Lift Distribution and Lift-Induced Drag Ratio of a Finite Wing in an Infinite Cascade

1962 ◽  
Vol 66 (624) ◽  
pp. 785-789
Author(s):  
B. Lakshminarayana
Keyword(s):  
Induced Drag ◽  
Previous Note ◽  
Trailing Vortices ◽  
Circulation Distribution ◽  
Finite Wing ◽  
Drag Ratio

In a recent note a method was developed for calculating the reduction in average lift of a cascade aerofoil due to trailing vortices, neglecting the interference due to blockage and stream curvature. Using the numerical values (for a rectangular aerofoil in an unstaggered cascade of finite wings) of the coefficients in the series for the circulation distribution obtained from the Liverpool University DEUCE programme referred to in the previous note, the effect of interference on the spanwise lift distribution has been studied. The analysis has been extended to predict the lift-induced drag ratio of a finite wing in a cascade.

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 force on a slender fish-like body

1973 ◽  
Vol 58 (4) ◽  
pp. 689-702 ◽  
Author(s):  
J. N. Newman
Keyword(s):  
Vortex Sheet ◽  
Inviscid Flow ◽  
The Body ◽  
Flux Analysis ◽  
Propulsive Force ◽  
Pressure Force ◽  
Induced Drag ◽  
The Mean ◽  
Axisymmetric Bodies ◽  
Drag Ratio

The force acting on a fish-like body with combined thickness and lifting effects is analysed on the assumption of inviscid flow. A general expression is developed for the pressure force on the body, which is analogous to the momentum-flux analysis for non-lifting bodies in classical hydrodynamics. For bodies with constant volume, the mean drag (or propulsive) force is expressed in terms of a contour integral around the vortex sheet behind the body. Attention is focused on the case of steady-state motion with constant angle of attack, and the induced drag is analysed for finned axisymmetric bodies using the slender-body approximation developed by Newman & Wu (1973). Unlike earlier results of Lighthill (1970), the lift–drag ratio in this case depends on the body thickness.

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.  

A Wind-Tunnel Study of Gliding Flight in the Pigeon Columba Livia

1968 ◽  
Vol 49 (3) ◽  
pp. 509-526 ◽  
Author(s):  
C. J. PENNYCUICK
Keyword(s):  
Wind Tunnel ◽  
Columba Livia ◽  
Wing Area ◽  
Total Drag ◽  
Induced Drag ◽  
Wing Profile ◽  
Gliding Flight ◽  
Lift And Drag ◽  
Wind Tunnel Study ◽  
Drag Ratio

1. A technique for training pigeons to fly in a tilting wind tunnel is described, and a method of determining lift and drag in gliding flight is explained. 2. Drag measurements were made on wingless bodies and preserved feet in supplementary experiments. The results were used to analyse the measured total drag of live pigeons into (a) body drag, (b) foot drag, (c) induced drag, and (d) wing profile drag. 3. As speed is increased, gliding pigeons drastically reduce their wing span, wing area and aspect ratio. The increased induced drag resulting from this is more than offset by a very large reduction in wing profile drag. 4. Although the lift: drag ratio is at best 5.5-6.0, changes of wing area and shape keep it near its maximum, up to speeds at least twice the minimum gliding speed.

scholarly journals Effect of vortex dynamics and instability characteristics on the induced drag of trailing vortices

2021 ◽  
Author(s):  
Zepeng Cheng ◽  
Shiyan Zhang ◽  
Yang Xiang ◽  
Chun Shao ◽  
Miao Zhang ◽  
...  
Keyword(s):  
Vortex Dynamics ◽  
Induced Drag ◽  
Trailing Vortices

Effects of Tunable Angle for Vortex Generators on Aerodynamic Performances of Airfoils

2017 ◽  
Vol 872 ◽  
pp. 192-197
Author(s):  
Hu Yu ◽  
Bin Tang Yang ◽  
Xiao Qing Sun ◽  
Xi Wang ◽  
Hang Jie Mo
Keyword(s):  
Numerical Simulations ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Vortex Generators ◽  
Installation Angle ◽  
Fluctuation Phenomenon ◽  
Aerodynamic Performances ◽  
Finite Wing ◽  
Three Dimensional Models ◽  
Drag Ratio

Vortex generators (VGs) are commonly adopted to control the flow separation, and many researches have investigated their effects on the aerodynamic performance of wind turbines. However, nearly no attentions are paid to the VGs’ installation angle. Thus, in this paper, to investigate the effects of the VGs’ installation angle on airfoils, numerical simulations are conducted by CFD on the finite wing of NACA0012. According to the finite airfoil with or without VGs, three-dimensional models are established and numerical simulations are carried out in detail. It could be seen clearly that the VGs’ installation angle produces a significant impact on the aerodynamic performances. For some installation angles, special ranging from 45° to 90°, VGs can improve the lift-drag ratio apparently, even by 34.5%. While angle ranges from 15° to 30°, VGs negatively influence the lift-drag ratio. Furthermore, the fluctuation phenomenon is discussed through analysis of the streamlines and vortices. Based on those results, optimal aerodynamic performances could be achieved by the active control of the VGs’ installation angle.

Investigation on Aerodynamic Configuration of Monitoring Long Endurance UAV

2014 ◽  
Vol 509 ◽  
pp. 80-85
Author(s):  
Dong Li Ma ◽  
Yu Hang Qiao ◽  
Mu Qing Yang
Keyword(s):  
Design Method ◽  
General Scheme ◽  
Twist Angle ◽  
Weather Condition ◽  
Control Surface ◽  
Induced Drag ◽  
Bad Weather ◽  
Long Endurance ◽  
Drag Ratio ◽  
Aerodynamic Configuration

In recent years, monitoring long endurance UAV is widely used in civil fields such as earthquake relief, it has certain particularities in comparison with conventional UAV; this paper studied and summarized its key technologies in aerodynamic configuration. The research of aerodynamic configuration is based on a general scheme, research indicates that: (1) monitoring long endurance UAV has the characteristics of low-Reynolds number, so laminar airfoil is needed to increase lift-drag ratio; induced drag can be reduced by optimizing wing twist angle; (2) subsection control surface and new design method on flight-quality would improve control reliability and flight quality, which are indispensable for the UAV to guarantee safety in bad weather condition; (3) take-off/landing/taxiing performance should be considered in order to improve the runway adaptability of the UAV.

Aerodynamic Properties of Avian Flight as a Function of Wing Shape

2005 ◽  
Author(s):  
Andrew I. March ◽  
Charles W. Bradley ◽  
Ephraim Garcia
Keyword(s):  
Bird Species ◽  
Commercial Aircraft ◽  
Morphing Aircraft ◽  
Avian Flight ◽  
Induced Drag ◽  
Aerodynamic Properties ◽  
Flight Regimes ◽  
Long Endurance ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Presently, all man-made aircraft are optimized for one specific flight regime. Commercial aircraft fly at a specific cruising altitude at which they are most efficient, and military aircraft, which require excellent performance in many flight regimes are designed to be ‘good’ at all of them. A new concept in aviation, morphing aircraft, or aircraft that can fully change their shape, will allow for optimization at nearly any flight regime. This concept has been millennia in the making, well before mankind. Looking to various bird species, tails and wings can completely change shape to optimize their morphology for a given flight regime. Raptors, especially, have mastered the air in that they must out compete and overcome other birds while hunting. For soaring, these birds spread their wings fully to maximize their lift to drag ratio and maintain a low energy, long endurance flight. To maximize speed in a dive they will bring their wings close to their bodies to minimize drag. This study seeks to quantify the aerodynamic properties of the wing. From bird wings the aerodynamic properties of shape changing elastic structures can be understood. The coefficient of lift versus angle of attack plot of a bird wing is not like that of a typical airfoil, it has no distinct point where the wing stalls, instead the bird wing will twist into the flow. Additionally, the induced drag of an avian wing is significantly less than the theoretical induced drag on a wing predicted by the aspect ratio. A flow visualization around the slotted wingtips of a bird reveals smooth streaklines near the primary feathers. These feathers are canted downward and accordingly generate lift in the thrust direction of the wing, which acts to reduce the induced drag on the wing.

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