Zonal techniques for flowfield simulation about aircraft

Walters, Robert W.; Reu, Taekyu; McGrory, William D.; Thomas, James L.

doi:10.1016/0045-7949(88)90213-1

Cited by 3 publications

(2 citation statements)

References 8 publications

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“…The two-dimensional grid in the cross plane was generated using a grid generator provided by McGrory 18 that was originally developed to construct the grid for the calculation of the SR-71 flowfield. 19 The boundaries upstream of the nose, and radially away, were initially selected to be consistent with the F/A-18 calculations. 5 The forward boundary extends upstream of the nose by 0.62/, and radial outer boundary extends 0.98/ from the model centerline (8.4 equivalent body radii).…”

Section: Computational Gridmentioning

confidence: 99%

Computational study of the F-5A forebody emphasizing directional stability

Mason

Ravi

1994

Journal of Aircraft

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Computational fluid dynamics (CFD) has been used to study the F-5A forebody flowfield at low-speed high angle-of-attack conditions combined with sideslip. The classic wind-tunnel experiment demonstrating the dominant contribution of the F-5A forebody to directional stability at high angle of attack has been simulated computationally over an angle-of-attack range from 10 to 45 deg. The key wind-tunnel trend for C nft was obtained computationally using the CFL3D code to solve the Reynolds' equations employing the Baldwin-Lomax turbulence model with the Degani-Schiff modification to account for massive crossflow separation. The computations provide detailed and fascinating insights into the physics of flowfield. The results of the investigation show that CFD has reached a level of development where computational methods can be used for high angle-of-attack aerodynamic design. Nomenclature b' = wingspan based on F-5A wind-tunnel model, 52.68 in. C L = lift coefficient, \ift/q^S ref C m = pitching-moment coefficient, pitching moment/g^ S^Z/ C n = yawing-moment coefficient, yawing moment/q^S^b' C, l/3 = directional stability derivative, dC n /d/3 C p = pressure coefficient, (p -p^)/qĈ v = side-force coefficient, side force/'q^S Tef c = mean aerodynamic chord, 16.08 in. c v = sectional side force, section side force/'qF S = fuselage station / = forebody model length, 31.025 in. M x = freestream Mach number, 0.2 p = pressure p x = freestream pressure q^, = freestream dynamic pressure Re, = Reynolds number based on model length, 1.25 x 10 6 5 ref = reference area, 754.56 in. 2 u* = wall friction velocity, Vr^/p F sep = crossflow velocity magnitude at separation point (chine edge) jc, y, z = coordinate system: x positive aft on model axis, y positive to right, and z positive up y + = inner law variable, yu*lv a = angle of attack, deg j8 = angle of sideslip, deg AC P = difference between leeward and windward C p across the vertical plane of symmetry 0 = azimuthal angle, measured clockwise from windward plane at any cross section p = density T W = shear stress at the wall Presented as Paper 91-3289 at the AIAA 9th

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Section: Computational Gridmentioning

confidence: 99%

Computational study of the F-5A forebody emphasizing directional stability

Mason

Ravi

1994

Journal of Aircraft

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“…He proposed a conservative scheme for patched grids with Euler equations. Walters et al [12] and Thomas et al [13] extended this to three-dimensional viscous flow with cell-centered schemes. Ferm and L otstedt [14] have investigated the stability of discretizations for second order accurate schemes at patch interfaces.…”

Section: Introductionmentioning

confidence: 99%

A Combined Implementation of Overset Grid and Patched Grid Methodologies

Puttam

2016

Fluid Mechanics and Fluid Power – Contemporary Research

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The paper discusses the combined implementation of overset grid and patched grid methodologies and it's testing for transonic and supersonic flows. The motivation is to make the grid generation process easier and less time consuming as well as having optimum resolution as per the requirement of local flow gradients, with no effect on the accuracy of simulation. In the near-body region body fitted curvilinear structured grid and in the off-body region Cartesian grid layers with gradual coarser resolution away from the body were used. Curvilinear and Cartesian blocks were coupled with overset grid technique, where as different Cartesian layers were coupled through grid patching. In the overset grid module, barycentric coordinates were used to search the donor cells of each fringe cell. Area weighted averaging was utilised for fringe cell conservative variable interpolation from their corresponding donor cells and it preserved the conservation at shocks without generating spurious oscillations. The area fractions required for area weighted averaging were found by using polygon clipping algorithm in efficient manner. Steady state inviscid & viscous flows and unsteady state moving shock simulations were carried out to test with patched grid and overset grid combination and shocks passed through these block boundaries without getting distorted.

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