A high performance airfoil with moving surface boundary-layer control

Modi, V. J.; Munshi, S. R.; Bandyopadhyay, G.; Yokomizo, T.

doi:10.2514/6.1996-3445

Cited by 7 publications

(12 citation statements)

References 5 publications

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“…5, a symmetrical 16% thick basic Joukowsky airfoil attains its maximum lift at a 16 deg and experiences leading-edge stall at a 18 deg when tested in a wind tunnel at a Reynolds number of 2.31 10 5 . As a result, such angles of attack are used as a reference here.…”

Section: Resultsmentioning

confidence: 99%

“…The application of a smooth or splined rotating cylinder embedded in the airfoil surface to prevent or delay separation, as extensively studied by Modi et al, 5 has shown a signi cant delay in the stall angle and an increase in the lift coef cient at high angles of attack. The Kasper wing (see Ref.…”

Section: Nomenclaturementioning

confidence: 99%

“…Such a condition was not explored in Hurley's 14 model. 5) In the experimentalstudy,Hurley 14 proposedthe useof blowing high-speed air from a slot located near the leading edge of the upper boundary to achieve ow reattachment. Such a usage of external source of ow was never incorporatedin Hurley's theoreticalmodel.…”

Section: Nomenclaturementioning

confidence: 99%

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Theoretical Model for Airfoils to Suppress Leading-Edge Separation

Yeung

2001

AIAA Journal

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A theoretical study is presented for an airfoil tted with an upper-surface ap undergoing leading-edge stall. Instead of delaying or circumventing ow separation, ow is allowed to separate tangentially from an airfoil with a portion of its suction side truncated. The separation streamline is, thus, made to reattach smoothly at the tip of a streamlined forward-facing ap, which joins the airfoil tangentially to eschew any unnecessary stagnated ow. Different from conventional free-streamline models, the pressure along the bounding streamline is not assumed constant in the present model. Rather, nite velocities (whose values are unknown a priori) are achieved at separation, reattachment, and the trailing edge of the airfoil by utilizing mathematical singularities such as a vortex located inside the hollow airfoil. Furthermore, the condition of a nite pressure gradient at reattachment as deduced from available experimental data is proposed. The resulting lift is found to be larger than that of the basic Joukowsky airfoil for a wide range of angle of attack because the bounding streamline increases the airfoil camber. The modi ed pro le may be considered as a new family of Joukowsky airfoil. Nomenclature= radius of circle in Z 1 plane R V = radial distance of vortex r = real constant U, V = uniform upstream velocities W = complex velocity x, y = coordinates Z , Z 1 , Z 1,0 , = complex numbers Z 2 , Z 3 , Z 4 Z 4, , Z 4, = complex numbers a = angle of attack a , b , d , h 0 , = angles h , h , r C 1 , C 2 = vortex strengths e , l = positive constants f = complex plane K = positive constant q = density

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Section: Resultsmentioning

confidence: 99%

Section: Nomenclaturementioning

confidence: 99%

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Theoretical Model for Airfoils to Suppress Leading-Edge Separation

Yeung

2001

AIAA Journal

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“…As a typical active flow control technique, the moving surface boundary layer control (MSBLC) can be traced back to the last century (Ericsson 1994) and has been demonstrated to be an effective method for reducing drag of a bluff body (Kumar et al 2011;Korkischko and Meneghini 2012;Schulmeister et al 2017) and increasing lift of an airfoil (Modi et al 1998;Ericsson 1994) by means of a moving element (as shown in Fig. 1), such as rotating control cylinders, and drawn much attention because of its significant control effect.…”

Section: Introductionmentioning

confidence: 99%

Flow control over a circular cylinder using virtual moving surface boundary layer control

et al. 2019

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Flow control study of a circular cylinder is carried out using symmetric dielectric barrier discharge (DBD) plasma actuators at the Reynolds number of 10,000. Here, two symmetric DBD plasma actuators are located at the top and bottom of the circular cylinder, respectively, each of which induces pairs of counter-rotating starting vortices on both sides of exposed electrodes. The downstream starting vortices soon take the form of a wall jet along the freestream direction. On the other hand, the upstream starting vortices interact with the incoming flow remain for some time, bringing in high momentum from the freestream to near-wall region, enabling the boundary layer to withstand the adverse pressure gradient and suppressing the separation around the circular cylinder. The rotating vortical structures around the circular cylinder created by the plasma actuators lead to a reduction in the drag coefficient of up to 25%, providing a similar effect to moving surface boundary layer control (MSBLC). This configuration of symmetric DBD plasma actuator, which is studied for the first time in this investigation, is, therefore, called virtual MSBLC. Our results also indicated that the control effect of virtual MSBLC can be enhanced with an increase in the momentum coefficient of plasma jet. Unlike traditional MSBLC devices, the virtual MSBLC based on symmetric DBD plasma actuators do not have profile drag and are without complicated mechanical systems.

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“…Although generating a source of negative vorticity may be more difficult than producing a sink of positive vorticity, a variety of techniques for affecting sources of negative vorticity have been developed within dynamic stall studies, including: wall-normal jet actuation [39,40,45], spanwise blowing [21,119] and rotating cylinders in airfoils [75,5,134].…”

Section: Future Workmentioning

confidence: 99%

Understanding and controlling vorticity transport in unsteady, separated flows

Akkala¹

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A high performance airfoil with moving surface boundary-layer control

Cited by 7 publications

References 5 publications

Theoretical Model for Airfoils to Suppress Leading-Edge Separation

Theoretical Model for Airfoils to Suppress Leading-Edge Separation

Flow control over a circular cylinder using virtual moving surface boundary layer control

Understanding and controlling vorticity transport in unsteady, separated flows

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