scholarly journals A Study on Aerodynamics and Stability Characteristics of a Bell-Shaped Span-Load Wing

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Nadhiratul Akmal Ab Razak ◽  
◽  
Mohd Fadhli Zulkafli ◽  
Keyword(s):  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Stability Characteristic ◽  
Design Team ◽  
Optimum Angle ◽  
Induced Drag ◽  
Line Theory ◽  
The Difference ◽  
Lifting Line ◽  
Lifting Line Theory

The existence of the new bell-shaped span-load wing is said to has the best lift distribution especially comparing to the elliptical wing. Bell-shaped span-load wing is designed by configuring the twist of the wing. However, the information on the aerodynamic and stability characteristics of the bell-shaped span-load wing is limited. Thus, the main purpose of the research is to evaluate the aerodynamic and stability characteristic to strengthen the claim of the capability of bell-shaped span-load wing in producing minimum induced drag. As the research is expected to be beneficial to the aviation design team, detailed information regarding the lift distribution as well as the induced drag produced is analysed at the optimum angle of attack and the results is further explained in this research. The numerical method for the analysis is done by using Lifting Line Theory (LLT) in the XFLR5 software which can analyse the wings of aircraft in terms of its aerodynamic and stability characteristic. Then, the comparison of the aerodynamic characteristics for bell-shaped span-load, elliptical span-load and tapered wing done in this research is to strengthen the appeal made stating that the bell-shaped span-load wing is the best type of wing ever existed and may replace the elliptical wing as the best wing shape with aerodynamically most efficient. The research has proven that along the wingspan, the bell-shaped span-load wing produced the lowest and minimum induced drag when being compared. At the optimum angle of attack of bell-shaped span-load wing, though the lift produced is slightly lower than the elliptical and tapered wing, the difference in the induced drag is obvious as bell-shaped span-load wing produces induced drag that is lower than 0. In other words, starting from the semi span of the wing to the wingtip, the bell-shaped span-load wing managed to be the most aerodynamically efficient wing.

Induced-drag reduction of wing–wings and wings–ground configurations

2004 ◽  
Vol 108 (1088) ◽  
pp. 523-530
Author(s):  
L. Marino
Keyword(s):  
Drag Reduction ◽  
Ground Effect ◽  
Formation Flight ◽  
Optimum Configuration ◽  
Induced Drag ◽  
Aerodynamic Model ◽  
Line Theory ◽  
Aerodynamic Parameters ◽  
Lifting Line ◽  
Lifting Line Theory

Abstract The problem of induced drag reduction during formation flight is revisited by means of a simple aerodynamic model based on lifting line theory. The optimum configuration for minimum induced drag is analysed both in and out of the ground effect and the influence of the main geometrical and aerodynamic parameters is considered. The results are discussed and compared with existing numerical and experimental data.

Optimal wing twist distribution for roll control of MAVs

2011 ◽  
Vol 115 (1172) ◽  
pp. 641-649 ◽  
Author(s):  
M. R. Ahmed ◽  
M. M. Abdelrahman ◽  
G. M. ElBayoumi ◽  
M. M. ElNomrossy
Keyword(s):  
Roll Control ◽  
Induced Drag ◽  
Load Distributions ◽  
Air Vehicle ◽  
Gradient Based ◽  
Line Theory ◽  
Symmetric Load ◽  
Lifting Line ◽  
Lifting Line Theory

Abstract The aerodynamic design optimisation of a Micro Air Vehicle (MAV) wing is performed to obtain the optimal anti-symmetric wing twist distribution for the roll control of the MAV’s wing instead of using conventional ailerons. This twist distribution should produce minimum induced drag and achieve a better roll response. The implementation of several anti-symmetric load distributions such as the half lemniscates and the Horten distributions is studied leading to an initial solution for the optimal distribution that could achieve better roll requirements. Multhopp’s method based on Prandtl’s classical lifting line theory is used for the determination of the spanwise load distribution required during the optimisation process. The optimisation process is based on the modified feasible directions gradient based optimisation algorithm implemented in the optimisation system, VisualDOC, given by Dr. Garret Vanderplaats. The proposed optimisation process is applied to the ‘BARQ’developed MAV which has successful flight in July 2009.

Comparison of Inviscid Flow Methods for Lift and Drag Calculations Over Thin-Sail Geometries

2012 ◽  
Author(s):  
Robert E. Spall ◽  
Warren F. Phillips ◽  
Brian B. Pincock
Keyword(s):  
Vortex Lattice ◽  
Lift Coefficient ◽  
Computational Cost ◽  
Inviscid Flow ◽  
Induced Drag ◽  
Line Theory ◽  
Lift And Drag ◽  
Lifting Line ◽  
Lifting Line Theory ◽  
Better Than

Solutions obtained from lifting-line, vortex-lattice, and the Euler equations are presented for a series of rigid, thin wing and sail geometries. Initial calculations were performed for an untwisted, rectangular wing. For this case, lifting line theory, vortex lattice, and Euler solutions were all in reasonable agreement. However, the lifting-line theory was the only method to predict a constant ratio of induced drag coefficient to lift coefficient squared. Similar results were found for a forward-swept, tapered wing. Additional results are presented in terms of lift and drag coefficients for an isolated mainsail, and mainsail/jib combinations with sails representative of both a standard and tall rig Catalina 27. Although experimental data is lacking, overall conclusions are that the accuracy realized from lifting-line solutions is as good as or better than that obtained from vortex-lattice solutions and inviscid CFD solutions, but at a fraction of the computational cost. The linear lifting-line results compared quite well with the nonlinear lifting-line results, with the exception of the downstream mainsail when considering jib/mainsail combinations.

Minimum Induced Drag of Non-Planar Ground Effect Wings with Small Tip Clearance

1974 ◽  
Vol 25 (1) ◽  
pp. 19-36 ◽  
Author(s):  
T Kida ◽  
Y Miyai
Keyword(s):  
Present Method ◽  
Ground Effect ◽  
Tip Clearance ◽  
Approximate Theory ◽  
Circular Arc ◽  
Induced Drag ◽  
Line Theory ◽  
Lifting Line ◽  
Wing Tip ◽  
Lifting Line Theory

SummaryThis paper treats theoretically the problem of the minimum induced drag of non-planar ground effect wings with both tips very close to the ground, within the limitations of the linearised lifting-line theory. The gap clearance between the wing tip and the ground is assumed to be very small and, using this small parameter, an approximate theory, which yields the minimum induced drag of a non-planar ground effect wing, is formulated by the method of matched asymptotic expansions. As a check on the accuracy of the method, this theory is compared with the exact theory for a semicircular wing. This shows that the present method is accurate within the small gap clearance. Moreover, the present method is applied to other wing configurations, such as semi-elliptic wings and wings with endplates, circular arc wings in a tube and circular arc wings. These computations show the theory to be very effective and it can be easily extended to various spanwise cambers.

An improved nonlinear lifting-line theory.

AIAA Journal ◽  
1973 ◽  
Vol 11 (5) ◽  
pp. 739-742 ◽  
Author(s):  
CHUAN-TAU LAN
Keyword(s):  
Line Theory ◽  
Lifting Line ◽  
Lifting Line Theory

A comprehensive comparative investigation of the Lifting Line Theory and Blade Element Momentum Theory applied to small wind turbines

2021 ◽  
pp. 1-25
Author(s):  
K.A.R. Ismail ◽  
Willian Okita
Keyword(s):  
Wind Turbines ◽  
Power Coefficient ◽  
Computational Time ◽  
Local Flow ◽  
Small Wind Turbines ◽  
Wake Effects ◽  
Line Theory ◽  
Lifting Line ◽  
Lifting Line Theory ◽  
Blade Element

Abstract Small wind turbines are adequate for electricity generation in isolated areas to promote local expansion of commercial activities and social inclusion. Blade element momentum (BEM) method is usually used for performance prediction, but generally produces overestimated predictions since the wake effects are not precisely accounted for. Lifting line theory (LLT) can represent the blade and wake effects more precisely. In the present investigation the two methods are analyzed and their predictions of the aerodynamic performance of small wind turbines are compared. Conducted simulations showed a computational time of about 149.32 s for the Gottingen GO 398 based rotor simulated by the BEM and 1007.7 s for simulation by the LLT. The analysis of the power coefficient showed a maximum difference between the predictions of the two methods of about 4.4% in the case of Gottingen GO 398 airfoil based rotor and 6.3% for simulations of the Joukowski J 0021 airfoil. In the case of the annual energy production a difference of 2.35% is found between the predictions of the two methods. The effects of the blade geometrical variants such as twist angle and chord distributions increase the numerical deviations between the two methods due to the big number of iterations in the case of LLT. The cases analyzed showed deviations between 3.4% and 4.1%. As a whole, the results showed good performance of both methods; however the lifting line theory provides more precise results and more information on the local flow over the rotor blades.

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