Effects of nonplanar outboard wing forms on a wing

Naik, D. A.; Ostowari, C.

doi:10.2514/3.45906

Cited by 15 publications

(6 citation statements)

References 5 publications

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“…Also shown in figure 4e are the C Di values estimated from C Di = C 2 L /(K + 1/πeAR) (denoted by the dashed line). K is the pressure-drag magnification factor and has a typical value of 0.007 (Naik & Ostowari 1990), and e = 0.9 is the Oswald wing-span efficiency factor. The results show that Prandtl's classical lifting-line theory overpredicts the C Di (an order of magnitude larger) for the present near-field low-Reynolds-number experiment with an AR < 4.…”

Section: Variation Of Vortex Flow With X/cmentioning

confidence: 99%

Investigation of the near-field tip vortex behind an oscillating wing

Birch

Lee

2005

J. Fluid Mech.

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The near-field tip-vortex flow structure behind an oscillating NACA 0015 wing was investigated at ${\hbox {{\it Re}}}\,{=}\,1.86 \times 10^{5}$. For attached-flow and light-stall oscillations, a small hysteretic property existed between the pitch-up and pitch-down motion, and many of the vortex flow features were found to be qualitatively similar to those of a static wing. For deep-stall oscillations, the wing oscillations imposed a strong discrepancy in contour shapes and magnitudes between the pitch-up and pitch-down phases of the oscillation cycle. The vortex was less organized during pitch-down (as a result of leading-edge-vortex-induced massive flow separation) than during pitch-up. The tangential velocity, circulation and lift-induced drag increased progressively with the airfoil incidence, and had higher magnitudes during pitch-up than during pitch-down, while varying slightly with the downstream distance. The vortex size, however, was larger during pitch-down than during pitch-up. The axial flow was always wake-like during the deep-stall oscillation cycle. The normalized circulation within the inner region of the tip vortex also exhibited a self-similar structure, similar to that of a static wing, and was insensitive to the reduced frequency.

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Section: Variation Of Vortex Flow With X/cmentioning

confidence: 99%

Investigation of the near-field tip vortex behind an oscillating wing

Birch

Lee

2005

J. Fluid Mech.

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“…A number of experiments (for example, Corsiglia et al 1973;Francis and Kennedy 1979;Green and Acosta 1991;McAlister and Takahashi 1991;Shekarriz et al 1993;Chow et al 1997;Ramaprian and Zheng 1997;Birch and Lee 2004;Lee and Pereira 2010) have been conducted to characterize the dynamics of the initial rollup of a tip vortex around the wing tip and its subsequent development in the near field (normally within two or three chord lengths downstream of the wing trailing edge) of a wing. Meanwhile, various passive control devices such as winglets, spoilers, stub/subwing, and porous tips and leading edges (Spillman 1978;Tangler 1978;Muller 1990;Naik and Ostowari 1990;Lee 1994;Liu et al 2001;Lee and Lee 2006) have also been attempted to modify the strength and structure, including the trajectory, of a tip vortex.…”

Section: List Of Symbols Armentioning

confidence: 99%

Wingtip vortex control via the use of a reverse half-delta wing

Lee

2012

Exp Fluids

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The effect of a 65°sweep reverse half-delta wing (RHDW), mounted at the squared tip of a rectangular NACA 0012 wing, on the tip vortex was investigated experimentally at Re = 2.45 9 10 5 . The RHDW was found to produce a weaker tip vortex with a lower vorticity level and, more importantly, a reduced lift-induced drag compared to the baseline wing. In addition to the lift increment, the RHDW also produced a large separated wake flow and subsequently an increased profile drag. The reduction in lift-induced drag, however, outperformed the increase in profile drag and resulted in a virtually unchanged total drag in comparison with the baseline wing. Physical mechanisms responsible for the RHDW-induced appealing aerodynamics and vortex flow modifications were discussed. List of symbolsSpan efficiency factor r Radial distance r c Vortex core radius ReChord Reynolds number = u ? c/t s Semi-span s RHDW RHDW semi-span S BW Baseline-wing area S RHDW RHDW surface area S total Total wing area = S BW ? S RHDW u c

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“…Sheared wing tips present a breakdown of the single tip vortex in three vortexes: a small tip vortex, a separation-induced leading-edge vortex and a secondary vortex that sheds from the junction of the main wing and the sheared wing tip. Each of them presents less intensity in comparison with a single vortex presented at basic wing, reducing total wing vortex drag (Vijgen et al , 1989; Van Dam, 1989; Naik and Ostowari, 1990; Spivey and Morehouse, 1970; Siddiqui et al , 2017). Moreover, these wing tips demonstrated negligible wing root bending moment increment.…”

Section: Introductionmentioning

confidence: 99%

“…Sheared wing tips have a simple geometric planform and can be adopted in current airplane design, and therefore can offer a good compromise between performance and cost. Past researches (Van Dam, 1989; Naik and Ostowari, 1990) demonstrated the benefits of the sheared wing tips but very few have been focused on the parametric evaluation of the effects of combination in wing tip leading edge swept angle and the wing tip tapered ratio, keeping the wing aspect ratio (AR) constant and looking for the best compromise between these parameters for a typical low-to-moderate-aspect-ratio wing of a general aviation aircraft. To the authors’ best knowledge, there are no (or very scarce) studies about this main topic.…”

Section: Introductionmentioning

confidence: 99%

An experimental parametric study on planar sheared wings tip devices for low-to-moderate aspect ratio wings

Santos¹,

Gomes²,

Coimbra³

2021

AEAT

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Purpose The purpose of this study is to investigate the aerodynamic characteristics of a low-to-moderate-aspect-ratio, tapered, untwisted, unswept wing, equipped of sheared wing tips. Design/methodology/approach In this work, wind tunnel tests were made to study the influence in aerodynamic characteristics over a typical low-to-moderate-aspect-ratio wing of a general aviation aircraft, equipped with sheared – swept and tapered planar – wing tips. An experimental parametric study of different wing tips was tested. Variations in its leading and trailing edge sweep angle as well as variations in wing tip taper ratio were considered. Sheared wing tips modify the flow pattern in the outboard region of the wing producing a vortex flow at the wing tip leading edge, enhancing lift at high angles of attack. Findings The induced drag is responsible for nearly 50% of aircraft total drag and can be reduced through modifications to the wing tip. Some wing tip models present complex geometries and many of them present benefits in particular flight conditions. Results have demonstrated that sweeping the wing tip leading edge between 60 and 65 degrees offers an increment in wing aerodynamic efficiency, especially at high lift conditions. However, results have demonstrated that moderate wing tip taper ratio (0.50) has better aerodynamic benefits than highly tapered wing tips (from 0.25 to 0.15), even with little less wing tip leading edge sweep angle (from 57 to 62 degrees). The moderate wing tip taper ratio (0.50) offers more wing area and wing span than the wings with highly tapered wing tips, for the same aspect ratio wing. Originality/value Although many studies have been reported on the aerodynamics of wing tips, most of them presented complex non-planar geometries and were developed for cruise flight in high subsonic regime (low lift coefficient). In this work, an exploration and parametric study through wind tunnel tests were made, to evaluate the influence in aerodynamic characteristics of a low-to-moderate-aspect-ratio, tapered, untwisted, unswept wing, equipped of sheared wing tips (wing tips highly swept and tapered).

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Effects of nonplanar outboard wing forms on a wing

Cited by 15 publications

References 5 publications

Investigation of the near-field tip vortex behind an oscillating wing

Investigation of the near-field tip vortex behind an oscillating wing

Wingtip vortex control via the use of a reverse half-delta wing

An experimental parametric study on planar sheared wings tip devices for low-to-moderate aspect ratio wings

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