Experimental investigation of an optimised pitch control for a vertical‐axis turbine

Abbaszadeh, Shokoofeh; Hoerner, Stefan; Maı̂tre, Thierry; Leidhold, Roberto

doi:10.1049/iet-rpg.2019.0309

Cited by 13 publications

(9 citation statements)

References 31 publications

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“…Beside more fundamental research on the flow characteristics themselves, numerous strategies have been pursued to overcome the negative effects of dynamic stall in these turbines, such as adaptive blowing (Müller-Vahl et al 2014) or plasma actuators (Greenblatt et al 2014). A common approach is to balance the rotor blades during the rotation with active or passive pitch motion of the blades in order to avoid deep dynamic stall, as shown by Pawsey et al (2002), Lazauskas and Kirke (2012), Mauri et al (2014), Liang et al (2016), Chatellier et al (2018) or Abbaszadeh et al (2019). Strom et al (2016) introduced a control of the angular velocity based on the azimuth angle that can significantly improve the performance of a two-blade VAWT.…”

Section: Introductionmentioning

confidence: 99%

Darrieus vertical-axis water turbines: deformation and force measurements on bioinspired highly flexible blade profiles

et al. 2020

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The characteristics of the fluid-structure interaction on the flexible blades of a horizontal-axis water turbine are studied; this bioinspired technology features mechanical simplicity, performance and lifetime improvement, and low fish impact risk, all characteristics of a truly sustainable renewable energy exploitation. A surface-tracking method synchronized with force measurements was applied on a surrogate model of single-bladed, vertical-axis water turbine in a water channel. This allows for the characterization of the structural deformations and their link to the hydrodynamic forces, over a large range of turbine designs and operating points. It is shown that the phase angles of the maxima in blade deformation coincide with those of the load maxima on a rigid blade in identical flow conditions. The influence of the turbine's tip/speed ratio on the blade deformation and blade load is investigated. With the chosen blade design, hydrofoil deformation is found to be maximum in the operating points where the performance improvement is maximized (k o = 0.3). With lower values of reduced frequency (corresponding to lower rotation speed), fluid-induced forces dominate the fluid-structure interaction. Conversely, at higher frequencies, structural inertia dominates the interaction, and blade deformation is again reduced. Results suggest that the optimal blade rigidity may depend on the operating point; nevertheless the potential of the flexible-blade design is demonstrated through clear linking of fluid-induced forces and blade deformation in the complex flow conditions of the Darrieus water turbine.

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Section: Introductionmentioning

confidence: 99%

Darrieus vertical-axis water turbines: deformation and force measurements on bioinspired highly flexible blade profiles

et al. 2020

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“…One is to control the angle of incidence of the rotor blades by active or passive pitch mechanisms on rigid blades. This most extensively studied method provides high improvements in the turbine efficiency and lowers the alternating load peaks, as reported by Lazauskas and Kirke 2012 [16], Khalid et al 2013 [17], Mauri et al 2014 [18] or Abbaszadeh et al 2019 [19]. However, blade pitching requires complex mechanisms and adds an additional source of failure to the systems, reducing simplicity and robustness.…”

Section: State Of Science and Technologymentioning

confidence: 93%

Cross-Flow Tidal Turbines with Highly Flexible Blades—Experimental Flow Field Investigations at Strong Fluid–Structure Interactions

et al. 2021

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Oscillating hydrofoils were installed in a water tunnel as a surrogate model for a hydrokinetic cross-flow tidal turbine, enabling the study of the effect of flexible blades on the performance of those devices with high ecological potential. The study focuses on a single tip-speed ratio (equal to 2), the key non-dimensional parameter describing the operating point, and solidity (equal to 1.5), quantifying the robustness of the turbine shape. Both parameters are standard values for cross-flow tidal turbines. Those lead to highly dynamic characteristics in the flow field dominated by dynamic stall. The flow field is investigated at the blade level using high-speed particle image velocimetry measurements. Strong fluid–structure interactions lead to significant structural deformations and highly modified flow fields. The flexibility of the blades is shown to significantly reduce the duration of the periodic stall regime; this observation is achieved through systematic comparison of the flow field, with a quantitative evaluation of the degree of chaotic changes in the wake. In this manner, the study provides insights into the mechanisms of the passive flow control achieved through blade flexibility in cross-flow turbines.

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“…Numerous studies have investigated methods to overcome these effects, which doubtlessly hinder large-scale industrial applications. One approach is to continually vary the pitch angle of the blades using mechanical systems in order to control their angle of attack (Abbaszadeh et al 2019;Liang et al 2016;Mauri et al 2014;Zhang et al 2014;Lazauskas and Kirke 2012;Khalid et al 2013). Another approach, termed angular velocity control, uses phases of rotational acceleration and deceleration in order to control the angle of attack by adjustment of the tangential velocity (Strom et al 2016).…”

Section: Dynamic Stall and Turbine Efficiencymentioning

confidence: 99%

Passive flow control mechanisms with bioinspired flexible blades in cross-flow tidal turbines

et al. 2021

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State-of-the-art technologies for wind and tidal energy exploitation focus mostly on axial turbines. However, cross-flow hydrokinetic tidal turbines possess interesting features, such as higher area-based power density in array installations and shallow water, as well as a generally simpler design. Up to now, the highly unsteady flow conditions and cyclic blade stall have hindered deployment at large scales because of the resulting low single-turbine efficiency and fatigue failure challenges. Concepts exist which overcome these drawbacks by actively controlling the flow, at the cost of increased mechatronical complexity. Here, we propose a bioinspired approach with hyperflexible turbine blades. The rotor naturally adapts to the flow through deformation, reducing flow separation and stall in a passive manner. This results in higher efficiency and increased turbine lifetime through decreased structural loads, without compromising on the simplicity of the design. Graphic abstract

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Experimental investigation of an optimised pitch control for a vertical‐axis turbine

Cited by 13 publications

References 31 publications

Darrieus vertical-axis water turbines: deformation and force measurements on bioinspired highly flexible blade profiles

Darrieus vertical-axis water turbines: deformation and force measurements on bioinspired highly flexible blade profiles

Cross-Flow Tidal Turbines with Highly Flexible Blades—Experimental Flow Field Investigations at Strong Fluid–Structure Interactions

Passive flow control mechanisms with bioinspired flexible blades in cross-flow tidal turbines

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