Stability of Symmetric and Asymmetric Vortices Pairs over Slender Conical Wing-Body Combinations

Jinsheng Cai; Shijun Luo; Feng Liu

doi:10.2514/1.19677

ASSYMETRY AND NONUNIQUENESS OF THE SOLUTION OF THE PROBLEM OF SEPARATED FLOW OVER A SLENDER CONICAL WING-BODY COMBINATION

TsAGI Science Journal ◽

10.1615/tsagiscij.v40.i6.40 ◽

2009 ◽

Vol 40 (6) ◽

pp. 669-682

Author(s):

A. V. Voevodin

Keyword(s):

Separated Flow ◽

Conical Wing

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Strakes Effects on Asymmetric Flow Over a Blunt-Nosed Slender Body at a High Angle of Attack

Journal of Fluids Engineering ◽

10.1115/1.4041815 ◽

2018 ◽

Vol 141 (6) ◽

Author(s):

Qihang Yuan ◽

Yankui Wang ◽

Zhongyang Qi

Keyword(s):

Angle Of Attack ◽

Slender Body ◽

Axial Position ◽

High Angle ◽

Asymmetric Flow ◽

High Angle Of Attack ◽

Side Force ◽

Asymmetric Vortices ◽

High Angles Of Attack ◽

Blunt Nose

In general speaking, the missiles execute flight at high angles of attack in order to enhance their maneuverability. However, the inevitable side-force, which is caused by the asymmetric flow over these kinds of traditional slender body configurations with blunt nose at a high attack angle, induces the yawing or rolling deviation and the missiles will lose their predicted trajectory consequently. This study examines and diminishes the side-force induced by the inevitable asymmetric flow around this traditional slender body configuration with blunt nose at a high angle of attack (AoA = 50 deg). On one hand, the flow over a fixed blunt-nosed slender body model with strakes mounted at an axial position of x/D = 1.6–2.7 is investigated experimentally at α = 50 deg (D is the diameter of the model). On the other hand, the wingspan of the strakes is varied to investigate its effect on the leeward flow over the model. The Reynolds number is set at ReD = 1.54 × 105 based on D and incoming upstream velocity. The results verify that the formation of asymmetric vortices is hindered by the existence of strakes, and the strake-induced vortices develop symmetrically and contribute to the reduction in side-force of the model. In addition, the increase in strake wingspan reduces asymmetric characteristics of the vortex around the model and causes a significant decrease in side-force in each section measured. The strake with the 0.1D wingspan can reduce the sectional side-force to 25% of that in the condition without strakes.

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Asymmetric Vortices around a Body at High Angle of Attack Supersonic Flow

Journal of the Korean Physical Society ◽

10.3938/jkps.55.2159 ◽

2009 ◽

Vol 55 (5(2)) ◽

pp. 2159-2165 ◽

Cited By ~ 3

Author(s):

Sang Ho Kim ◽

Wansub Kim

Keyword(s):

Supersonic Flow ◽

Angle Of Attack ◽

High Angle ◽

High Angle Of Attack ◽

Asymmetric Vortices

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Spatio-Temporal Development of Supercavitation Over an Impulsively Launched Projectile

Volume 2: Fora ◽

10.1115/fedsm2006-98115 ◽

2006 ◽

Author(s):

C. J. Weiland ◽

P. P. Vlachos

Keyword(s):

High Speed ◽

Temporal Development ◽

Two Phase ◽

Time Resolved ◽

Gas Gun ◽

Supercavitating Flow ◽

Image Velocimetry ◽

Spatio Temporal ◽

Asymmetric Vortices ◽

First Time

Supercavitation inception and formation was studied over blunt projectiles. The projectiles were fired using a gas gun method. In this method, projectiles are launched under the action of expanding detonation gases. Both qualitative and quantitative optical flow diagnostics using high speed digital imaging were used to analyze the spatio-temporal development of the supercavitating flow. For the first time, quantification of the supercavitation was achieved using Time Resolved Digital Particle Image Velocimetry (TRDPIV) detailing the two phase flow field surrounding the translating projectiles and the gas vapor bubble. Experimental results indicate that the supercavity forms at the aft end of the projectile and travels forward along the direction of projectile travel. The impulsive start of the projectile generates two asymmetric vortices which are shed from the blunt nose of the projectile. The vortices interact with the moving cavity and subsequently deform. This interaction is believed to directly contribute to the instabilities in the flight path.

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Effect of nose perturbation on asymmetric vortices over a blunt-nose body at high angle of attack

Journal of Physics Conference Series ◽

10.1088/1742-6596/822/1/012053 ◽

2017 ◽

Vol 822 ◽

pp. 012053

Author(s):

Y.X. Sha ◽

Y.K. Wang ◽

Z.Y. Qi

Keyword(s):

Angle Of Attack ◽

High Angle ◽

High Angle Of Attack ◽

Asymmetric Vortices ◽

Blunt Nose

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Vortex merger in rotating stratified flows

Journal of Fluid Mechanics ◽

10.1017/s0022112001007364 ◽

2002 ◽

Vol 455 ◽

pp. 83-101 ◽

Cited By ~ 26

Author(s):

DAVID G. DRITSCHEL

Keyword(s):

Aspect Ratio ◽

Initial Conditions ◽

Random Noise ◽

Three Dimensional ◽

Separation Distance ◽

Two Dimensional ◽

Initial Separation ◽

Weak Exchange ◽

First Results ◽

Asymmetric Vortices

This paper describes the interaction of symmetric vortices in a three-dimensional quasi-geostrophic fluid. The initial vortices are taken to be uniform-potential-vorticity ellipsoids, of height 2h and width 2R, and with centres at (±d/2; 0, 0), embedded within a background flow having constant background rotational and buoyancy frequencies, f/2 and N respectively. This problem was previously studied by von Hardenburg et al. (2000), who determined the dimensionless critical merger distance d/R as a function of the height-to-width aspect ratio h/R (scaled by f/N). Their study, however, was limited to small to moderate values of h/R, as it was anticipated that merger at large h/R would reduce to that for two columnar two-dimensional vortices, i.e. d/R ≈ 3.31. Here, it is shown that no such two-dimensional limit exists; merger is found to occur at any aspect ratio, with d ∼ h for h/R [Gt ] 1.New results are also found for small to moderate values of h/R. In particular, our numerical simulations reveal that asymmetric merger is predominant, despite the initial conditions, if one includes a small amount of random noise. For small to moderate h/R, decreasing the initial separation distance d first results in a weak exchange of material, with one vortex growing at the expense of the other. As d decreases further, this exchange increases and leads to two dominant but strongly asymmetric vortices. Finally, for yet smaller d, rapid merger into a single dominant vortex occurs – in effect the initial vortices exchange nearly all of their material with one another in a nearly symmetrical fashion.

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