scholarly journals RESEARCH OF WING DIHEDRAL ANGLE EFFECT ON AERODYNAMIC PERFORMANCE OF TANDEM-WING UNMANNED AERIAL VEHICLE

2013 ◽  
pp. 90-101
Author(s):  
І. С. Кривохатько
Keyword(s):  
Dihedral Angle ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
Theoretical Explanation ◽  
Wing Span ◽  
Induced Drag ◽  
Rear Wing ◽  
Angle Effect ◽  
Drag Ratio ◽  
Lift To Drag Ratio

In the last decade folding tube launch UAV became common, for which aerodynamic scheme "tandem" is reasonable. By the time tandem-wing aerodynamic characteristics are researched much less than ones of traditional scheme. Particularly it concerns wing dihedral angle effect on lift-to-drag ratio about which no quantitative data were found.Forward or rear wing dihedral angle appearance result in circulation redistribution and changing of rear wing induced drag. Rear wing dihedral angle effect on longitudinal aerodynamic performance of tandem-wing UAV model was researched through wind tunnel experiment. Geometry variables were forward and rear wing spans, rear wing dihedral angle and longitudinal stagger. Lift, drag and longitudinal moment coefficients were defined.The possibility of lift-to-drag ratio increasing at cruise regime was proofed. Rear wing negative dihedral angle application is able to increase maximal lift-to-drag ratio by more than 1.0 or about 10 %.It was found that wing dihedral angle effectiveness depends from relation of forward and rear wing spans and from longitudinal stagger. Longitudinal stagger increasing results in dihedral angle effectiveness falling if forward wing span is higher than rear wing. For bigger rear wing span increasing of longitudinal stagger results in dihedral angle effectiveness gaining. The hypothesis was declared that proposes theoretical explanation of experimentally founded dependencies.Also dihedral angle appearance increases lift slope because of rear wing carrying capacity gain and has almost no influence on maximal lift coefficient.All dependencies founded for rear wing negative dihedral angle are correct for forward wing positive dihedral angle except the last one is increasing longitudinal and lateral stability.

CFD analysis of variable geometric angle winglets

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ali Hussain Kazim ◽  
Abdullah Hamid Malik ◽  
Hammad Ali ◽  
Muhammad Usman Raza ◽  
Awais Ahmad Khan ◽  
...  
Keyword(s):  
Aerodynamic Performance ◽  
Sweep Angle ◽  
Content Type ◽  
Wing Model ◽  
Induced Drag ◽  
Computational Fluid Dynamics Analysis ◽  
Attached Flow ◽  
Drag Ratio ◽  
Fuel Costs ◽  
Lift To Drag Ratio

Purpose Winglets play a major role in saving fuel costs because they reduce the lift-induced drag formed at the wingtips. The purpose of this paper is to obtain the best orientation of the winglet for the Office National d’Etudes et de Recherches Aérospatiales (ONERA) M6 wing at Mach number 0.84 in terms of lift to drag ratio. Design/methodology/approach A computational fluid dynamics analysis of the wing-winglet configuration based on the ONERA M6 airfoil on drag reduction for different attack angles at Mach 0.84 was performed using analysis of systems Fluent. First, the best values of cant and sweep angles in terms of aerodynamic performance were selected by performing simulations. The analysis included cant angle values of 30°, 40°, 45°, 55°, 60°, 70° and 75°, while for the sweep angles 35°, 45°, 55°, 65° and 75° angles were used. The aerodynamic performance was measured in terms of the obtained lift to drag ratios. Findings The results showed that slight alternations in the winglet configuration can improve aerodynamic performance for various attack angles. The best lift to drag ratio for the winglet was achieved at a cant angle of 30° and a sweep angle of 65°, which caused a 5.33% increase in the lift to drag ratio. The toe-out angle winglets as compared to the toe-in angles caused the lift to drag ratio to increase because of more attached flow at its surface. The maximum value of the lift to drag ratio was obtained with a toe-out angle (−5°) at an angle of attack 3° which was 2.53% greater than the zero-toed angle winglet. Originality/value This work is relatively unique because the cant, sweep and toe angles were analyzed altogether and led to a significant reduction in drag as compared to wing without winglet. The wing model was compared with the results provided by National Aeronautics and Space Administration so this validated the simulation for different wing-winglet configurations.

scholarly journals Numerical and Experimental Investigation on the Aerodynamic performance of roller Airfoil

2018 ◽  
Vol 7 (4.10) ◽  
pp. 637 ◽  
Author(s):  
M. Senthil Kumar ◽  
R. Vijayanandh ◽  
N. Kaviarasan ◽  
R. Dinesh Kumar ◽  
I. Adrin Issai Arasu ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Laminar Flow ◽  
Performance Enhancement ◽  
Aerodynamic Performance ◽  
Flight Performance ◽  
Induced Drag ◽  
Aerodynamic Properties ◽  
Morphing Technology ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Prevailing norm is a fixed wing in a conventional aircraft, but the prospect appears bright for developing wings that could yield better aerodynamic properties with a change in the form and shape, this may have a wider application in future aviation. The main objective of this paper is to probe such a morphing technology in wings to improve their aerodynamic performance while operating at various cruise conditions. The airfoil is equipped with a rolling mechanism on its upper surface, operated by custom- designed controllers. This roller airfoil model will generate higher lift at low angles of attack and substantially increase flight performance, leading to the evolution of a create multiple-regime, aerodynamically efficient aircraft. This paper aims to compare the performance enhancement of roller airfoil over a conventional airfoil, by increasing the velocity at the upper surface of the airfoil to increase the lift to drag ratio using typical engineering analyses. The cambered airfoil chosen here is NACA 4412. Morphing concept brings about the improvement due to a reduction in lift-induced drag by promoting large laminar flow run on the upper surface of the wing.  

Comparison between Methods of Generation of Waveriders Derived from Streamline Tracing and Simplified Method

2013 ◽  
Vol 390 ◽  
pp. 134-140
Author(s):  
Feng Ding ◽  
Jun Liu ◽  
Liang Jin ◽  
Shi Bin Luo
Keyword(s):  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
High Lift ◽  
Shape Factors ◽  
Simplified Method ◽  
Streamline Tracing ◽  
Simulation Results ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Tracing Method

Waverider with a high lift-to-drag ratio has drawn an ever increasing attention. Usually, waverider is obtained by tracing streamline. A simplified generation method of waverider is introduced in the present paper named geometric relations method. Three groups of cone-derived waverider configuration, respectively, based on the geometric relations method and the streamline tracing method are generated for the comparisons of the shape factors, inviscid aerodynamic characteristics, and flow field structures by investigating the numerical simulation results. The results show that the effect of the Mach number and the shock angle on the differences caused by the two methods are not significantly different. While the volumetric efficiency of the waverider configuration based on the geometric relations method is larger than those based on the streamline tracing, the inviscid lift-to-drag ratio of the former is less than the latter. Although the geometric relations method is much easier than the streamline tracing method, the simplified method reduces the aerodynamic performance of the waverider configuration.

scholarly journals Numerical Simulation of Flow over Bionic Airfoil

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Lishu Hao ◽  
Yongwei Gao ◽  
Binbin Wei ◽  
Ke Song
Keyword(s):  
Numerical Simulation ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
Curve Shape ◽  
Effective Angle ◽  
Trailing Edge Flap ◽  
Cfd Method ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Bionic Airfoil

In this study, the aerodynamic performance of bionic airfoil was numerically studied by CFD method. The bionic airfoil was represented by the combination of airfoil and a small trailing edge flap. A variety of configurations were calculated to study the effect of flap parameters, such as the flap angle, position, and shape, on the bionic airfoil aerodynamic characteristics based on two layouts which were that (1) there was a tiny gap between the airfoil and the flap and (2) there was no gap between the two. The results showed that the flap angle and position had significant effects on the aerodynamic performance of the airfoil with the two layouts. Compared with the clean airfoil, the maximum lift coefficients of the first layout and the second layout could be increased by 10.9% and 7.9%, respectively. And the effective angle of attack (AoA) range for improving the lift-to-drag ratio could reach 7°. The flap shape also affected the airfoil aerodynamic characteristics, and the flap with the sinusoid curve shape showed ideal performance.

Aerodynamic performance improvement of a canard control missile

2017 ◽  
Vol 89 (6) ◽  
pp. 871-878 ◽  
Author(s):  
M. Tahani ◽  
M. Masdari ◽  
M. Kazemi
Keyword(s):  
Aspect Ratio ◽  
Drag Coefficient ◽  
Cross Section ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
Slender Body Theory ◽  
Content Type ◽  
Drag Ratio ◽  
Body Theory ◽  
Lift To Drag Ratio

Purpose This paper aims to analyze the influence of the changings in geometrical parameters on the aerodynamic performance of the control canard projectiles. Design/methodology/approach Because of the mentioned point, the range of projectiles increment has a considerable importance, and the design algorithm of a control canard projectile was first written. Then, were studied the effects of canard geometric parameters such as aspect ratio, taper ratio and deflectable nose on lift to drag coefficient ratio, static margin based on the slender body theory and cross section flow. Findings The code results show that aspect ratio increment, results in an increase in lift-to-drag ratio of the missile, but increase in canard taper ratio results in increasing of lift-to-drag ratio at 1° angle of attack, while during increasing the canard taper ratio up to 0.67 at 4° angle of attack, lift to drag first reaches to maximum and then decreases. Also, static margin decreases with canard taper ratio and aspect ratio increment. The developed results for this type of missile were compared with same experimental and computational fluid dynamic (CFD) results and appreciated agreement with other results at angles of attack between 0° and 6°. Practical implications To design a control canard missile, the effect of each geometric parameter of canard needs to be estimated. For this purpose, the suitable algorithm is used. In this paper, the effects of canard geometric parameters, such as aspect ratio, taper ratio and deflectable nose on lift-to-drag coefficient ratio and static margin, were studied with help of the slender body theory and cross-section flow. Originality/value The contribution of this paper is to predict the aerodynamic characteristics for the control canard missile. In this study, the effect of the design parameter on aerodynamic characteristics can be estimated, and the effect of geometrical characteristics has been analyzed with a suitable algorithm. Also, the best lift-to-drag coefficient for the NASA Tandem Control Missile at Mach 1.75 was selected at various angles of attack. The developed results for this type of missile were compared with same experimental and CFD results.

scholarly journals Numerical study on aerodynamic performance of waverider with a new bluntness method

2020 ◽  
pp. 095441002096841
Author(s):  
Zhipeng Qu ◽  
Houdi Xiao ◽  
Mingyun Lv ◽  
Guangli Li ◽  
Cui Kai
Keyword(s):  
Numerical Study ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
The Novel ◽  
High Lift ◽  
Wide Range ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Sharp Leading Edge

Abastrct The waverider is deemed the most promising configuration for hypersonic vehicle with its high lift-to-drag ratio at design conditions. However, considering the serious aero-heating protection, the sharp leading edge must be blunted. The existing traditional bluntness methods including the following two types: “reducing material method” and “adding material method”. Compared to the initial waverider, the volume will be smaller or larger using the traditional methods. With the fixed blunted radius, the volume and aerodynamic performance is determined. In this paper, a new bluntness method which is named “mixing material method” is developed. In this new method, a new parameter is introduced based on the traditional two bluntness methods. Under fixed blunted radius, the volume and aerodynamic performance can be changed within a wide range by adjusting the parameter. When the parameter is 0 and 1, the novel blunted method degenerated into the “reducing material method” and “adding material method” respectively. The influence of new parameter on the aerodynamic characteristics and volume are studied by numerical simulation. Results show that the volume, lift and lift-to-drag ratio increases with the increase of the parameter under the fixed blunt radius, but simultaneously, the drag will also increase. Therefore, considering the different requirements of the air-breathing hypersonic aircrafts for the balance of thrust and drag, lift and weight, a suitable bluntness parameter can be selected to achieve a balance. This research can provide reference for hypersonic waverider vehicle design.

Aerodynamic study of single corrugated variable-camber morphing aerofoil concept

2021 ◽  
pp. 1-29
Author(s):  
K. Dhileep ◽  
D. Kumar ◽  
P.N. Gautham Vigneswar ◽  
P. Soni ◽  
S. Ghosh ◽  
...  
Keyword(s):  
Finite Volume ◽  
Interpolation Method ◽  
Beam Theory ◽  
Small Deformation ◽  
Aerodynamic Characteristics ◽  
Ansys Fluent ◽  
Aerodynamic Efficiency ◽  
Finite Element Software ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Abstract Camber morphing is an effective way to control the lift generated by any aerofoil and potentially improve the range (as measured by the lift-to-drag ratio) and endurance (as measured by $C_l^{3/2}/C_d$ ). This can be especially useful for fixed-wing Unmanned Aerial Vehicles (UAVs) undergoing different flying manoeuvres and flight phases. This work investigates the aerodynamic characteristics of the NACA0012 aerofoil morphed using a Single Corrugated Variable-Camber (SCVC) morphing approach. Structural analysis and morphed shapes are obtained based on small-deformation beam theory using chain calculations and validated using finite-element software. The aerofoil is then reconstructed from the camber line using a Radial Basis Function (RBF)-based interpolation method (J.H.S. Fincham and M.I. Friswell, “Aerodynamic optimisation of a camber morphing aerofoil,” Aerosp. Sci. Technol., 2015). The aerodynamic analysis is done by employing two different finite-volume solvers (OpenFOAM and ANSYS-Fluent) and a panel method code (XFoil). Results reveal that the aerodynamic coefficients predicted by the two finite-volume solvers using a fully turbulent flow assumption are similar but differ from those predicted by XFoil. The aerodynamic efficiency and endurance factor of morphed aerofoils indicate that morphing is beneficial at moderate to high lift requirements. Further, the optimal morphing angle increases with an increase in the required lift. Finally, it is observed for a fixed angle-of-attack that an optimum morphing angle exists for which the aerodynamic efficiency becomes maximum.

scholarly journals Aerodynamic and Vibration Characteristics of the Micro-Octocopter at Low Reynolds Number

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xiaohua Zou ◽  
Mingsheng Ling ◽  
Wenzheng Zhai
Keyword(s):  
Reynolds Number ◽  
Load Capacity ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Vibration Characteristics ◽  
Low Reynolds ◽  
Vibration Performance ◽  
Drag Ratio ◽  
Lift To Drag Ratio

With the development of flight technology, the need for stable aerodynamic and vibration performance of the aircraft in the civil and military fields has gradually increased. In this case, the requirements for aerodynamic and vibration characteristics of the aircraft have also been strengthened. The existing four-rotor aircraft carries limited airborne equipment and payload, while the current eight-rotor aircraft adopts a plane layout. The size of the propeller is generally fixed, including the load capacity. The upper and lower tower layout analyzed in this paper can effectively solve the problems of insufficient four-axis load and unstable aerodynamic and vibration performance of the existing eight-axis aircraft. This paper takes the miniature octorotor as the research object and studies the aerodynamic characteristics of the miniature octorotor at different low Reynolds numbers, different air pressures and thicknesses, and the lift coefficient and lift-to-drag ratio, as well as the vibration under different elastic moduli and air pressure characteristics. The research algorithm adopted in this paper is the numerical method of fluid-solid cohesion and the control equation of flow field analysis. The research results show that, with the increase in the Reynolds number within a certain range, the aerodynamic characteristics of the miniature octorotor gradually become better. When the elastic modulus is 2.5 E, the aircraft’s specific performance is that the lift increases, the critical angle of attack increases, the drag decreases, the lift-to-drag ratio increases significantly, and the angle of attack decreases. However, the transition position of the flow around the airfoil surface is getting closer to the leading edge, and its state is more likely to transition from laminar flow to turbulent flow. When the unidirectional carbon fiber-reinforced thickness is 0.2 mm and the thin arc-shaped airfoil with the convex structure has a uniform thickness of 2.5% and a uniform curvature of 4.5%, the aerodynamic and vibration characteristics of the octorotor aircraft are most beneficial to flight.

Kinematics of diving Atlantic puffins (Fratercula arctica L.):evidence for an active upstroke

2002 ◽  
Vol 205 (3) ◽  
pp. 371-378
Author(s):  
L. Christoffer Johansson ◽  
Björn S. Wetterholm Aldrin
Keyword(s):  
Three Dimensional ◽  
Fratercula Arctica ◽  
Induced Drag ◽  
Video Images ◽  
Hand Bones ◽  
On Line ◽  
Oscillating Motion ◽  
Drag Ratio ◽  
Wing Tip ◽  
Lift To Drag Ratio

SUMMARY To examine the propulsion mechanism of diving Atlantic puffins (Fratercula arctica), their three-dimensional kinematics was investigated by digital analysis of sequential video images of dorsal and lateral views. During the dives of this wing-propelled bird, the wings are partly folded, with the handwings directed backwards. The wings go through an oscillating motion in which the joint between the radius-ulna and the hand bones leads the motion, with the wing tip following. There is a large rotary motion of the wings during the stroke, with the wings being pronated at the beginning of the downstroke and supinated at the end of the downstroke/beginning of the upstroke. Calculated instantaneous velocities and accelerations of the bodies of the birds show that, during the downstroke, the birds accelerate upwards and forwards. During the upstroke, the birds accelerate downwards and, in some sequences analysed, also forwards, but in most cases the birds decelerate. In all the upstrokes analysed, the forward/backward acceleration shows the same pattern, with a reduced deceleration or even a forward acceleration during ‘mid’ upstroke indicating the production of a forward force, thrust. Our results show that the Atlantic puffin can use an active upstroke during diving, in contradiction to previous data. Furthermore, we suggest that the partly folded wings of diving puffins might act as efficient aft-swept wingtips, reducing the induced drag and increasing the lift-to-drag ratio. A movie is available on-line.

The aerodynamic optimisation of a low-Reynolds paper plane with adjoint method

2020 ◽  
pp. 1-15
Author(s):  
Y. Zhang ◽  
X. Zhang ◽  
G. Chen
Keyword(s):  
Adjoint Method ◽  
Low Cost ◽  
Aerodynamic Performance ◽  
Discrete Adjoint ◽  
Design Variables ◽  
Limited Variation ◽  
Aerial Vehicle ◽  
Paper Plane ◽  
Drag Ratio ◽  
Lift To Drag Ratio

ABSTRACT The aerodynamic performance of a deployable and low-cost unmanned aerial vehicle (UAV) is investigated and improved in present work. The parameters of configuration, such as airfoil and winglet, are determined via an optimising process based on a discrete adjoint method. The optimised target is locked on an increasing lift-to-drag ratio with a limited variation of pitching moments. The separation that will lead to a stall is delayed after optimisation. Up to 128 design variables are used by the optimised solver to give enough flexibility of the geometrical transformation. As much as 20% enhancement of lift-to-drag ratio is gained at the cruise angle-of-attack, that is, a significant improvement in the lift-to-drag ratio adhering to the preferred configuration is obtained with increasing lift and decreasing drag coefficients, essentially entailing an improved aerodynamic performance.

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