Dynamic Behavior and Gust Simulation in an Unsteady Flow Wind Tunnel

Rennie, R. Mark; Catron, Brian; Feroz, Muhammad Zubair; Williams, David R.; He, Xiaowei

doi:10.2514/1.j057186

Cited by 20 publications

(3 citation statements)

References 17 publications

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“…Wei et al (2019) generated gusts with peak-to-peak deflection angles of only 4.5°, but used an active turbulence grid that can produce sinusoidal variations in either one or two directions. Another unique setup is that of a cross-flow passage on an unsteady flow wind tunnel so that flow disturbances can be produced in two directions: ∼10°of flow deflection in the transverse direction and ∼10% variation in the freestream direction (He & Williams 2020, He et al 2021, Rennie et al 2019.…”

Section: Experimental Considerationsmentioning

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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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%

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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“…This gust device based on pitching blades has also been widely used in other recent studies (Williams & King 2018; Mark Rennie et al. 2019; Li, Li & Shi 2021). The spacing between the two blades is 380 mm.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…Both blades are constructed from a combination of resin material and carbon fibre plates, providing them with ample rigidity. This gust device based on pitching blades has also been widely used in other recent studies (Williams & King 2018;Mark Rennie et al 2019;Li, Li & Shi 2021). The spacing between the two blades is 380 mm.…”

Section: Experimental Set-upmentioning

confidence: 99%

Airfoil response to periodic vertical and longitudinal gusts

Wang,

Feng,

Cao

et al. 2024

J. Fluid Mech.

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Gust response has consistently been a concern in engineering. Critical theories have been proposed in the past to predict the unsteady lift response of an airfoil experiencing vertical gusts by Atassi, and longitudinal gusts by Greenberg. However, their applicability for an airfoil with non-zero angles of attack still needs clarification. Thus, force measurements are conducted to examine these theories’ validity and quasi-steady corrections are applied to compensate potential disparities between the idealised and real flow conditions. Velocity measurements are performed to scrutinise the effect of gusts on the flow around the airfoil, and subsequently to reveal the underlying mechanism governing the airfoil's response to gust-induced perturbations. In the study, two pitching vanes are arranged upstream to generate periodic vertical and longitudinal gusts, whereas a downstream airfoil with angles of attack of 0–12° is subjected to two gust types. It is found that Greenberg's theory demonstrates superior predictive capability in pre-stall regimes, with the potential for its effectiveness to be expanded to post-stall regimes through theoretical refinements. In contrast, Atassi's theory exhibits significant deviations from experimental outcomes across the measured angles of attack. Nevertheless, a modified version of the theory aligns better with experimental results at small angles of attack, whereas substantial discrepancies persist as the angle of attack increases. In the pre-stall regime, the aerodynamic response of the airfoil to vertical gusts displays a linear correlation with the flow angle near the leading edge. In the post-stall regime, the vertical gust induces dynamic stall of the airfoil. The flow angle has an essential effect on the lift coefficient but it alone is inadequate to dictate the trend of the lift coefficient. The vorticity statistics show that negative vortex circulation strongly correlates with the lift coefficient. Thus, further correction of the theory or a new vortex model can be expected to predict the lift variation.

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