Augmentation of Lift-to-Drag Ratio for a Wing Using Thermal Forcing

Trailing edge flaps (TEFs) are high-lift devices that generate changes in the lift and drag coefficients of an airfoil. A large number of 2D simulations are performed in this study, in order to measure these changes in aerodynamic coefficients and to analyze them for a given Reynolds number. Three different airfoils, namely NACA 0012, NACA 64(3)-618, and S810, are studied in relation to three combinations of the following parameters: angle of attack, flap angle (deflection), and flaplength. Results are in concordance with the aerodynamic results expected when studying a TEF on an airfoil, showing the effect exerted by the three parameters on both aerodynamic coefficients lift and drag. Depending on whether the airfoil flap is deployed on either the pressure zone or the suction zone, the lift-to-drag ratio, CL/CD, will increase or decrease, respectively. Besides, the use of a larger flap length will increase the higher values and decrease the lower values of the CL/CD ratio. In addition, an artificial neural network (ANN) based prediction model for aerodynamic forces was built through the results obtained from the research.

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Fluid–structure interaction simulation on flight performance of a dragonfly wing under different pterostigma weights

Journal of Mechanics ◽

10.1093/jom/ufaa013 ◽

2021 ◽

Vol 37 ◽

pp. 216-229

Author(s):

Yung Jeh Chu ◽

Poo Balan Ganesan ◽

Mohamad Azlin Ali

Keyword(s):

Optimization Design ◽

Fluid Structure Interaction ◽

Spatial Location ◽

Fluid Structure ◽

Structure Interaction ◽

Dragonfly Wing ◽

Interaction Simulation ◽

Wing Performance ◽

Drag Ratio ◽

Lift To Drag Ratio

Abstract The dragonfly wings provide insights for designing an efficient biomimetic micro air vehicle (BMAV). In this regard, this study focuses on investigating the effect of the pterostigma weight loading and its spatial location on the forewings of dragonfly by using the fluid–structure interaction simulation. This study also investigates the effect of change in the wing elasticity and density on the wing performance. The forewing, which mimics the real dragonfly wing, is flat with a 47.5 mm span and a 0.4 mm thickness. The wing was set to cruise at 3 m/s with a constant flapping motion at a frequency of 25 Hz. This study shows that a small increase of pterostigma loading (11% of wing weight) at the tip of the wing significantly improves the lift to drag ratio, CL/CD, which has 129.16% increment in comparison with no loading. The lift to drag ratio depends on the pterostigma location, pterostigma loading, elastic modulus and density. The results of this study can be used as a reference in future BMAV wing optimization design.

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Aerodynamic study of single corrugated variable-camber morphing aerofoil concept

The Aeronautical Journal ◽

10.1017/aer.2021.71 ◽

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.

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Hydrodynamic Evaluation of a Generic Sail Used in an Innovative Prawn-Trawl Otter Board

Volume 6: Ocean Space Utilization ◽

10.1115/omae2015-41335 ◽

2015 ◽

Cited By ~ 2

Author(s):

Cheslav Balash ◽

David Sterling ◽

Matt Broadhurst ◽

Arno Dubois ◽

Morgan Behrel

Keyword(s):

Degrees Of Freedom ◽

Design Feature ◽

Hydrodynamic Characteristics ◽

Flat Plates ◽

Successful Operation ◽

Six Degrees Of Freedom ◽

Recent Innovation ◽

Hydrodynamic Evaluation ◽

Drag Ratio ◽

Lift To Drag Ratio

In prawn-trawling operations, otter boards provide the horizontal force required to maintain net openings, and are typically low aspect ratio (∼0.5) flat plates operating on the seabed at high angles of attack (AOA; 35–40°). Such characteristics cause otter boards to account for up to 30% of the total trawling resistance, including that from the vessel. A recent innovation is the batwing otter board, which is designed to spread trawls with substantially less towing resistance and benthic impacts. A key design feature is the use of a sail, instead of a flat plate, as the hydrodynamic foil. The superior drag and benthic performance of the batwing is achieved by (i) successful operation at an AOA of ∼20° and (ii) having the heavy sea floor contact shoe in line with the direction of tow. This study investigated the hydrodynamic characteristics of a generic sail by varying its twist and camber, to identify optimal settings for maximum spreading efficiency and stability. Loads in six degrees of freedom were measured at AOAs between 0 and 40° in a flume tank at a constant flow velocity, and with five combinations of twist and camber. The results showed that for the studied sail, the design AOA (20°) provides a suitable compromise between greater efficiency (occurring at lower AOAs) and greater effectiveness (occurring at higher AOAs). At optimum settings (20°, medium camber and twist), a lift-to-drag ratio >3 was achieved, which is ∼3 times more than that of contemporary prawn-trawling otter boards. Such a result implies relative drag reductions of 10–20% for trawling systems, depending on the rig configuration.

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Review of space vehicle control and guidance methods at atmosphere reentry

Keldysh Institute Preprints ◽

10.20948/prepr-2021-5 ◽

2021 ◽

pp. 1-20

Author(s):

Alexander Sergeevich Samotokhin

Keyword(s):

Space Vehicle ◽

Vehicle Control ◽

Control Methods ◽

The Moon ◽

Reentry Vehicles ◽

Drag Ratio ◽

Lift To Drag Ratio

Review of control methods for statically stable reentry vehicles with low lift-to-drag ratio at returning from the Moon is presented. We are considering algorithms that have been used in Soviet and American Moon programs, as well as advanced algorithms that now are developed. General trends of advanced domestic and foreign methods are determined.

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