Effect of a Rotating and Swept Wingtip on Streamwise Gust Alleviation

Chowdhury, Juhi; Ringuette, Matthew

doi:10.2514/1.j059690

Cited by 10 publications

(4 citation statements)

References 30 publications

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“…Strong streamwise disturbances can be achieved in water by towing a model with an unsteady motion either in a quiescent fluid (Chowdhury & Ringuette 2021, Marzanek & Rival 2019, Mulleners et al 2017 or in the presence of a freestream (Granlund et al 2016). In many ways, towed-model streamwise gust encounters are easier to perform than true gust encounters.…”

Section: Experimental Considerationsmentioning

confidence: 99%

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Physics and Modeling of Large Flow Disturbances: Discrete Gust Encounters for Modern Air Vehicles

Jones

Çeti̇ner

Smith

2022

Annu. Rev. Fluid Mech.

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Gusts of moderate and large magnitude induce flow separation and other complexities when they interact with the lifting surfaces of air vehicles. The presence of these nonlinear gusts are becoming ubiquitous in twenty-first-century air vehicles, where the classic potential flow–based methodologies applied in the past may no longer be valid. In this review, we define the parameter space for the presence of large-amplitude gusts and describe where and when these gusts may primarily be found. Recent research using modern experimental and computational techniques to define the limits of classical unsteady and indicial aerodynamic theories is summarized, with a focus on discrete transverse, streamwise (longitudinal), and vortex gust encounters. We propose areas where future research is needed to transition these studies of large-amplitude gust physics to real-time prediction and mitigation during flight. Expected final online publication date for the Annual Review of Fluid Mechanics, Volume 54 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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Section: Experimental Considerationsmentioning

confidence: 99%

“…It is possible to achieve very good gust mitigation results for flow disturbances in the streamwise direction (Chowdhury & Ringuette 2021). These types of gusts may be the easiest to control because the effective angle of attack of the wing does not change.…”

Section: Mitigating Gust Responsementioning

confidence: 99%

Physics and Modeling of Large Flow Disturbances: Discrete Gust Encounters for Modern Air Vehicles

Jones

Çeti̇ner

Smith

2022

Annu. Rev. Fluid Mech.

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“…For example the active control system employed in the Lockheed L-1011-500 aircraft provided both manoeuvre and gust load alleviation by actively adjusting the horizontal stabiliser and ailerons according to flight data gathered from the sensors installed on the airframe,and a 1.25% reduction in structural weight was achieved [11]. Many wingtip devices have been developed to mitigate gust loads, operating either actively or passively to reduce the lifting force generated on the outboard section of the wing [12][13][14]. Compliant based approaches have also been proposed for wingtip designs, such as chiral structures or corrugated panels which allows wingtip morphing throughout the flight envelope to maximise the overall efficiency [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Sizing of High Aspect Ratio Wings with Folding Wing Tips

Healy

Rezgui

et al. 2022

AIAA SCITECH 2022 Forum

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“…We want to investigate the effect of controlled shape change of a flat plate on its surrounding flow field and the unsteady forces during an accelerating manoeuvre. Dynamic planform variation has been recently shown to be beneficial in highly unsteady flows (Huera-Huarte & Gharib 2017; Chowdhury & Ringuette 2021). In our present work, we actively control the span deformation of an accelerating flat plate held at an angle of attack of .…”

Section: Introductionmentioning

confidence: 99%

The unsteady force response of an accelerating flat plate with controlled spanwise bending

Joshi

Bhattacharya

2022

J. Fluid Mech.

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The unsteady force response of an accelerating flat plate, subjected to controlled spanwise bending, is investigated experimentally. The flat plate was held normal to the flow (at an angle of attack of $90^{\circ }$ ), and it was dynamically bent along the spanwise direction with the help of internal actuation. Two bending directions were tested. In one case, part of the plate (denoted by flexion ratio) was bent into the incoming flow (the bend-down configuration). In another case, the plate was bent away from the flow (the bend-up configuration). We used two different aspect ratio ( $AR$ ) plates, namely $AR = 2$ and 3. Three acceleration numbers, namely $A_c = 0.57$ , 1.6 and 3.2 (corresponding to dimensional acceleration of 0.036, 0.1 and 0.2 m s $^{-2}$ , respectively) were tested with a fixed terminal Reynolds number (Re) of 18 000. For each acceleration number, three bending durations, namely 1.2, 2.4 and 3.6 s were implemented. The results indicate that the highest impulse was imparted by the highest bending rate (duration 1.2 s) during all three accelerations tested. We show that controlled spanwise bending can significantly change the unsteady force response by manipulating the inertial forces during a start-up manoeuvre. The unsteady forces depend on the vector sum of the forward acceleration and the bending acceleration of the plate. The unsteady drag was augmented when the plate was bent towards the incoming flow. The initial force peaks were significantly reduced when the bending direction was reversed. The development of the edge vortices from the flat plate was measured with the help of particle image velocimetry (PIV) at the 70 % and the 90 % span locations. The PIV measurements were also carried out at the midchord plane closer to the tip region to capture the growth of the tip vortex. The vorticity field calculated from these PIV measurements revealed that controlled bending contributed to a variation in the circulation growth of the edge vortices. During the bend-down case, the circulation growth was faster and the tip vortices stayed closer to the plate. This resulted in increased interaction with the edge vortex at the 90 % span. This interaction was more severe for $AR = 2$ . During the bend-up case, the growth of the edge vortex was delayed, but the vortex grew for a longer time compared with the bend-down case. Finally, a mathematical model is presented which correctly captured the trend of the force histories measured experimentally during both the bend-up and bend-down cases.

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Effect of a Rotating and Swept Wingtip on Streamwise Gust Alleviation

Cited by 10 publications

References 30 publications

Physics and Modeling of Large Flow Disturbances: Discrete Gust Encounters for Modern Air Vehicles

Physics and Modeling of Large Flow Disturbances: Discrete Gust Encounters for Modern Air Vehicles

Sizing of High Aspect Ratio Wings with Folding Wing Tips

The unsteady force response of an accelerating flat plate with controlled spanwise bending

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