Control of Poststall Airfoil Using Leading-Edge Pulsed Jets

Hipp, Kyle D.; Walker, Michael M.; Benton, Stuart I.; Bons, Jeffrey P.

doi:10.2514/1.j055223

Cited by 15 publications

(5 citation statements)

References 25 publications

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“…At post-stall angles of attack (α 8 • ), applying control can reattach the flow with an approximate 50% increase in lift and 50% decrease in drag. Pulsed jets have also been utilized recently by Hipp et al [9] to reattach flow separated from the leading edge of an NACA 64 3 -618 airfoil at Re = 64, 000.…”

Section: Introductionmentioning

confidence: 99%

“…As a means to prevent or delay separation, active and passive flow control actuators can be utilized to introduce perturbations to the flow field [3][4][5][6]. Active flow control is defined by the addition of external energy to the flow, and can be performed with an assortment of flow control actuators [6], including steady and unsteady blowing/suction [1,7,8], pulsed jets [9], synthetic jets [10], sweeping jets [11,12], plasma actuators [13,14], thermal actuators [15,16], and vortex generator jets [17][18][19][20]. Passive flow control devices modify the flow without external energy input and include, leading edge modification [21,22], vortex generators [23,24], and riblets [25,26].…”

Section: Introductionmentioning

confidence: 99%

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Effects of Wall-Normal and Angular Momentum Injections in Airfoil Separation Control

Munday

Taira

2018

AIAA Journal

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The objective of this computational study is to quantify the influence of wall-normal and angular momentum injections in suppressing laminar flow separation over a canonical airfoil. Open-loop control of fully separated, incompressible flow over a NACA 0012 airfoil at α = 9 • and Re = 23, 000 is examined with large-eddy simulations. This study independently introduces wall-normal momentum and angular momentum into the separated flow using swirling jets through model boundary conditions. The response of the flow field and the surface vorticity fluxes to various combinations of actuation inputs are examined in detail. It is observed that the addition of angular momentum input to wall-normal momentum injection enhances the suppression of flow separation. Lift enhancement and suppression of separation with the wall-normal and angular momentum inputs are characterized by modifying the standard definition of the coefficient of momentum. The effect of angular momentum is incorporated into the modified coefficient of momentum by introducing a characteristic swirling jet velocity based on the non-dimensional swirl number. With this single modified coefficient of momentum, we are able to categorize each controlled flow into separated, transitional, and attached flows. Nomenclature A = Planform area Aj = Actuator jet area c = Chord length CD = Coefficient of drag CL = Coefficient of lift Cµ = Coefficient of momentum C * µ = Modified coefficient of momentum Fx = Drag force Fy = Lift force Gn = Wall-normal momentum flux G θ = Tangential momentum flux lz = Spanwise extent M∞ = Freestream Mach number n = Wall-normal unit vector Nact = Number of actuators p = Pressure p = Time-average pressure p∞ = Freestream pressure Q = Q criteria r = Radial direction ra = Radius of actuator Re = Reynolds number RMS = Root mean square S = Swirl number t = Time u = (ux, uy, uz) = Velocity (streamwise, vertical, spanwise) u = (u x , u y , u z ) = Velocity fluctuation (streamwise, vertical, spanwise) u = (ux, uy, uz) = Time-average velocity (streamwise, vertical, spanwise) Uc = Convective velocity uj = Characteristic jet velocity u * j = Modified characteristic jet velocity un = Wall-normal actuator velocity u θ = Azimuthal/rotational actuator velocity uτ = Friction velocity U∞ = Freestream velocity x = (x, y, z) = Spatial coordinates (streamwise, vertical, spanwise) x + = (x + , y + , z + ) = Spatial coordinates in wall units Greek symbols α = Angle of attack, deg Γn = Wall-normal circulation of actuator jet ν = Kinematic viscosity ρ∞ = Freestream density Σ = Diffusive vorticity flux (σx, σy, σz) = Time-average wall-normal diffusive vorticity flux (streamwise, vertical, spanwise) τxy = Spanwise Reynolds stress ω = (ωx, ωy, ωz) = Vorticity (streamwise, vertical, spanwise)

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of Wall-Normal and Angular Momentum Injections in Airfoil Separation Control

Munday

Taira

2018

AIAA Journal

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“…Schematics of: (a) fluidic oscillators, 102 (b) wall-normal pulsed jets, 108 (c) hybrid SJA, 119 (d) DBD actuators, 129 (e) moving walls, 13 and (f) deforming wall patch. 155 …”

Section: Classification and Description Of Flow Control Methodsmentioning

confidence: 99%

“…The performance of active flow control on a laminar airfoil at a post-stall AoA is evaluated experimentally using discrete, wall-normal pulsed jets (Figure 4(b)) by Hipp et al 108 It is observed that, for a given blowing ratio, as the duty cycle is reduced, the lift coefficient increases. On the other hand, at extended jet-off times, a complete separation may reoccur.…”

Section: Active Flow Controlmentioning

confidence: 99%

Current state and future trends in boundary layer control on lifting surfaces

Svorcan

Wang

Griffin

2022

Advances in Mechanical Engineering

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Successful flow control may bring numerous benefits, such as flow stabilization, flow reattachment, separation delay, drag reduction, lift increase, aerodynamic performance improvement, energy efficiency increase, shock delay or weakening, noise reduction, etc. For these purposes, many different flow control devices, which can be classified as passive, semi-active and active, have been designed and tested. This review paper aims to highlight the most promising and commonly employed boundary layer control methods as well as outline their potential in specific applications in aerospace and energy engineering. Referenced studies, performed on various geometries (flat plates, channels, airfoils, wings, blades, cylinders), are primarily numerical or experimental. Although enhanced aerodynamic performance is achieved in many cases, further research is required to draw general conclusions. This paper aims to demonstrate that, in the future, we may expect further developments of flow control actuators, as well as their increased application.

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“…Therefore, unsteady flow control has been widely considered due to the lower power and momentum requirements compared to the steady flow control method. In unsteady flow control, several parameters affect the separation control on lifting surfaces, including geometric and physical parameters (Bauer, 2015;Hipp et al, 2016) of the main flow (Seifert et al, 2004;Haucke and Nitsche, 2013;Wild, 2015) and the actuation system (Stalnov and Seifert, 2010;Taleghani et al, 2012;Hecklau et al, 2013;Feero et al, 2017;Munday and Taira, 2018;Walker et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Effects of low and high frequency actuation on aerodynamic performance of a supercritical airfoil

Abdolahipour

2023

Front. Mech. Eng.

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The main objective of this study is to investigate the effects of low and high frequency actuation in improving the aerodynamic performance of the supercritical airfoil with the approach of using it in a high-lift or flight control device. For this purpose, a flow control numerical simulation is performed on a supercritical airfoil with NASA SC(2)-0714 cross section using a pulsed jet at the chord-based Reynolds number of 1 × 106. The pulsed jet actuation with different reduced frequencies of 0.2, 1, 1.2, 2.4, 4, 6, and 12 is implemented on the upper side of the airfoil surface upstream of the separation point of the uncontrolled case. The aerodynamic efficiency improvements are investigated by extracting the results of time-averaged and instantaneous aerodynamic forces for all cases. The study compares the flow streamline, Q-criterion contour, and surface pressure distribution to examine how the separated flow configuration over the airfoil responds to different actuation frequencies. The results indicate that pulsed jet actuation effectively postpones the flow separation. A comparison of the time-averaged aerodynamic coefficients at different actuation frequencies revealed that utilizing a low actuation frequency range maximizes lift, while a high frequency range minimizes drag. In addition, the aerodynamic efficiency of the supercritical airfoil improves across all controlled scenarios, with the optimal increase in aerodynamic efficiency of 28.62% achieved at an actuation frequency of F+ = 1.

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Control of Poststall Airfoil Using Leading-Edge Pulsed Jets

Cited by 15 publications

References 25 publications

Effects of Wall-Normal and Angular Momentum Injections in Airfoil Separation Control

Effects of Wall-Normal and Angular Momentum Injections in Airfoil Separation Control

Current state and future trends in boundary layer control on lifting surfaces

Effects of low and high frequency actuation on aerodynamic performance of a supercritical airfoil

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