A numerical study on the influence of cavity shape on synthetic jet performance

Ziadé, Paul; Feero, Mark A.; Sullivan, Pierre E.

doi:10.1016/j.ijheatfluidflow.2018.10.001

Cited by 23 publications

(15 citation statements)

References 15 publications

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“…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]. A comparison of these methods was performed by Barlas [13] and Johnson [14] to illustrate their efficiency.…”

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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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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“…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%

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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“…Specifically, flow separation on the airfoil suction surface close to the blade root occurs during the operation of the wind turbine, reducing the capture power of the wind turbine [2]. To address this, researchers have proposed many methods to suppress flow separation for airfoil blades including microflaps [3], blowing and suction [4], microtabs [5], flexible walls [6], synthetic jets [7,8], plasma actuators [9,10], and VG [11,12]. Barlas [13] and Johnson [14] compared and analyzed the flow control effects of each of these different methods.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Analysis of the Effect of Vortex Generator Installation Angle on Flow Separation Control

Liu

Zhang

et al. 2019

Energies

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In order to explore the effect of the installation angle of vortex generator (VG) on boundary-layer flow control, the vortex characteristics of plate VG and their effect on the aerodynamic characteristics of an airfoil was studied numerically and using wind tunnel experiments. The effects of five VG installation angles (β) of 10°, 15°, 20°, 25°, and 30° on the characteristics of vortices were studied. The results show that the strength of vortices on the leeward side of VG increases with an increased installation angle until, eventually, the vortex core breaks down. During the downstream development of the VG leading-edge separation vortices, these vortices deviate in the radial direction. The larger the installation angle, the larger this deviation distance in the radial direction becomes. The effects of installation angle on the aerodynamic performance of airfoils were studied in a wind tunnel using the same five VG installation angles. The results show that VG can delay flow separation on the airfoil suction surface, thereby increasing lift and reducing drag. The stall angle of the airfoil with VG was increased by 10°. When the installation angle of the VG was 20°, the maximum lift coefficient of airfoil increased by 48.77%. For an airfoil angle of attack (AoA) of 18°, the drag of the airfoil decreased by 88%, and the lift-drag ratio increased by 1146.04%. Considering the best overall distribution of lift-drag ratio, the positive effect of the VG was found to be when β = 20° and the worst VG effectiveness was observed at β = 30°.

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A numerical study on the influence of cavity shape on synthetic jet performance

Cited by 23 publications

References 15 publications

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

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

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

Experimental and Numerical Analysis of the Effect of Vortex Generator Installation Angle on Flow Separation Control

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