sudden drop in the lift characteristic in comparison with thicker airfoils that show a smooth drop in the lift [64,68]. Moreover, the hysteretic behavior of the thick symmetrical NACA 00XX airfoils at stall is delated in comparison with thin profiles [69].…”

Experimental Assessment of Suitability of Darrieus and Savonius Turbines for Obtaining Wind Energy from Passing Vehicles

“…For this reason, it is used in conjunction with a Savonius turbine [51,52] or is accelerated with an additional electric motor. Over time, many modifications have been developed to eliminate this problem [53][54][55]. Darrieus, Figure 10b).…”

Design and implementation of smart integrated hybrid Solar-Darrieus wind turbine system for in-house power generation

“…However, this design was the turbine that was patented in 1931, where the evolution and innovation of the technology has brought upon various designs such as the H-Darrieus and the helical Darrieus. The turbine has good efficiency but low reliability from the large torque ripple and cyclic stress produced on the tower [11].…”