Transitory Control of Dynamic Stall on a Pitching Airfoil

Woo, George T. K.; Glezer, Ari

doi:10.1007/978-3-642-11735-0_1

Cited by 10 publications

(5 citation statements)

References 27 publications

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“…This kind of separation resembles the separated flow around a stalled aerofoil characterized by an early stage shear layer defined by small fluid structures, and a downstream wake mainly composed by large eddies. Previous works of similar aerodynamic conditions have shown the effectiveness of a flow control device, for both static stalled [10,11] and pitching [12,13] aerofoils. Taking inspiration from the flow control techniques developed in this field, an AFC strategy is investigated and readapted here for ground vehicles.…”

Section: Introductionmentioning

confidence: 99%

Active Aerodynamic Control of a Separated Flow Using Streamwise Synthetic Jets

Minelli

Tokarev

Zhang

et al. 2019

Flow Turbulence Combust

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LES simulations at Re = 1 × 10 5 and wind tunnel experiments at Re = 5 × 10 5 were conducted to investigate the beneficial effect of an active flow control (AFC) technique on the aerodynamic performance of a simplified truck geometry. The paper involves the investigation of a synthetic jet actuator characterized by periodic blowing and suction that defines a zero net mass flux flow control mechanism. The actuation aims to suppress the flow separation occurring at the A-pillar (front rounded corner) of a truck cabin. The work flow is defined as it follows. First, LES at low Reynolds number are conducted for different disposition of the actuation slots. The results show a beneficial effect when the actuation slots are positioned in streamwise direction compared to spanwise (vertical) direction. Second, based on the previous considerations, wind tunnel experiments are conducted to verify and support the numerical findings. Both numerical solutions and experimental data show the same trend and the superiority of the streamwise slots actuation when compared to traditional vertical slot actuation. In particular, this work shows the weakness of a vertical slot actuation, when its location is not optimized. A small change in its positioning greatly worsen the efficacy of the separation control in terms of drag reduction and separation bubble length. The slot location directly affects the length of the separated flow region which its reduction can vary between 40-70% based on the positioning. Conversely, a streamwise actuation, spanning a larger portion of the curvature of a rounded A-pillar, is not affected by this behaviour and contributes up to 80% of the recirculation bubble reduction measured in the unactuated case. The effect of the location change and the orientation of a zero net mass flux jet slot is therefore investigated and discussed in this work.

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Section: Introductionmentioning

confidence: 99%

Active Aerodynamic Control of a Separated Flow Using Streamwise Synthetic Jets

Minelli

Tokarev

Zhang

et al. 2019

Flow Turbulence Combust

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“…St L = 10 can be highly effective in controlling separation from cylinders and aerofoils. Woo & Glezer [28] also show, by reference to a range of experiments on an aerofoil configuration, that an asymmetric duty cycle-a very short ejection stroke, followed by a relatively long ingestion stroke-is also highly conducive to separation control. Both observations are intriguing.…”

Section: Slot Jetsmentioning

confidence: 96%

Simulation of slot and round synthetic jets in the context of boundary-layer separation control

Leschziner

Lardeau

2011

Phil. Trans. R. Soc. A.

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Synthetic jets-also referred to as mass-less jets-offer the potential of effective, on-demand, fluid-based control of separating boundary layers on highly loaded aerodynamic surfaces, without the need for a mass source. However, the control authority that may optimally be derived from such jets, and any generality of the underlying flow physics are obscured by the wide range of geometric and flow parameters that contribute to their performance characteristics. The present article reviews the state-of-the art in the area of computational modelling and simulation of synthetic jets, with emphasis placed on key fluid-mechanics phenomena. The review is divided into two principal parts, one focusing on slot jets and the other on round jets. Within the latter part, ongoing research by the authors on the simulation of synthetic jets discharged into a separated boundary layer is highlighted as an example of the current status in this area.

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“…A few actuation methods that have proven to be successful for producing time-varying lift include 1) variablestrength "steady" jets [3,43], 2) variable-amplitude burst-mode actuation with synthetic jets [44][45][46][47], 3) burst-mode combustion actuators [48][49][50][51], and 4) variable-voltage dielectric barrier discharge plasma actuators [52,53].…”

Section: Identifying Models For the Dynamic Response To Control mentioning

confidence: 99%

Alleviating Unsteady Aerodynamic Loads with Closed-Loop Flow Control

Williams

King

2018

AIAA Journal

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The practical benefits and issues related to controlling unsteady loads in gusting flows with active flow control actuators are discussed. Recent methods used to model the response of flight and road vehicles to unsteady flow disturbances, as well as modeling approaches for the dynamic effects of active flow control, are presented in the framework of a feedforward/feedback control architecture. Limitations of the achievable control performance are discussed. For instance, the lift reversal and the delay time required for the lift increment to reach its maximum value are responsible for limiting the bandwidth that can be achieved with active flow control of separated flows. An estimate of the practical gust bandwidth that can be controlled with aircraft is made.

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Transitory Control of Dynamic Stall on a Pitching Airfoil

Cited by 10 publications

References 27 publications

Active Aerodynamic Control of a Separated Flow Using Streamwise Synthetic Jets

Active Aerodynamic Control of a Separated Flow Using Streamwise Synthetic Jets

Simulation of slot and round synthetic jets in the context of boundary-layer separation control

Alleviating Unsteady Aerodynamic Loads with Closed-Loop Flow Control

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