scholarly journals 2D numerical investigations derived from a 3D dragonfly wing captured with a high-resolution micro-CT

2021 ◽  
pp. 1-7
Author(s):  
Vera Stelzer ◽  
Lars Krenkel
Keyword(s):  
High Resolution ◽  
3D Model ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Micro Ct ◽  
Numerical Investigations ◽  
Dragonfly Wing ◽  
Recirculation Zones ◽  
Drag Ratio ◽  
Lift To Drag Ratio

BACKGROUND: Due to their corrugated profile, dragonfly wings have special aerodynamic characteristics during flying and gliding. OBJECTIVE: The aim of this study was to create a realistic 3D model of a dragonfly wing captured with a high-resolution micro-CT. To represent geometry changes in span and chord length and their aerodynamic effects, numerical investigations are carried out at different wing positions. METHODS: The forewing of a Camacinia gigantea was captured using a micro-CT. After the wing was adapted an error-free 3D model resulted. The wing was cut every 5 mm and 2D numerical analyses were conducted in Fluent® 2020 R2 (ANSYS, Inc., Canonsburg, PA, USA). RESULTS: The highest lift coefficient, as well as the highest lift-to-drag ratio, resulted at 0 mm and an angle of attack (AOA) of 5∘. At AOAs of 10∘ or 15∘, the flow around the wing stalled and a Kármán vortex street behind the wing becomes visible. CONCLUSIONS: The velocity is higher on the upper side of the wing compared to the lower side. The pressure acts vice versa. Due to the recirculation zones that are formed in valleys of the corrugation pattern the wing resembles the form of an airfoil.

scholarly journals Aerodynamic and Vibration Characteristics of the Micro-Octocopter at Low Reynolds Number

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xiaohua Zou ◽  
Mingsheng Ling ◽  
Wenzheng Zhai
Keyword(s):  
Reynolds Number ◽  
Load Capacity ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Vibration Characteristics ◽  
Low Reynolds ◽  
Vibration Performance ◽  
Drag Ratio ◽  
Lift To Drag Ratio

With the development of flight technology, the need for stable aerodynamic and vibration performance of the aircraft in the civil and military fields has gradually increased. In this case, the requirements for aerodynamic and vibration characteristics of the aircraft have also been strengthened. The existing four-rotor aircraft carries limited airborne equipment and payload, while the current eight-rotor aircraft adopts a plane layout. The size of the propeller is generally fixed, including the load capacity. The upper and lower tower layout analyzed in this paper can effectively solve the problems of insufficient four-axis load and unstable aerodynamic and vibration performance of the existing eight-axis aircraft. This paper takes the miniature octorotor as the research object and studies the aerodynamic characteristics of the miniature octorotor at different low Reynolds numbers, different air pressures and thicknesses, and the lift coefficient and lift-to-drag ratio, as well as the vibration under different elastic moduli and air pressure characteristics. The research algorithm adopted in this paper is the numerical method of fluid-solid cohesion and the control equation of flow field analysis. The research results show that, with the increase in the Reynolds number within a certain range, the aerodynamic characteristics of the miniature octorotor gradually become better. When the elastic modulus is 2.5 E, the aircraft’s specific performance is that the lift increases, the critical angle of attack increases, the drag decreases, the lift-to-drag ratio increases significantly, and the angle of attack decreases. However, the transition position of the flow around the airfoil surface is getting closer to the leading edge, and its state is more likely to transition from laminar flow to turbulent flow. When the unidirectional carbon fiber-reinforced thickness is 0.2 mm and the thin arc-shaped airfoil with the convex structure has a uniform thickness of 2.5% and a uniform curvature of 4.5%, the aerodynamic and vibration characteristics of the octorotor aircraft are most beneficial to flight.

Aerodynamic characteristics of breathing blunt nose configuration at hypersonic speeds

2016 ◽  
Vol 231 (5) ◽  
pp. 840-858 ◽  
Author(s):  
Yasumasa Watanabe ◽  
Kojiro Suzuki ◽  
Ethirajan Rathakrishnan
Keyword(s):  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
The Body ◽  
Positive Pressure ◽  
Stagnation Region ◽  
Total Drag ◽  
Hypersonic Speeds ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Blunt Nose

Breathing blunt nose technique is one of the promising methods for reducing the drag of blunt-nosed body at hypersonic speeds. The air, traversed by the bow shock positioned ahead of the nose, at the stagnation region is allowed to enter through a hole at the blunt-nose and ejected at the rear part (base region) of the body. This manipulation reduces the positive pressure over the stagnation regions of the nose and increases the pressure at the base, resulting in reduced suction at the base. The simultaneous manifestation of reducing the compression at the nose and suction at the base regions results in reduction of the total drag. The drag reduction caused by the breathing blunt nose technique has been measured in a Mach 7 tunnel. Also, the drag and flow field around the blunt-nosed body, with and without breathing hole, has been computed. The aerodynamic characteristics of the breathing blunt nose model obtained experimentally are compared with the CFD results. It is found that the breathing results in 5% reduction in drag. The lift coefficient also comes down for the model with breathing nose. But the lift-to-drag ratio is found to be the same for both the cases; the blunt-nosed body with and without nose-hole.

Based on Imitation Seagull Airfoil UVA Wing Numerical Simulation

2012 ◽  
Vol 271-272 ◽  
pp. 791-796
Author(s):  
Xin Hua ◽  
Wei Shao ◽  
Chun Hua Zhang ◽  
Zhi Qiang Zhang
Keyword(s):  
Numerical Simulation ◽  
High Performance ◽  
Lift Coefficient ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Wing Scale ◽  
Fluent Software ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Straight Wing

Wing aircraft is one of the major components to generate lift, in today's energy shortage, design the high lift-to-drag ratio wing is the goal pursued by, The author in the exploration of bionic airfoil aerodynamic characteristics on the basis of, which will be applied to straight wing design so as to improve the aerodynamic performance of aircraft.Our research mainly includes two aspects: first, the use of imitation seagull airfoil and NACA4412 airfoil are designed into the straight wing. The use of FLUENT software in Re=300000condition carries on the numerical simulation results show that the ratio of gull wing airfoil than NACA4412 lift coefficient increased by 13%, while the lift to drag ratio,is improved by 46.83%. Then, using the similarity principle, the wing scale, was tested in a wind tunnel test, the results obtained with the simulation are consistent. Airfoil design for the design of high performance wing opened a new way.

scholarly journals Lift and Drag Coefficient Map of NACA4415 Airfoil

2021 ◽  
Vol 2076 (1) ◽  
pp. 012066
Author(s):  
Rui Yin ◽  
Jing Huang ◽  
Zhi-Yuan He
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Optimal Angle ◽  
Fluent Software ◽  
Lift And Drag ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Abstract The NACA4415 airfoil was numerically simulated with the help of the Fluent software to analyze its aerodynamic characteristics. Results are acquired as follows: The calculation accuracy of Fluent software is much higher than that of XFOIL software; the calculation result of SST k-ω(sstkw) turbulence model is closest to the experimental value; within a certain range, the larger the Reynolds number is, the larger the lift coefficient and lift-to-drag ratio of the airfoil will be, and the smaller the drag coefficient will be; when the angle of attack is less than the optimal angle of attack, the Reynolds number has less influence on the lift-to-drag coefficient and the lift-to-drag ratio; as the Reynolds number increases, the optimal angle of attack increases slightly, and the applicable angle of attack range for high lift-to-drag ratios becomes smaller.

scholarly journals Effects of Pitching Motion Elements on Aerodynamic Characteristics of Airfoil

2021 ◽  
Vol 2076 (1) ◽  
pp. 012078
Author(s):  
Rui Yin ◽  
Jing Huang ◽  
Zhi-Yuan He
Keyword(s):  
Drag Coefficient ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Initial Angle ◽  
Pitching Motion ◽  
The Difference ◽  
Lift And Drag ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Abstract The aerodynamic characteristics of NACA4412 airfoil with different pitching motion elements were compared and analyzed based on CFD in this research. The results are acquired as follows: the difference between the lift and drag coefficients of the airfoil during pitch up and pitch down motions becomes larger with the increase of the pitching amplitude or initial angle of attack; as the pitching amplitude increases, the lift coefficient grows slightly greater and the drag coefficient grows much greater; as the initial angle of attack increases, the lift coefficient grows much greater and the drag coefficient grows slightly; the smaller the attenuation frequency is, the larger the lift-to-drag ratio of the airfoil will be.

scholarly journals Experimental Determination of the Impact of Floats on the Aerodynamic Characteristics of an OSA Model in Symmetric Flow

2021 ◽  
Vol 12 (1) ◽  
pp. 41-58
Author(s):  
Michał FRANT ◽  
Stanisław WRZESIEŃ ◽  
Maciej MAJCHER
Keyword(s):  
Drag Coefficient ◽  
Aerodynamic Drag ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Symmetric Flow ◽  
Aerodynamic Drag Coefficient ◽  
The Impact ◽  
Drag Ratio ◽  
Lift To Drag Ratio

This paper presents the results of experimental determination of the impact of floats on the aerodynamic characteristics of an OSA model in symmetric flow. The studies have been performed in the low-speed wind tunnel at the Military University of Technology (MUT, Warsaw, Poland). The aircraft model was examined at the dynamic pressure q = 500 Pa in the following angle of attack range = -2828. The investigations have been performed for an aircraft model under plain configuration with floats and without floats. The influence of elevator and flap inclination on the aerodynamic characteristics of the model has also been analysed. The obtained values of aerodynamic drag coefficient, lift coefficient, pitching moment coefficient and lift-to-drag ratio have been presented in the form of tables and graphs. The studies performed demonstrated that the use of floats causes the increase of aerodynamic drag coefficient CD, maximum lift coefficient CLmax as well as critical angle of attack cr. The decrease of lift-to-drag ratio has also been observed. Its value in the case of the model with floats was up to 20% lower than in the model without floats. The studies also showed that the model equipped with floats had a lower longitudinal static stability margin than the model without floats.

scholarly journals Aerodynamic characteristics of a cranked planform blended wing-body aircraft with 400 sweep angle

2018 ◽  
Vol 7 (4.13) ◽  
pp. 37
Author(s):  
A M Ahmad ◽  
R E M Nasir ◽  
Z A A Latif ◽  
W Kuntjoro ◽  
W Wisnoe ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Entire Body ◽  
Sweep Angle ◽  
Tunnel Model ◽  
Body Design ◽  
Blended Wing Body ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Baseline 7 Blended Wing-Body design is introduced to study the behaviour of the control surfaces, given four elevons without vertical stabilizer and wingtip. The objective of the paper is to obtain an aerodynamic characteristic of a cranked planform blended wing-body aircraft. The airfoil used for the entire body is NACA 2412, which is selected for ease of fabrication process. The wingspan of the model is 1.4 m with 0.2 m thickness. The sweep angle of the model is fixed to 400. The wingspan area is calculated at 0.405 m2. The experiment is conducted at UTM-LST Wind Tunnel, AEROLAB, Skudai, Johor with test wind speed of 15 m/s. The maximum lift-to-drag ratio for the model is found to be around 21.9, which is better than many conventional aircraft. Nonetheless, the parabolic regression made to the drag versus lift plot only yields maximum lift-to-drag ratio of 10.0. The value of drag coefficient at zero lift is 0.012 while the maximum lift coefficient found is at 0.65 at 150 angle of attack. The lift-to-drag ratio improves 38.3% from 15.9 in the previously-published design. The neutral point is found to be located at 30.6% of the mean geometric chord in front of the wind tunnel model reference center or about 0.398 m from the nose of the 0.63 m long aircraft model or at 63.1% of aircraft length from the nose.  

scholarly journals Influences of distributed propulsion system parameters on aerodynamic characteristics of a BLI-BWB UAV

2021 ◽  
Vol 39 (1) ◽  
pp. 17-26
Author(s):  
Yang Zhang ◽  
Zhou Zhou ◽  
Kelei Wang ◽  
Zhongyun Fan
Keyword(s):  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Propulsion System ◽  
Navier Stokes ◽  
System Parameters ◽  
Ducted Fan ◽  
Distributed Propulsion ◽  
Air Flow Velocity ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Focusing on the aerodynamic characteristics of the blended wing body (BWB) aircraft with boundary layer ingestion(BLI) distributed propulsion system; the influences of propulsion system parameters under the condition of cruise and takeoff are studied. Firstly, based on the momentum source method (MSM), the NASA ducted propeller model is simulated, which verifies the reliability of the numerical method in this paper. Then, by using the method of structural grid and S-A turbulence model to solve the Reynolds averaged Navier-Stokes (RANS) equation, the aerodynamic characteristics of the BLI UAV model with D80 ducted fan in cruise state are numerically calculated. It is proved that the advantage of the BLI distributed propulsion system is superior in increasing lift. And the aerodynamic characteristics of the BLI UAV with different propulsion system parameters are compared. At last, the aerodynamic effect of ducted fan thrust on the BLI UAV is carried out. The results show that, due to the suction function of the BLI distributed propulsion system, the air flow velocity near the BWB fuselage is effectively accelerated, and the flow along the spanwise is restrained, which improves the lift coefficient about 16% and lift-to-drag ratio about 10%. Under the condition of equal thrust, the D80 ducted fan brings larger load of the propeller, which makes the static pressure at the inlet and outlet smaller. Compared with D150 ducted fan, the lift-to-drag ratio is increased by 15%. When aircraft takes off, increasing the thrust of the ducted fan can reduce the possibility of flow separation on the upper surface of the fuselage, which is conducive to the safety.

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

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.

Aerodynamic study of single corrugated variable-camber morphing aerofoil concept

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.

Sign in / Sign up

Export Citation Format

Share Document