On the influence of virtual camber effect on airfoil polars for use in simulations of Darrieus wind turbines

Rainbird, John M.; Bianchini, Alessandro; Balduzzi, Francesco; Peiró, Joaquim; Graham, John M.; Ferrara, Giovanni; Ferrari, Lorenzo

doi:10.1016/j.enconman.2015.09.053

Cited by 88 publications

(29 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Migliore et al 71 illustrated that the flow curvature effects became more pronounced at large ratio. The blade performance will be modified due to the curvature effects and it must be considered when translating conventional aerofoil data for VAWT applications, as confirmed by a study performed by Rainbird et al 72 . Figure 7 Schematic drawing of curvature effects for symmetric blades moving in a curvilinear flow 71 Due to the orientation of the virtual camber, an additional normal force acts toward the centre of rotation and the normal force is increased during the upstream pass and decreased during the downstream pass.…”

Section: Curvaturementioning

confidence: 86%

A review of H-Darrieus wind turbine aerodynamic research

Ingram

Dominy

2019

Proceedings of the Institution of Mechanical Engineers, Part C:

View full text Add to dashboard Cite

The H-Darrieus vertical axis turbine is one of the most promising wind energy converters for locations where there are rapid variations of wind direction, such as in the built environment. The most challenging considerations when employing one of these usually small machines are to ensure that they self-start and to maintain and improve their efficiency. However, due to the turbine's rotation about a vertical axis, the aerodynamics of the turbine are more complex than a comparable horizontal axis wind turbine and our knowledge and understanding of these turbines falls remains far from complete. This paper provides a detailed review of past and current studies of the H-Darrieus turbine from the perspective of design parameters including turbine solidity, blade profile, pitch angle, etc. and particular focus is put on the crucial challenge to design a turbine that will self-start. Moreover, this paper summarizes the main research approaches for studying the turbine in order to identify successes and promising areas for future study.

show abstract

Section: Curvaturementioning

confidence: 86%

A review of H-Darrieus wind turbine aerodynamic research

Ingram

Dominy

2019

Proceedings of the Institution of Mechanical Engineers, Part C:

View full text Add to dashboard Cite

show abstract

“…The most popular choice of airfoils for Darrieus turbines are symmetrical NACA profiles such as NACA 0015, 0018, and 0021, as they are experimentally validated for the range of Re that a VAWT typically experiences while in operation. Though it seems logical and efficient to use symmetrical airfoils as the suction and pressure side are reversed during the upwind and downwind rotation, the cambered airfoils are preferred from the self-starting perspective, especially for the fixed pitch VAWT as evaluated by Rainbird [28]. The airfoils should generate sufficient lift at low Re of 10 3 to 10 4 to overcome the resistive and inertial torque of the turbine to self-start.…”

Section: Camber and Symmetric Airfoilsmentioning

confidence: 99%

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

et al. 2019

View full text Add to dashboard Cite

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...

show abstract

“…Symmetrical NACA 0015 airfoil with a 15% thickness to chord ratio has been chosen for this study. It is an indisputable fact that a cambered airfoil is preferable for the VAWT, due to the curved nature of the airfoil as reported by [39][40][41]. However, VAWT researchers have used one of the original NACA four digit series airfoil sections, usually either a NACA 0012 or a NACA 0015 section.…”

Section: Selection Of Airfoilmentioning

confidence: 99%

Design and Testing of a Novel Building Integrated Cross Axis Wind Turbine

et al. 2017

View full text Add to dashboard Cite

Abstract:The prospect of harnessing wind energy in urban areas is not promising owing to low wind speeds and the turbulence caused by surrounding obstacles. However, these challenges can be overcome through an improved design of wind turbine that can operate efficiently in an urban environment. This paper presents a novel design of a building integrated cross axis wind turbine (CAWT) that can operate under dual wind direction, i.e., horizontal wind and vertical wind from the bottom of the turbine. The CAWT consists of six horizontal blades and three vertical blades for enhancing its self-starting behavior and overall performance. The study employed a mock-up building model with gable rooftop where both of the developed CAWT and the conventional straight-bladed vertical axis wind turbine (VAWT) are mounted and tested on the rooftop. The height of the CAWT and the VAWT above the rooftop was varied from 100 to 250 mm under the same experimental conditions. The results obtained from the experimental study showed that there is significant improvement in the coefficient of power (C p ) and self-starting behavior of the building integrated CAWT compared to the straight-bladed VAWT. At 100 mm height, the C p,max value of the CAWT increased by 266%, i.e., from 0.0345 to 0.1263, at tip speed ratio (TSR) (λ) of 1.1 and at wind speed of 4.5 m/s. Similar improvements in performance are also observed for all condition of CAWT heights above the rooftop where the CAWT outperformed the straight-bladed VAWT by 196%, 136% and 71% at TSR of 1.16, 1.08, and 1.12 for Y = 150, 200, and 250 mm, respectively. Moreover, the CAWT performs better at 10 • pitch angle of the horizontal blade compared to other pitch angles.

show abstract

On the influence of virtual camber effect on airfoil polars for use in simulations of Darrieus wind turbines

Cited by 88 publications

References 31 publications

A review of H-Darrieus wind turbine aerodynamic research

A review of H-Darrieus wind turbine aerodynamic research

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

Design and Testing of a Novel Building Integrated Cross Axis Wind Turbine

Contact Info

Product

Resources

About