Enhancing vertical axis wind turbine by dynamic stall control using synthetic jets

Yen, Joshua; Ahmed, Noor A.

doi:10.1016/j.jweia.2012.12.015

Cited by 102 publications

(35 citation statements)

References 38 publications

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“…Because of the cyclic movement of the wind turbine, even though the wind flow is uniform, the relative velocity of the wind blade and flow direction varies during each cycle. At angles of attack beyond the stall condition, flow separation occurs around the airfoil, which may be a major factor in reducing the torque developed; in VAWT, a dynamic stall implies a defect of the power coefficient at low blade speed ratios (λ) for blade angles of attack of ±50˚ [10].…”

Section: Introductionmentioning

confidence: 99%

Numerical Performance Assessment of a Flapping-Type Vertical Axis Wind Turbine with Chebyshev-Dyad Linkage

Alam¹,

Hirahara²

2017

SGRE

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In order to harness wind energy with high coefficients, horizontal axis wind turbines (HAWT), like propeller-type wind turbines, have an advantage in terms of practical utilization because of their scale merit. However, large size and high tip-speed ratio are inherently related to material strength problems and low frequency noise emissions to the environment. In contrast to HAWT, we will discuss a flapping-type turbine driven at low speed. The flapping turbine works using lift force like the HAWT, but employs a new wind turbine concept in the present report. The concept involves the unique flapping motion of a wind blade mounted on a Chebyshev-dyad linkage by which the wing transforms wind energy into mechanical rotation. Both static and dynamic numerical estimates are developed to optimize all fundamental parameters of this linkage in order to obtain the desired torque. In this paper, the results of primitive optimization for determining the fundamental characteristics of motion and the trajectory of the wind turbine blade are demonstrated in order to obtain smooth rotation of the generator-driving shaft. It is also shown that the present turbine can be driven at low speed with a suitable energy conversion rate. Moreover, the practicality of operating slow flapping-type wind turbines is demonstrated, focusing on usage near residential areas or, e.g., on rooftops owing to lower noise. The feasibility of "figure eight" trajectory diversity is discussed along with geometrical parameters. Assuming one-blade motion with a variable trajectory for optimization, the smooth motion and required torque at slow rotation speeds are studied. Keywords

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Section: Introductionmentioning

confidence: 99%

Numerical Performance Assessment of a Flapping-Type Vertical Axis Wind Turbine with Chebyshev-Dyad Linkage

Alam¹,

Hirahara²

2017

SGRE

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“…Hence, for a flow control method, it is important to provide the blade with both, good static and dynamic, aerodynamic perofmance. Various flow control methods have been investigated to enhance wind turbine blade performance, including trailing edge flaps [5], microtabs [6,7], vortex generators [8], blowing jets [9,10], circulation control [11], Gurney flaps [11], synthetic jets [12], and plasma actuators [13]. Hanns et al [10] carried out an experimental study to explore constant blowing as a flow control concept for wind turbine blades.…”

Section: Introductionmentioning

confidence: 99%

“…However, the results also indicated that at high-wind speed conditions where the flow separates, the trailing-edge blowing and the Gurney flap both became ineffective in increasing the power output. Yen and Ahmed [12] implemented synthetic jets to study the wind turbine dynamic stall control and demonstrated that synthetic jets could improve low speed vertical-axis wind turbine performance but without substantially alleviating stall separation. Greenblatt et al [13] experimentally measured the effects of plasma pulsation on dynamic stall control on the upwind half of a turbine and also limited phase-locked particle image velocimetry measurements were performed under baseline as well as two controlled conditions.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Stall Control on the Wind Turbine Airfoil via a Co-Flow Jet

Qiao

2016

Energies

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Dynamic stall control of a S809 airfoil is numerically investigated by implementing a co-flow jet (CFJ). The numerical methods of the solver are validated by comparing results with the baseline experiment as well as a NACA 6415-based CFJ experiment, showing good agreement in both static and dynamic characteristics. The CFJ airfoil with inactive jet is simulated to study the impact that the jet channel imposes upon the dynamic characteristics. It is shown that the presence of a long jet channel could cause a negative effect of decreasing lift and increasing drag, leading to fluctuating extreme loads in terms of drag and moment. The main focus of the present research is the investigation of the dynamic characteristics of the CFJ airfoil with three different jet momentum coefficients, which are compared with the baseline, giving encouraging results. Dynamic stall can be greatly suppressed, showing a very good control performance of significantly increased lift and reduced drag and moment. Analysis of the amplitude of variation in the aerodynamic coefficients indicates that the fluctuating extreme aerodynamic loads are significantly alleviated, which is conducive to structural reliability and improved life cycle. The energy consumption analysis shows that the CFJ concept is applicable and economical in controlling dynamic stall.

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“…By applying this approach of dynamic stall control, Yen and Ahmed [6] showed synthetic jet actuation to be effective for a vertical axis wind turbine (VAWT). By the stall-controlled approach, the system may sustain its stable operation …”

Section: Introductionmentioning

confidence: 99%

Experiments on the Performance of Small Horizontal Axis Wind Turbine with Passive Pitch Control by Disk Pulley

Chen

Shiah

2016

Energies

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Abstract:The present work is to design a passive pitch-control mechanism for small horizontal axis wind turbine (HAWT) to generate stable power at high wind speeds. The mechanism uses a disk pulley as an actuator to passively adjust the pitch angle of blades by centrifugal force. For this design, aerodynamic braking is caused by the adjustment of pitch angles at high wind speeds. As a marked advantage, this does not require mechanical brakes that would incur electrical burn-out and structural failure under high speed rotation. This can ensure the survival of blades and generator in sever operation environments. In this paper, the analysis uses blade element momentum theory (BEMT) to develop graphical user interface software to facilitate the performance assessment of the small-scale HAWT using passive pitch control (PPC). For verification, the HAWT system was tested in a full-scale wind tunnel for its aerodynamic performance. At low wind speeds, this system performed the same as usual, yet at high wind speeds, the equipped PPC system can effectively reduce the rotational speed to generate stable power.

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Enhancing vertical axis wind turbine by dynamic stall control using synthetic jets

Cited by 102 publications

References 38 publications

Numerical Performance Assessment of a Flapping-Type Vertical Axis Wind Turbine with Chebyshev-Dyad Linkage

Numerical Performance Assessment of a Flapping-Type Vertical Axis Wind Turbine with Chebyshev-Dyad Linkage

Dynamic Stall Control on the Wind Turbine Airfoil via a Co-Flow Jet

Experiments on the Performance of Small Horizontal Axis Wind Turbine with Passive Pitch Control by Disk Pulley

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