scholarly journals EXPERIMENTAL STUDY OF GROUND EFFECT ON THREE-DIMENSIONAL INSECT-LIKE FLAPPING MOTION

2014 ◽  
Vol 34 ◽  
pp. 1460384 ◽  
Author(s):  
XIAOHU ZHANG ◽  
KIM BOON LUA ◽  
RONG CHANG ◽  
TEE TAI LIM ◽  
KHOON SENG YEO
Keyword(s):  
Three Dimensional ◽  
Ground Effect ◽  
Flapping Wing ◽  
Water Tank ◽  
Force Measurements ◽  
Flapping Motion ◽  
Large Water ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Flapping Mechanism

This paper focuses on an experimental investigation aimed at evaluating the aerodynamics force characteristics of three-dimensional (3D) insect-like flapping motion in the vicinity of ground. The purpose is to establish whether flapping wing insects can derive aerodynamic benefit from ground effect similar to that experienced by a fixed wing aircraft. To evaluate this, force measurements were conducted in a large water tank using a 3D flapping mechanism capable of executing various insect flapping motions. Here, we focus on three types of flapping motions, namely simple harmonic flapping motion, hawkmoth-like hovering motion and fruitfly-like hovering motion, and two types of wing planforms (i.e. hawkmoth-like wing and fruitfly-like wing). Results show that hawkmoth-like wing executing simple harmonic flapping motion produces average lift to drag ratio [Formula: see text] similar to that of fruitfly wing executing the same motion. In both cases, they are relatively independent of the wing distance from the ground. On the other hand, a hawkmoth wing executing hawkmoth flapping motion produces [Formula: see text] characteristic different from that of fruitfly wing executing fruitfly motion. While the [Formula: see text] value of the former is a function of the wing distance from the ground, the latter is minimally affected by ground effect. Unlike fixed wing aerodynamics, all the flapping wing cases considered here do not show a monotonic increase in [Formula: see text] with decreasing wing distance from the ground.

Design of a Bio-Inspired Spherical Four-Bar Mechanism for Flapping-Wing Micro Air-Vehicle Applications

2008 ◽  
Author(s):  
Matt McDonald ◽  
Sunil K. Agrawal
Keyword(s):  
Three Dimensional ◽  
Micro Air Vehicles ◽  
Aerodynamic Performance ◽  
Flapping Wing ◽  
Micro Air Vehicle ◽  
Aerodynamic Forces ◽  
Flapping Motion ◽  
Wing Motion ◽  
Air Vehicle ◽  
Flapping Mechanism

Design of flapping-wing micro air-vehicles presents many engineering challenges. As observed by biologists, insects and birds exhibit complex three-dimensional wing motions. It is believed that these unique patterns of wing motion create favorable aerodynamic forces that enable these species to fly forward, hover, and execute complex motions. From the perspective of micro air-vehicle applications, extremely lightweight designs that accomplish these motions of the wing, using just a single, or a few actuators, are preferable. This paper presents a method to design a spherical four-bar flapping mechanism that approximates a given spatial flapping motion of a wing, considered to have favorable aerodynamics. A spherical flapping mechanism was then constructed and its aerodynamic performance was compared to the original spatially moving wing using an instrumented robotic flapper with force sensors.

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.

Numerical exploration on drag and heat reduction mechanism of a spike-tipped supersonic blunt nose

2020 ◽  
Vol 34 (32) ◽  
pp. 2050370
Author(s):  
Yu-Shan Meng ◽  
Li Yan ◽  
Shi-Bin Li ◽  
Wei Huang
Keyword(s):  
Heat Flux ◽  
Drag Force ◽  
Stokes Equations ◽  
Angle Of Attack ◽  
Three Dimensional ◽  
Viscous Force ◽  
Reduction Mechanism ◽  
Complex Flow ◽  
Drag Ratio ◽  
Lift To Drag Ratio

In this study, the drag force and heat flux reduction mechanism induced by the aerodisk (with disks on its nose) with the freestream Mach number being 4.937 has been numerically investigated, and the simulations have been carried out by the three-dimensional Reynolds-averaged Navier–Stokes equations coupled with the SST [Formula: see text] turbulence model. The influence of the angle of attack on the drag and heat flux reduction has been analyzed comprehensively. The obtained results show that the drag force of the spiked blunt body can be reduced by the aerodisk, and the drag force decreases by 24.63%. The flow mechanism of the complex flow is drastically modified by the angle of attack, and this results in a strong flow asymmetry. This asymmetry becomes more and more obvious as the angle of attack increases. Both the pressure force and viscous force increase with the increase of the angle of attack. Moreover, both the lift and drag coefficients increase as the angle of attack increases, and the lift-to-drag ratio increases first and then decreases with the increase of the angle of attack. When the angle of attack is [Formula: see text], the maximum lift-to-drag ratio is close to 0.36.

Static Stability of a Compound Wing Configuration in Ground Effect

2014 ◽  
Vol 69 (7) ◽  
Author(s):  
Saeed Jamei ◽  
Adi Maimun ◽  
M. Mobassher Tofa ◽  
Nor Azwadi ◽  
Shuhaimi Mansor ◽  
...  
Keyword(s):  
Experimental Data ◽  
Deep Understanding ◽  
Ground Effect ◽  
Static Stability ◽  
Main Concern ◽  
Turbulent Model ◽  
The Stability ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Wing In Ground Effect

The height static stability of a wing can be a main concern for conceptual design of wing-in-ground effect (WIG) crafts. In this research, the stability of a rectangular and compound wing was computationally predicted in ground effect. A realizable k-ε turbulent model was used for simulation the flow filed over the wing surfaces. First, the drag coefficient and lift to drag ratio of numerical simulation were validated by experimental data of the rectangular wing. Next, the stability of the compound wing respect to different ground clearances will be determined and compared with rectangular wing. This study illustrated a deep understanding of static stability of present compound wing in ground effect, which eventually can be a guideline for researchers and designers of WIG craft.

Making Air Travelling More Economical, An Innovative Drag Reduction Approach For A Supercritical Wing Section Using Shock Control Bumps

2014 ◽  
Vol 1 (1) ◽  
pp. 215-220
Author(s):  
A Saeed ◽  
Malik. S. Raza ◽  
Ahmed Mohsin Khalil
Keyword(s):  
Drag Reduction ◽  
Three Dimensional ◽  
Wave Drag ◽  
Two Dimensional ◽  
Supercritical Airfoil ◽  
Shock Control ◽  
Wing Section ◽  
First Choice ◽  
Drag Ratio ◽  
Lift To Drag Ratio

AbstractAir travelling is the second largest travelling medium used by people. In future it is expected to be the first choice for the travellers. As increase in the price of oil cost of air travelling is getting higher. Engineers are forced to find the cheaper means of travelling by innovating new techniques. This paper presents the new idea to reduce air travelling cost by reducing drag, which is major driving factor of high fuel consumption. Two-dimensional and three-dimensional shock control contour bumps have been designed and analysed for a supercritical wing section with the aim of transonic wave drag reduction. A supercritical airfoil (NACA SC (02)-0714) has been selected for this study considering the fact that most modern jet transport aircraft that operate in the transonic flow regime (cruise at transonic speeds) employ supercritical airfoil sections. It is to be noted that a decrease in the transonic wave drag without loss in lift would result in an increased lift to drag ratio, which being a key range parameter could potentially increase both the range and endurance of the aircraft. The major geometric bump parameters such as length, height, crest and span have been altered for both the two-dimensional and three-dimensional bumps in order to obtain the optimum location and shape of the bump. Once an optimum standalone three-dimensional bump has been acquired an array of bumps has been manually placed spanwise of an unswept supercritical wing and analysed under fully turbulent flow conditions. Different configurations have been tested with varying three-dimensional bump spacing in order to determine the contribution of bump spacing on overall performance. The results show a 14 percent drag reduction and a consequent 16 percent lift to drag ratio rise at the design Mach number for the optimum arrangement of bumps along the wing span. This innovative technique proves to be a bridge between economical problems and engineering solutions and a milestone for aviation engineering.

Analysis of Hydrophobic Painting in Model-Scale Marine Propeller

2018 ◽  
Author(s):  
Eduardo Tadashi Katsuno ◽  
Joao Lucas Dozzi Dantas ◽  
Emilio Carlos Nelli Silva
Keyword(s):  
Superhydrophobic Surface ◽  
Slip Length ◽  
Three Dimensional ◽  
Efficiency Gain ◽  
Suction Pressure ◽  
Two Dimensional ◽  
Marine Propeller ◽  
Model Scale ◽  
Drag Ratio ◽  
Lift To Drag Ratio

This paper aims to perform a numerical analysis of application effects of a superhydrophobic paint by completely coating the blades of a model-scale marine propeller in order to make it a superhydrophobic surface (SHS). First, a two-dimensional study was conducted. Two foils were analyzed for several hydrophobic conditions, varying the slip length. Pressure and skin friction distributions were shown. There is an increase of lift-to-drag ratio with hydrophobicity, but followed by an increase in suction pressure. In three-dimensional case, a propeller was simulated for several hydrophobic conditions, comparing thrust, torque and efficiency coefficients and pressure and friction distribution. Results with propeller showed that an increase in slip length is not always followed by an increase in efficiency, with an apparent efficiency gain limit. For the imposed simulation conditions, from the limit of gain, efficiency no longer increases with hydrophobicity, but its area of low pressure continues to grow.

scholarly journals Shape Optimization of an Airfoil in Ground Effect for Application to WIG Craft

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Yilei He ◽  
Qiulin Qu ◽  
Ramesh K. Agarwal
Keyword(s):  
Genetic Algorithm ◽  
Flow Field ◽  
Lift Coefficient ◽  
Ground Effect ◽  
Navier Stokes ◽  
Ansys Fluent ◽  
Multiobjective Genetic Algorithm ◽  
Lift And Drag ◽  
Drag Ratio ◽  
Lift To Drag Ratio

This paper employs a multiobjective genetic algorithm (MOGA) to optimize the shape of a widely used wing in ground (WIG) aircraft airfoil NACA 4412 to improve its lift and drag characteristics, in particular to achieve two objectives, that is, to increase its lift and its lift to drag ratio. The commercial software ANSYS FLUENT is employed to calculate the flow field on an adaptive structured mesh generated by ANSYS ICEM software using the Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with a one equation Spalart-Allmaras (SA) turbulence model. The results show significant improvement in both the lift coefficient and lift to drag ratio of the optimized airfoil compared to the original NACA 4412 airfoil. It is demonstrated that the performance of a wing in ground (WIG) aircraft can be improved by using the optimized airfoil.

scholarly journals Experimental Investigation of a Wing-in-Ground Effect Craft

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
M. Mobassher Tofa ◽  
Adi Maimun ◽  
Yasser M. Ahmed ◽  
Saeed Jamei ◽  
Agoes Priyanto ◽  
...  
Keyword(s):  
Research Work ◽  
Ground Effect ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Efficiency ◽  
Ground Clearance ◽  
Drag Forces ◽  
Lift And Drag ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Wing In Ground Effect

The aerodynamic characteristics of the wing-in-ground effect (WIG) craft model that has a noble configuration of a compound wing was experimentally investigated and Universiti Teknologi Malaysia (UTM) wind tunnel with and without endplates. Lift and drag forces, pitching moment coefficients, and the centre of pressure were measured with respect to the ground clearance and the wing angle of attack. The ground effect and the existence of the endplates increase the wing lift-to-drag ratio at low ground clearance. The results of this research work show new proposed design of the WIG craft with compound wing and endplates, which can clearly increase the aerodynamic efficiency without compromising the longitudinal stability. The use of WIG craft is representing an ambitious technology that will help in reducing time, effort, and money of the conventional marine transportation in the future.

Vortex development on pitching plates with lunate and truncate planforms

2013 ◽  
Vol 732 ◽  
pp. 332-344 ◽  
Author(s):  
Colin Hartloper ◽  
David E. Rival
Keyword(s):  
Vortex Formation ◽  
Three Dimensional ◽  
Leading Edge ◽  
Strongly Correlated ◽  
Near Wake ◽  
Relaxation Phase ◽  
Force Relaxation ◽  
Edge Vortex ◽  
Drag Ratio ◽  
Lift To Drag Ratio

AbstractThe three-dimensional flow field and instantaneous forces are measured on pitching rectangular, lunate and truncate planforms of aspect-ratio four. The leading-edge vortex on the rectangular planform is compressed as it grows, and subsequently forms an arch-shaped vortex. For the lunate and truncate planforms, which both have identical spanwise leading-edge curvature but differ in planform area, outboard-directed convection of vorticity, rather than vortex stretching, mitigates arch-vortex formation. The vortical near wake that is formed by the planforms with spanwise leading-edge curvature is found to be strongly correlated with a favourable lift-to-drag ratio during the force-relaxation phase.

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