Controlling Flow Separation on a Thick Airfoil Using Backward Traveling Waves

Akbarzadeh, Amir; Borazjani, Iman

doi:10.2514/1.j059428

Cited by 26 publications

(7 citation statements)

References 59 publications

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“…V is associated with amplitude of the wave, not wave speed, and must satisfy a certain threshold in order for actuation to have an effect. The highest lift to drag ratio found by Akbarzadeh and Borazjani (2020) was with traveling waves having non-dimensional velocity (U = V/u ∞ ) of 0.1 -V is 10 times slower than the free stream velocity (u ∞ ). TSR and U were looked at with a varying design parameter for actuator arrangement, δ p .…”

Section: With Respect To Actuation Characteristicsmentioning

confidence: 94%

Flow control and separation delay in morphing wing aircraft using traveling wave actuation

Olivett

Corrao

Karami

2021

Smart Mater. Struct.

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This study examines the biomimicry of wave propagation, a mode of locomotion in aquatic life for the use-case of morphing aircraft surfaces for boundary layer control. Such motion is theorized to inject momentum into the flow on the upper surface of airfoils, and as a consequence, creates a forcible pressure gradient thereby increasing lift. It is proposed that this method can be used to control flow separation and reduce the likelihood of stall at high angles of attack. The motivation for such a mechanism is especially relevant for aircraft requiring abrupt maneuvers, and especially at high angles of attack as a safety measure against stalling. The actuation mechanism consists of lightweight piezoelectric ceramic transducers placed beneath the upper surface of an airfoil. An open-loop system controls surface morphing. A two-dimensional Fourier Transform technique is used to estimate traveling to standing wave ratio, which is verified analytically using Euler Bernoulli beam theory, and experimentally using a prototype wing. Propagating wave control is tuned and verified using a series of scanning laser vibrometry tests. A custom two-dimensional NACA 0018 airfoil tests the concept in a low-speed wind tunnel with an approximate Reynolds Number of 50 000. Both traveling waves and the changes in lift and drag will be experimentally characterized.

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Section: With Respect To Actuation Characteristicsmentioning

confidence: 94%

Flow control and separation delay in morphing wing aircraft using traveling wave actuation

Olivett

Corrao

Karami

2021

Smart Mater. Struct.

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“…Given the discussion on the generation and evolution of the coherent vortices, and our quantitative/qualitative study on the emergence of strong non-Gaussian statistical behavior for velocity and vorticity fluctuations, one can argue that such statistics are closely tied to and in other words, the direct result of generation and growth of coherent vortical structures due to the effect of the rotational symmetry-breaking factors. In prior studies, such connection was investigated and partially addressed in the contexts of planar mixing and free shear layers [90][91][92] , subgrid-scale (SGS) motions and their nonlocal modeling for homogeneous and wall-bounded turbulent flows 93,94 , boundary layer flows 95,96 , and turbulent flows interacting with wavy-like moving/actuated surfaces (with application to reduction and control of flow separation) 97,98 .…”

Section: Memory Effects In Vorticity Dynamics and Anomalous Time-scal...mentioning

confidence: 99%

Anomalous Features in Internal Cylinder Flow Instabilities subject to Uncertain Rotational Effects

Akhavan-Safaei,

Seyedi,

Zayernouri

2020

Preprint

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“…Flow separation that occurs on an aircraft wing negatively affects aerodynamic performance. Therefore, many studies on the control of flow separation have been conducted [1][2][3][4][5]. Flow control technologies are classified into passive flow control (PFC) [1], which attaches various structures to the surface, and active flow control (AFC) [2], which uses actuators such as plasma actuators [3], backward traveling waves [4], and periodic surface morphing [5].…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, many studies on the control of flow separation have been conducted [1][2][3][4][5]. Flow control technologies are classified into passive flow control (PFC) [1], which attaches various structures to the surface, and active flow control (AFC) [2], which uses actuators such as plasma actuators [3], backward traveling waves [4], and periodic surface morphing [5]. AFC has an advantage of removing the drag-increase problem, which is a disadvantage of PFC, and enables effective separation control [6].…”

Section: Introductionmentioning

confidence: 99%

Effects of Bending of Fluidic Oscillators on Aerodynamic Performance of an Airfoil with a Flap

Kim¹,

Kim²

2021

Processes

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The present work investigated the effects of bending the outlet nozzles of fluidic oscillators installed on the NACA0015 airfoil with a flap on the flow control performance and, thus, the aerodynamic performance of the airfoil. The effects of bending on fluidic oscillators have not been reported so far in previous works. The aerodynamic analysis was performed numerically using unsteady Reynolds-averaged Navier-Stokes equations. Three different cases were considered: Case 1 changes only the bending angle with a fixed pitch angle, Case 2 changes only the pitch angle without bending, and Case 3 changes both the bending and pitch angles. Although the bending of the oscillators was introduced inevitably due to a geometrical limitation in the installation, the results indicated that the bending rather improved the lift coefficient and lift-to-drag ratio of the airfoil by improving the characteristics of the fluidic oscillators, such as the jetting angle and peak velocity ratio.

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Controlling Flow Separation on a Thick Airfoil Using Backward Traveling Waves

Cited by 26 publications

References 59 publications

Flow control and separation delay in morphing wing aircraft using traveling wave actuation

Flow control and separation delay in morphing wing aircraft using traveling wave actuation

Anomalous Features in Internal Cylinder Flow Instabilities subject to Uncertain Rotational Effects

Effects of Bending of Fluidic Oscillators on Aerodynamic Performance of an Airfoil with a Flap

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