Wind turbine power improvement utilizing passive flow control with microtab

Ebrahimi, Abbas; Movahhedi, Mohammadreza

doi:10.1016/j.energy.2018.02.144

Cited by 38 publications

(15 citation statements)

References 28 publications

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“…Table 1 lists the geometric parameters of the VGs, while the inflow velocity was set as U = 82 m/s, and the Reynolds number based on the VG height was about 3 × 10 4 . The pressure loss coefficient at the inlet and outlet of the calculation domain was defined as C ∆p , which can be calculated according to Equation (5), where P inlet is the total pressure at the inlet and P outlet the total pressure at the outlet. The pressure difference coefficient reflects the magnitude of pressure difference loss in the computational domain.…”

Section: Computational Setupmentioning

confidence: 99%

“…During the operation of wind turbines, flow separation occurs at the blade root, which reduces the wind turbine efficiency [1]. Flow control technologies, such as VGs [2], plasma flow control [3], microflaps [4], microtabs [5], blowing and suction [6], synthetic jets [7], and flexible walls [8], have been increasingly applied to the design or optimization of wind turbine blades, aiming to improve their aerodynamic performance. Barlas [9] and Johnson [10] compared these flow control methods, while Lin [11] and Wang [12] found that VGs are one of the most effective devices for improving the aerodynamic performance of blades.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of the Effect of Vortex Generator Spacing on Boundary Layer Flow Separation Control

Liu

Zhang

et al. 2019

Applied Sciences

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During the operation of wind turbines, flow separation appears at the blade roots, which reduces the aerodynamic efficiency of the wind turbine. In order to effectively apply vortex generators (VGs) to blade flow control, the effect of the VG spacing (λ) on flow control is studied via numerical calculations and wind tunnel experiments. First, the large eddy simulation (LES) method was used to calculate the flow separation in the boundary layer of a flat plate under an adverse pressure gradient. The large-scale coherent structure of the boundary layer separation and its evolution process in the turbulent flow field were analyzed, and the effect of different VG spacings on suppressing the boundary layer separation were compared based on the distance between vortex cores, the fluid kinetic energy in the boundary layer, and the pressure loss coefficient. Then, the DU93-W-210 airfoil was taken as the research object, and wind tunnel experiments were performed to study the effect of the VG spacing on the lift-drag characteristics of the airfoil. It was found that when the VG spacing was λ/H = 5 (H represents the VG's height), the distance between vortex cores and the vortex core radius were approximately equal, which was more beneficial for flow control. The fluid kinetic energy in the boundary layer was basically inversely proportional to the VG spacing. However, if the spacing was too small, the vortex was further away from the wall, which was not conducive to flow control. The wind tunnel experimental results demonstrated that the stall angle-of-attack (AoA) of the airfoil with the VGs increased by 10 • compared to that of the airfoil without VGs. When the VG spacing was λ/H = 5, the maximum lift coefficient of the airfoil with VGs increased by 48.77% compared to that of the airfoil without VGs, the drag coefficient decreased by 83.28%, and the lift-to-drag ratio increased by 821.86%.

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Section: Computational Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis of the Effect of Vortex Generator Spacing on Boundary Layer Flow Separation Control

Liu

Zhang

et al. 2019

Applied Sciences

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“…Consequently, the overall performance of VAWTs deteriorates, particularly the wind energy utilization ratio 4‐6 . To address the problem of low wind energy utilization ratio of VAWTs, considerable research has been conducted to improve airfoil, optimize the wind turbine structure, and control local flow 7‐9 . Flow control technology can be divided into active flow control and passive flow control.…”

Section: Introductionmentioning

confidence: 99%

Influences of trailing edge split flap on the aerodynamic performance of vertical axis wind turbine

Zhang

et al. 2020

Energy Science & Engineering

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To improve the performance of a 3.5 kW small H‐type vertical axis wind turbine (VAWT) with the airfoil of NACA0015, a design method for installing split flaps at the trailing edge of a blade is proposed. By solving the two‐dimensional URANS equations, the simulation of VAWTs is carried out. The influences of the length (10% c‐30% c), arrangement positions (90% c‐70% c), and deflection angles (10°‐30°) of the split flaps on the performance of VAWT are determined by orthogonal design when Reynolds number is 2 × 105 and 1 < TSR < 3. In accordance with the influence degrees of these parameters and adopting the maximum wind energy utilization ratio CPmax and the maximum efficient operating range Δλmax as research objectives, the optimum flap length is determined as 22% c, the optimum deflection angle is 10°, and the optimum arrangement position is 92% c. Further studies show that the CPmax is increased by 5.8% and its Δλmax is increased by 25.9% after installing split flaps. Meanwhile, split flaps can change the Kutta‐Joukowsky trailing edge boundary condition, which increases the flow circulation around the airfoil. Also, split flaps can increase the positive pressure difference in the upwind area and reduce the negative pressure difference in the downwind area, which significantly improves the aerodynamic performance of VAWTs.

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“…According to the latest data from the Global Wind Energy Council [1], as of 2017, the total installed capacity of the global wind power market has reached 539.6 GW, and wind power has become the third largest power source in the world. However, during the operation of wind turbines, the blade root is prone to flow separation, which decreases the power of wind turbines [2][3][4][5][6]. Many novel methods have been proposed for improving the performance of wind turbine blades in recent years, such as vortex generators (VGs) [7], microflaps [8], microtabs [4], blowing and suction [9], synthetic jets [10], flexible wall [11], and plasma actuators [12].…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Analysis of the Effect of Vortex Generator Height on Vortex Characteristics and Airfoil Aerodynamic Performance

Yang

Wang

2019

Energies

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To explore the effect of the height of vortex generators (VGs) on the control effect of boundary-layer flow, the vortex characteristics of a plate and the aerodynamic characteristics of an airfoil for VGs were studied by both wind tunnel experiments and numerical methods. Firstly, the ratio of VG height (H) to boundary layer thickness (δ) was studied on a flat plate boundary layer; the values of H are 0.1δ, 0.2δ, 0.5δ, 1.0δ, 1.5δ, and 2.0δ. Results show that the concentrated vortex intensity and VG height present a logarithmic relationship, and vortex intensity is proportional to the average kinetic energy of the fluid in the height range of the VG. Secondly, the effects of height on the aerodynamic performance of airfoils were studied in a wind tunnel using three VGs with H = 0.66δ, 1.0δ, and 1.33δ. The stall angle of the airfoil with and without VGs is 18° and 8°, respectively, so the VGs increase the stall angle by 10°. The maximum lift coefficient of the airfoil with VGs increases by 48.7% compared with the airfoil without VGs, and the drag coefficient of the airfoil with VGs is 84.9% lower than that of the airfoil without VGs at an angle of attack of 18°. The maximum lift–drag ratio of the airfoil with VGs is lower than that of the airfoil without VGs, so the VGs do not affect the maximum lift–drag ratio of the airfoil. However, a VG does increase the angle of attack of the best lift–drag ratio.

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Wind turbine power improvement utilizing passive flow control with microtab

Cited by 38 publications

References 28 publications

Analysis of the Effect of Vortex Generator Spacing on Boundary Layer Flow Separation Control

Analysis of the Effect of Vortex Generator Spacing on Boundary Layer Flow Separation Control

Influences of trailing edge split flap on the aerodynamic performance of vertical axis wind turbine

Experimental and Numerical Analysis of the Effect of Vortex Generator Height on Vortex Characteristics and Airfoil Aerodynamic Performance

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