Influence of leading edge tubercles on aerodynamic characteristics of a high aspect-ratio UAV

2017 ◽  
Vol 69 ◽  
pp. 281-289 ◽  
Author(s):  
S. Sudhakar ◽  
N. Karthikeyan ◽  
L. Venkatakrishnan
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Leading Edge ◽  
Aerodynamic Characteristics

An experimental parametric study on planar sheared wings tip devices for low-to-moderate aspect ratio wings

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Lourelay Moreira dos Santos ◽  
Guilherme Ferreira Gomes ◽  
Rogerio F. Coimbra
Keyword(s):  
Wind Tunnel ◽  
Aspect Ratio ◽  
Parametric Study ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Sweep Angle ◽  
Wind Tunnel Tests ◽  
Content Type ◽  
Wing Tips ◽  
Wing Tip

Purpose The purpose of this study is to investigate the aerodynamic characteristics of a low-to-moderate-aspect-ratio, tapered, untwisted, unswept wing, equipped of sheared wing tips. Design/methodology/approach In this work, wind tunnel tests were made to study the influence in aerodynamic characteristics over a typical low-to-moderate-aspect-ratio wing of a general aviation aircraft, equipped with sheared – swept and tapered planar – wing tips. An experimental parametric study of different wing tips was tested. Variations in its leading and trailing edge sweep angle as well as variations in wing tip taper ratio were considered. Sheared wing tips modify the flow pattern in the outboard region of the wing producing a vortex flow at the wing tip leading edge, enhancing lift at high angles of attack. Findings The induced drag is responsible for nearly 50% of aircraft total drag and can be reduced through modifications to the wing tip. Some wing tip models present complex geometries and many of them present benefits in particular flight conditions. Results have demonstrated that sweeping the wing tip leading edge between 60 and 65 degrees offers an increment in wing aerodynamic efficiency, especially at high lift conditions. However, results have demonstrated that moderate wing tip taper ratio (0.50) has better aerodynamic benefits than highly tapered wing tips (from 0.25 to 0.15), even with little less wing tip leading edge sweep angle (from 57 to 62 degrees). The moderate wing tip taper ratio (0.50) offers more wing area and wing span than the wings with highly tapered wing tips, for the same aspect ratio wing. Originality/value Although many studies have been reported on the aerodynamics of wing tips, most of them presented complex non-planar geometries and were developed for cruise flight in high subsonic regime (low lift coefficient). In this work, an exploration and parametric study through wind tunnel tests were made, to evaluate the influence in aerodynamic characteristics of a low-to-moderate-aspect-ratio, tapered, untwisted, unswept wing, equipped of sheared wing tips (wing tips highly swept and tapered).

scholarly journals Power reduction and the radial limit of stall delay in revolving wings of different aspect ratio

2015 ◽  
Vol 12 (105) ◽  
pp. 20150051 ◽  
Author(s):  
Jan W. Kruyt ◽  
GertJan F. van Heijst ◽  
Douglas L. Altshuler ◽  
David Lentink
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Angle Of Attack ◽  
Radial Distance ◽  
Leading Edge ◽  
High Angle ◽  
High Angle Of Attack ◽  
Low Aspect Ratio ◽  
Aspect Ratios ◽  
Low Aspect Ratio Wings

Airplanes and helicopters use high aspect ratio wings to reduce the power required to fly, but must operate at low angle of attack to prevent flow separation and stall. Animals capable of slow sustained flight, such as hummingbirds, have low aspect ratio wings and flap their wings at high angle of attack without stalling. Instead, they generate an attached vortex along the leading edge of the wing that elevates lift. Previous studies have demonstrated that this vortex and high lift can be reproduced by revolving the animal wing at the same angle of attack. How do flapping and revolving animal wings delay stall and reduce power? It has been hypothesized that stall delay derives from having a short radial distance between the shoulder joint and wing tip, measured in chord lengths. This non-dimensional measure of wing length represents the relative magnitude of inertial forces versus rotational accelerations operating in the boundary layer of revolving and flapping wings. Here we show for a suite of aspect ratios, which represent both animal and aircraft wings, that the attachment of the leading edge vortex on a revolving wing is determined by wing aspect ratio, defined with respect to the centre of revolution. At high angle of attack, the vortex remains attached when the local radius is shorter than four chord lengths and separates outboard on higher aspect ratio wings. This radial stall limit explains why revolving high aspect ratio wings (of helicopters) require less power compared with low aspect ratio wings (of hummingbirds) at low angle of attack and vice versa at high angle of attack.

The aeroelastic characteristics of high aspect ratio wing

2016 ◽  
Vol 230 (14) ◽  
pp. 2543-2556
Author(s):  
Fan Yang ◽  
Zhufeng Yue ◽  
Lei Li
Keyword(s):  
Aspect Ratio ◽  
Large Deformation ◽  
High Aspect Ratio ◽  
Data Exchange ◽  
Stokes Equations ◽  
Great Influence ◽  
Aerodynamic Characteristics ◽  
Interface Problem ◽  
Numerical Result ◽  
Computational Structural Mechanics

Owing to the elasticity, the large deformation was brought in the high aspect ratio wing in the flight. The large deformation had a great influence on the flight performance. In this paper, the loosely coupled method was used for the research of high aspect ratio wing aeroelastic problems. The Navier–Stokes equations were solved for fluid domain computation, and the nonlinear finite element method was adopted for solid domain computation. The data exchange program and mesh regeneration progress were adopted for fluid–structure interface problem. Finally, the aerodynamic characteristics of high aspect ratio wing were obtained under different fly conditions. In addition, to validate the proposed method, the flutter analysis of AGARD 445.6 wing is carried out and compared with the experimental data. The numerical result validates the proposed computational fluid dynamics/computational structural mechanics method.

Static Aeroelasticity Analysis of High Aspect Ratio Wing and the Jig-Shape Design Based on Multi-Block Structural Grid

2013 ◽  
Vol 302 ◽  
pp. 377-383 ◽  
Author(s):  
Yan Liu ◽  
Jun Qiang Bai ◽  
Jun Hua
Keyword(s):  
Aspect Ratio ◽  
Design Process ◽  
High Aspect Ratio ◽  
Design Method ◽  
Aerodynamic Characteristics ◽  
Shape Design ◽  
Transport Aircraft ◽  
Mesh Motion ◽  
Static Aeroelasticity ◽  
Motion Method

The influence of structural elastic deformation on the aerodynamic characterisitcs of large transport aircraft has been researched. A method of static aeroelasticity based on multi-block structural grid of high aspect ratio wing has been established, and then a design method of jig-shape is developed. The technology of RBF interpolation is used to exchange the data of CFD/CSD. Based on RBF&Delaunay technology, a mesh motion method is developed to make the design process less time-consuming, which can be applied to large deformation of multi-block structural grid. The static aeroelastic deformation of a wing-body of large transport aircraft is analyzed. Then the wing-body's jig-shape is designed. Compared the aerodynamic characteristics between design cruise shape and target cruise shape, it shows that the aerodynamic characteristics of design cruise shape is almost equal to target cruise shape and the design process of jig-shape is feasible.

Perspective: Unsteady Wing Theory—The Ka´rma´n/Sears Legacy

1993 ◽  
Vol 115 (4) ◽  
pp. 548-560 ◽  
Author(s):  
J. E. McCune ◽  
T. S. Tavares
Keyword(s):  
Aspect Ratio ◽  
Small Amplitude ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Unsteady Motion ◽  
Low Aspect Ratio ◽  
Key Concepts ◽  
Edge Separation ◽  
Point Of Departure ◽  
Large Amplitude Motion

The aerodynamic analysis of wings and their vortex wakes is discussed from a perspective of its relation to the 1938 work of Ka´rma´n and Sears. The key concepts from this early paper on the analysis of airfoils in small amplitude unsteady motion are reviewed. These concepts are then used as a point of departure for developing techniques for calculating and interpreting the aerodynamic characteristics of both airfoils in large amplitude motion with deforming vortex wakes, and maneuvering low-aspect-ratio wings with leading-edge separation. Calculated examples are presented for this extended set of applications, and are compared to related analyses and experiments.

scholarly journals AERO DYNAMIC SHAPE OF TRANSPORT AIRCRAFT “FLYING WING” SCHEME WITH HIGH ASPECT RATIO

2014 ◽  
pp. 84-92
Author(s):  
Олег Львович Лемко ◽  
Євген О. Кушніренко
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Aerodynamic Characteristics ◽  
Design Parameters ◽  
Scientific Methods ◽  
Transport Aircraft ◽  
Research Problems ◽  
And Performance ◽  
Forming Methods ◽  
Dynamic Shape

"Normal" aerodynamic scheme despite the fact that it has become the dominant in global aviation, in terms of aerodynamics is not ideal. To create a lifting force only wing is just necessary. All other elements of aircraft glider - fuselage , horizontal and vertical tail exist only for the crew, passengers and cargo, ensuring the sustainability and management to provide a satisfactory landing characteristics. It became apparent that with the increasing size of the planes becomes possible and appropriate to place all the major part of their weight directly in the wing. This idea was expressed in aerodynamic scheme "flying wing".The purpose of the research is to form aerodynamic look of transport aircraft "flying wing" scheme with high aspect ratio, creating aerodynamic design that provides the greatest rate of return and optimal weight range and flight duration.Objectives of the study are: analysis of scientific sources on establishing LA scheme "flying wing", development of forming methods of the aerodynamic look of transport aircraft scheme "flying wing", based on a synthesis of existing methods for assessing the flight - the technical characteristics of the aircraft, studies and analyzes of theoretical methods of aerodynamic layouts transport aircraft "flying wing" scheme to determine the aerodynamic and flight characteristics.            Were used following scientific methods to solve the research problems:             1. Method of forming the aerodynamic characteristics of the freeform aircraft shape in the parameters of similarity and generalized design parameters.             2. Statistical methods for assessing the aerodynamic and performance characteristics.             3. Numerical methods.The practical value of my work: developed method allows you to create aerodynamic layout scheme aircraft "flying wing" of the great extension that allows you to fully realize the benefits of the scheme, developed and reasonable advices on the aircraft aerodynamic look of "flying wing" scheme of high aspect ratio.

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