scholarly journals CFD Analysis of the Sideslip Angle Effect around a BWB Type Configuration

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Arim Ko ◽  
Kyoungsik Chang ◽  
Dong-Jin Sheen ◽  
Young-Hee Jo ◽  
Ho Joon Shim
Keyword(s):  
Skin Friction ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Sideslip Angle ◽  
Rolling Moment ◽  
Freestream Velocity ◽  
Highly Nonlinear ◽  
Grid Points ◽  
Lift And Drag

In this study, we conducted numerical simulations for a nonslender BWB type planform with a rounded leading edge and span of 2.0 m to analyze the effect of the sideslip angle on the planform at a freestream velocity of 60 m/s. The Reynolds number based on the mean chord length was 2.9×106, and we considered the angle of attack ranging from -4° to 16° and sideslip angles up to 20°. We used an unstructured mesh with a prism layer for the boundary layer with 1.11×107 grid points, and the k−ω SST turbulence model. We analyzed force and moment coefficients with respect to variation of angle of attack and sideslip angles. Side force and rolling/yawing moment coefficients had highly nonlinear relationships with the sideslip angle while lift and drag coefficients were not significantly affected. We interpreted the mechanism of these aerodynamic characteristics based on pressure and skin friction contours. Suction pressure near the leading edge had a marked effect on the pitching and rolling moment. We identified five flow types on the blunt leading edge swept wing by skin friction lines and off-body streamlines at a high angle of attack and sideslip angles.

Numerical study of geometric morphing wings of the 1303 UCAV

2021 ◽  
pp. 1-17
Author(s):  
B. Nugroho ◽  
J. Brett ◽  
B.T. Bleckly ◽  
R.C. Chin
Keyword(s):  
Flight Control ◽  
Numerical Study ◽  
Aerodynamic Characteristics ◽  
Morphing Wing ◽  
Rolling Moment ◽  
Wide Range ◽  
Morphing Wings ◽  
Wing Geometry ◽  
Lift And Drag ◽  
Wing Morphing

ABSTRACT Unmanned Combat Aerial Vehicles (UCAVs) are believed by many to be the future of aerial strike/reconnaissance capability. This belief led to the design of the UCAV 1303 by Boeing Phantom Works and the US Airforce Lab in the late 1990s. Because UCAV 1303 is expected to take on a wide range of mission roles that are risky for human pilots, it needs to be highly adaptable. Geometric morphing can provide such adaptability and allow the UCAV 1303 to optimise its physical feature mid-flight to increase the lift-to-drag ratio, manoeuvrability, cruise distance, flight control, etc. This capability is extremely beneficial since it will enable the UCAV to reconcile conflicting mission requirements (e.g. loiter and dash within the same mission). In this study, we conduct several modifications to the wing geometry of UCAV 1303 via Computational Fluid Dynamics (CFD) to analyse its aerodynamic characteristics produced by a range of different wing geometric morphs. Here we look into two specific geometric morphing wings: linear twists on one of the wings and linear twists at both wings (wash-in and washout). A baseline CFD of the UCAV 1303 without any wing morphing is validated against published wind tunnel data, before proceeding to simulate morphing wing configurations. The results show that geometric morphing wing influences the UCAV-1303 aerodynamic characteristics significantly, improving the coefficient of lift and drag, pitching moment and rolling moment.

Interactions of a streamwise-oriented vortex with a finite wing

2015 ◽  
Vol 767 ◽  
pp. 782-810 ◽  
Author(s):  
D. J. Garmann ◽  
M. R. Visbal
Keyword(s):  
Separation Bubble ◽  
Angle Of Attack ◽  
Three Dimensional ◽  
Leading Edge ◽  
Tip Vortex ◽  
Recirculation Region ◽  
Rolling Moment ◽  
Effective Angle ◽  
Finite Wing ◽  
Modes Of Interaction

AbstractA canonical study is developed to investigate the unsteady interactions of a streamwise-oriented vortex impinging upon a finite surface using high-fidelity simulation. As a model problem, an analytically defined vortex superimposed on a free stream is convected towards an aspect-ratio-six ($\mathit{AR}=6$) plate oriented at an angle of ${\it\alpha}=4^{\circ }$ and Reynolds number of $\mathit{Re}=20\,000$ in order to characterize the unsteady modes of interaction resulting from different spanwise positions of the incoming vortex. Outboard, tip-aligned and inboard positioning are shown to produce three distinct flow regimes: when the vortex is positioned outboard of, but in close proximity to, the wingtip, it pairs with the tip vortex to form a dipole that propels itself away from the plate through mutual induction, and also leads to an enhancement of the tip vortex. When the incoming vortex is aligned with the wingtip, the tip vortex is initially strengthened by the proximity of the incident vortex, but both structures attenuate into the wake as instabilities arise in the pair’s feeding sheets from the entrainment of opposite-signed vorticity into either structure. Finally, when the incident vortex is positioned inboard of the wingtip, the vortex bifurcates in the time-mean sense with portions convecting above and below the wing, and the tip vortex is mostly suppressed. The time-mean bifurcation is actually a result of an unsteady spiralling instability in the vortex core that reorients the vortex as it impacts the leading edge, pinches off, and alternately attaches to either side of the wing. The increased effective angle of attack inboard of impingement enhances the three-dimensional recirculation region created by the separated boundary layer off the leading edge which draws fluid from the incident vortex inboard and diminishes its impact on the outboard section of the wing. The slight but remaining downwash present outboard of impingement reduces the effective angle of attack in that region, resulting in a small separation bubble on either side of the wing in the time-mean solution, effectively unloading the tip outboard of impingement and suppressing the tip vortex. All incident vortex positions provide substantial increases in the wing’s lift-to-drag ratio; however, significant sustained rolling moments also result. As the vortex is brought inboard, the rolling moment diminishes and eventually switches sign as the reduced outboard loading balances the augmented sectional lift inboard of impingement.

Cavity for Flow Control and Performance Improvement of Airfoil

2021 ◽  
Author(s):  
Anand Verma ◽  
Bastav Borah ◽  
Vinayak Kulkarni
Keyword(s):  
Moving Boundary ◽  
Flow Analysis ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Suction Surface ◽  
Confined Spaces ◽  
Steady Simulation ◽  
And Performance ◽  
Lift And Drag ◽  
Fluid Flow Analysis

Abstract The fluid flow analysis over a cambered airfoil having three different cavity locations on the suction surface is reported in this paper. The Elliptical cavity is created at LE, MC, and TE along chordwise locations from the leading to trailing edge. In this regard, the steady simulation is carried out in the Fluent at Reynolds number of 105 based on their chord length. The lift and drag characteristics for clean and cavities airfoil are investigated at different angles of attack. For the clean airfoil, the stall point is observed at 18°. The presence of a cavity improves the stall and aerodynamic characteristics of airfoil. It has been seen that the lift and drag coefficients for pre-stalled or lower angles are nearly similar to clean and cavity at MC or TE positions. For the post-stall point, the improvement in the aerodynamic performance is seen for the cavity at MC or TE. The cavity placed at LE produces lower lift and higher drag characteristics against other configuration models. The overall cavity effect for the flow around the airfoil is that it creates vortices, thereby re-energizes the slower moving boundary layer and delays the flow separation in the downstream direction. The outcomes of this analysis are suggested that the cavity at a position before the mid chord from the leading edge does not improve the performance of the airfoil. Though vortex is formed in the confined spaces but it is unable to reattach the flow towards the downstream direction of an airfoil.

Investigation of aerodynamic coefficients at Mach 6 over conical, hemispherical and flat-face spiked body

2017 ◽  
Vol 121 (1245) ◽  
pp. 1711-1732 ◽  
Author(s):  
R. Kalimuthu ◽  
R. C. Mehta ◽  
E. Rathakrishnan
Keyword(s):  
Flow Field ◽  
Blunt Body ◽  
Angle Of Attack ◽  
Separated Flow ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Geometrical Parameters ◽  
Aerodynamic Coefficients ◽  
Aerodynamic Forces ◽  
Flow Field Characteristics

ABSTRACTA forward spike attached to a blunt body significantly alters its flow field characteristics and influences aerodynamic characteristics at hypersonic flow due to formation of separated flow and re-circulation region around the spiked body. An experimental investigation was performed to measure aerodynamic forces for spikes blunt bodies with a conical, hemispherical and flat-face spike at Mach 6 and at an angle-of-attack range from 0° to 8° and length-to-diameterL/Dratio of spike varies from 0.5 to 2.0, whereLis the length of the spike andDis diameter of blunt body. The shape of the leading edge of the spiked blunt body reveals different types of flow field features in the formation of a shock wave, shear layer, flow separation, re-circulation region and re-attachment shock. They are analysed with the help of schlieren pictures. The shock distance ahead of the hemisphere and the flat-face spike is compared with the analytical solution and is showing satisfactory agreement with the schlieren pictures. The influence of geometrical parameters of the spike, the shape of the spike tip and angle-of-attack on the aerodynamic coefficients are investigated by measuring aerodynamic forces in a hypersonic wind tunnel. It is found that a maximum reduction of drag of about 77% was found for hemisphere spike ofL/D= 2.0 at zero angle-of-attack. Consideration for compensation of increased pitching moment is required to stabilise the aerodynamic forces.

Stability Analysis of a Light Aircraft Configuration Using Computational Fluid Dynamics

2012 ◽  
Vol 225 ◽  
pp. 391-396 ◽  
Author(s):  
Mohammed Mahdi ◽  
Yasser A. Elhassan
Keyword(s):  
Numerical Simulation ◽  
Stokes Equations ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Rate Of Change ◽  
Navier Stokes ◽  
Rolling Moment ◽  
Moment Coefficient ◽  
Stability Derivatives ◽  
Lift And Drag

This work aims to simulate and study the flow field around SAFAT-01 aircraft using numerical solution based on solving Reynolds Averaged Navier-Stokes equations coupled with K-ω SST turbulent model. The aerodynamics behavior of SAFAT-01 aircraft developed at SAFAT aviation complex were calculated at different angles of attack and side slip angles. The x,y and z forces and moments were calculated at flight speed 50m/s and at sea level condition. Lift and drag curves for different angles of attack were plotted. The maximum lift coefficient for SAFAT-01 was 1.67 which occurred at angle of attack 16° and Maximum lift to drag ratio (L/D) was 14 which occurred at α=3°, and the zero lift drag coefficient was 0.0342. Also the yawing moment coefficient was plotted for different side slip angles as well as rolling moment. The longitudinal stability derivatives with respect to angle of attack, speed variation (u), rate of pitch (q) and time rate of change of angle of attack were calculated using obtained CFD results. Concerning lateral stability only side slips derivatives were calculated. To validate this numerical simulation USAF Digital DATCOM is used to analyze this aircraft; a comparison between predicted results for this aircraft and Digital DATCOM indicated that this numerical simulation has high ability for predicting the aerodynamics characteristics.

scholarly journals Unsteady Aerodynamic Characteristics Simulations of Rotor Airfoil under Oscillating Freestream Velocity

2020 ◽  
Vol 10 (5) ◽  
pp. 1822
Author(s):  
Qing Wang ◽  
Qijun Zhao
Keyword(s):  
Three Dimensional ◽  
Grid Method ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Critical Value ◽  
Dynamic Stall ◽  
Navier Stokes ◽  
Freestream Velocity ◽  
Unsteady Aerodynamic ◽  
Edge Vortex

The dynamic stall characteristics of rotor airfoil are researched by employing unsteady Reynolds-Averaged Navier-Stokes (RANS) method under oscillating freestream velocity conditions. In order to simulate the oscillating freestream velocity of airfoil under dynamic stall conditions, the moving-embedded grid method is employed to simulate the oscillating velocity. By comparing the simulated dynamic stall characteristics of two-dimensional airfoil and three-dimensional rotor, it is indicated that the dynamic stall characteristics of airfoil under oscillating freestream velocity reflect the actual dynamic stall characteristics of rotor airfoil in forward flight more accurately. By comparing the simulated results of OA209 airfoil under coupled freestream velocity/pitching oscillation conditions, it is indicated that the dynamic stall characteristics of airfoil associate with the critical value of Cp peaks (i.e., the dynamic stall characteristics of OA209 airfoil would be enhanced when the maximum negative pressure is larger than −1.08, and suppressed when this value is smaller than −1.08). By comparing the characteristics of vortices under different oscillating velocities, it indicates that the dissipation rate of leading edge vortex presents as exponent characteristics, and it is not sensitive to different oscillating velocities.

Experimental Aerodynamic Characteristics of a Compound Wing in Ground Effect

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Saeed Jamei ◽  
Adi Maimun Abdul Malek ◽  
Shuhaimi Mansor ◽  
Nor Azwadi Che Sidik ◽  
Agoes Priyanto
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Center Of Pressure ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Ground Effect ◽  
Reynolds Numbers ◽  
Aerodynamic Characteristics ◽  
Ground Clearance

Wing configuration is a parameter that affects the performance of wing-in-ground effect (WIG) craft. In this study, the aerodynamic characteristics of a new compound wing were investigated during ground effect. The compound wing was divided into three parts with a rectangular wing in the middle and two reverse taper wings with anhedral angle at the sides. The sectional profile of the wing model is NACA6409. The experiments on the compound wing and the rectangular wing were carried to examine different ground clearances, angles of attack, and Reynolds numbers. The aerodynamic coefficients of the compound wing were compared with those of the rectangular wing, which had an acceptable increase in its lift coefficient at small ground clearances, and its drag coefficient decreased compared to rectangular wing at a wide range of ground clearances, angles of attack, and Reynolds numbers. Furthermore, the lift to drag ratio of the compound wing improved considerably at small ground clearances. However, this improvement decreased at higher ground clearance. The drag polar of the compound wing showed the increment of lift coefficient versus drag coefficient was higher especially at small ground clearances. The Reynolds number had a gradual effect on lift and drag coefficients and also lift to drag of both wings. Generally, the nose down pitching moment of the compound wing was found smaller, but it was greater at high angle of attack and Reynolds number for all ground clearance. The center of pressure was closer to the leading edge of the wing in contrast to the rectangular wing. However, the center of pressure of the compound wing was later to the leading edge at high ground clearance, angle of attack, and Reynolds number.

scholarly journals Effect of Leading-Edge Bulges on Aerodynamic Characteristics of Bionic Wingsail

2021 ◽  
Author(s):  
Chen Li ◽  
Peiting Sun ◽  
Hongming Wang
Keyword(s):  
Stokes Equations ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Suction Surface ◽  
Ansys Fluent ◽  
Navier Stokes Equations ◽  
Extension Direction ◽  
Lift And Drag

The leading-edge bulges along the extension direction are designed on the marine wingsail. The height and the spanwise wavelength of the protuberances are 0.1c and 0.25c, respectively. At Reynolds number Re=5×105, the Reynolds Averaged Navier-Stokes equations are applied to the simulation of the wingsail with the bulges thanks to ANSYS Fluent finite-volume solver based on the SST K-ω models. The grid independence analysis is carried out with the lift and drag coefficients of the wingsail at AOA = 8° and AOA=20°. The results show that while the efficiency of the wingsail is reduced by devising the leading-edge bulges before stall, the bulges help to improve the lift coefficient of the wingsail when stalling. At AOA=22° under the action of the leading-edge tubercles, a convective vortex is formed on the suction surface of the modified wingsail, which reduces the flow loss. So the bulges of the wingsail can delay the stall.

scholarly journals Boundary Layer Control of Airfoil using Rotating Cylinder

2020 ◽  
Vol 8 (6) ◽  
pp. 4742-4750
Keyword(s):  
Leading Edge ◽  
Rotating Cylinder ◽  
Aerodynamic Characteristics ◽  
Favourable Result ◽  
Ansys Fluent ◽  
High Lift ◽  
Freestream Velocity ◽  
Aerodynamic Efficiency ◽  
Two Parameters ◽  
Layer Control

The requirement for improving the aerodynamic efficiency and delaying the formation of stall over the wing has been of prime importance within the field of aviation. The main objective of the project is to further improve upon these two parameters. The configuration used for analysis consists of a NACA 2412 airfoil of chord length 0.982m with a 64mm cylinder at the leading edge. Analysis is completed using ANSYS Fluent, with a freestream velocity of 10m/s. The aerodynamic characteristics of three configuration bare airfoil, Airfoil with static cylinder and Airfoil with rotating cylinder are tabulated and plotted. The comparison is then followed by pressure and velocity contours to visualize the flow over each configuration. The rotating cylinder configuration shows a improvement in the aerodynamics characteristics. The rotating cylinder configuration gives the most favourable result. This study has a potential application in high lift devices and can be used as stall delaying device

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