Tip-Disturbance Effects on Asymmetric Vortex Breakdown Around a Chined Forebody

Ma, Bao-Feng; Xueying, Deng

doi:10.2514/1.31352

Cited by 8 publications

(2 citation statements)

References 21 publications

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“…Wing rock characteristics of aerodynamic bodies are so widely varied that in most cases investigation / analysis of wing rock has been made configuration based, such as for slender delta wings [1][2][3], for low sweep delta wings [4][5], for slender forebodies [6][7][8] and for chined fuselage [9][10] etc. However, one thing is common to all these configurations: when these types of surfaces operate at high angles of attack, the flow field is vortex dominated.…”

Section: Introductionmentioning

confidence: 99%

Suppression of Wing Rock in Slender Delta Wing by Horizontal Strakes

Bakaul

Wang

Guangxing

2015

AIAA Atmospheric Flight Mechanics Conference

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Experimental investigations of this paper show that delta and reverse delta shaped small horizontal strakes (fineness ratio of 3%-5%) are capable of suppressing wing rock of slender delta wing above 35° angle of attack. Parametric study reveals that 45° sweep back and sweep forward angles are the most favourable combinations while most advantageous stream-wise location of strake is the beginning of the delta wing. The suppression capability is also evident during pitching-up, but no significant deterioration of lift to drag ratio is observed. The suppression is achieved by changes in the vortical flow field brought in by the strakes. During a roll, the strake (a) alters the 'away' normal and 'outward' spatial location of up-going semi-span's vortex to 'closer' normal and 'inward' spatial location, and (b) reduces the difference in normal distances of vortices of two semi-spans, both of which are the characteristics of no wing rock regime such as 15° angle of attack. Thus, the strake changes the 'asymmetric' flow to 'nearly symmetric'. Such change in vortical flow field is caused by the interaction of two vortices emanating from the strake with the vortex pair originating from delta wing. Nomenclature= angle of attack, degree = maximum amplitude of oscillation, degree = span of delta wing, m = drag co-efficient = lift co-efficient = root chord length of delta wing, m = root chord of strake, m = roll angle, degree = mean roll angle, degree = fineness ratio = / / = lift to drag ratio = local semi-span, m ∞ = freestream velocity, m/sec = pitch rate, degree/sec = non-dimensional pitch rate = 2 ∞

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Section: Introductionmentioning

confidence: 99%

Suppression of Wing Rock in Slender Delta Wing by Horizontal Strakes

Bakaul

Wang

Guangxing

2015

AIAA Atmospheric Flight Mechanics Conference

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“…Unfortunately, there has not been any unified theory explaining the phenomenon in general, rather the reasons behind wing rock have been explained on configuration dependent basis. Configurations like slender delta wings [1][2], low sweep delta wings [3][4], slender forebody [5][6], chined fuselage [7][8] etc have been studied extensively. The reasons highlighted by these studies include factors like nonlinearities of rolling and yawing moment coefficients with roll and/or yaw angle, static hysteresis with roll and/or yaw angle, variation in roll damping with sideslip angle etc.…”

Section: Introductionmentioning

confidence: 99%

Effect of Nose Tip on Wing Rock of Slender Delta Wing

Bakaul

Wang

et al. 2012

AMM

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The root cause of wing rock is investigated by examining two slender delta wings (700 and 850 sweep back angle) in wind tunnel using force measurement, pressure measurement and PIV techniques. The results show presence of asymmetric flow at 200 angle of attack and initiation of wing rock at the same point for 850 model while there is neither asymmetric flow nor wing rock for 700 model suggesting close relation of flow asymmetry with wing rock. Investigation with three apparently identical nose sections reveals that the asymmetry comes from the area very close to the wing tip. This asymmetric flow causes the vortices to interact in a complex way resulting in wing rock when the vortices are in close proximity (such as for 850 model), which is not the case when the vortices are ‘comparatively away’ (such as 700 model) from each other.

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