Asymptotic Modeling the Aerodynamic Coefficients of The NACA Airfoil

Hybrid Unmanned Aerial Vehicles (H-UAVs) are currently a very interesting field of research in the modern scientific community due to their ability to perform Vertical Take-Off and Landing (VTOL) and Conventional Take-Off and Landing (CTOL). This paper focuses on the Dual Tilt-wing UAV, a vehicle capable of performing both flight modes (VTOL and CTOL). The UAV complete dynamic model is obtained using the Newton–Euler formulation, which includes aerodynamic effects, as the drag and lift forces of the wings, which are a function of airstream generated by the rotors, the cruise speed, tilt-wing angle and angle of attack. The airstream velocity generated by the rotors is studied in a test bench. The projected area on the UAV wing that is affected by the airstream generated by the rotors is specified and 3D aerodynamic analysis is performed for this region. In addition, aerodynamic coefficients of the UAV in VTOL mode are calculated by using Computational Fluid Dynamics method (CFD) and are embedded into the nonlinear dynamic model. To validate the complete dynamic model, PD controllers are adopted for altitude and attitude control of the vehicle in VTOL mode, the controllers are simulated and implemented in the vehicle for indoor and outdoor flight experiments.

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A Parametric Study of Trailing Edge Flap Implementation on Three Different Airfoils Through an Artificial Neuronal Network

Symmetry ◽

10.3390/sym12050828 ◽

2020 ◽

Vol 12 (5) ◽

pp. 828

Author(s):

Igor Rodriguez-Eguia ◽

Iñigo Errasti ◽

Unai Fernandez-Gamiz ◽

Jesús María Blanco ◽

Ekaitz Zulueta ◽

...

Keyword(s):

Aerodynamic Coefficients ◽

Trailing Edge ◽

High Lift ◽

Trailing Edge Flaps ◽

Artificial Neural Network Ann ◽

Lift And Drag ◽

Artificial Neuronal Network ◽

Naca 0012 ◽

Drag Ratio ◽

Lift To Drag Ratio

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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Aerodynamics of inclined cylindrical bodies free-flying in a hypersonic flowfield

Experiments in Fluids ◽

10.1007/s00348-021-03269-6 ◽

2021 ◽

Vol 62 (9) ◽

Author(s):

Patrick M. Seltner ◽

Sebastian Willems ◽

Ali Gülhan ◽

Eric C. Stern ◽

Joseph M. Brock ◽

...

Keyword(s):

High Speed ◽

Degrees Of Freedom ◽

Numerical Data ◽

Static Stability ◽

Free Flight ◽

Aerodynamic Coefficients ◽

Flow Topology ◽

Motion Data ◽

Continuous Rotation ◽

German Aerospace

Abstract The influence of the flight attitude on aerodynamic coefficients and static stability of cylindrical bodies in hypersonic flows is of interest in understanding the re/entry of space debris, meteoroid fragments, launch-vehicle stages and other rotating objects. Experiments were therefore carried out in the hypersonic wind tunnel H2K at the German Aerospace Center (DLR) in Cologne. A free-flight technique was employed in H2K, which enables a continuous rotation of the cylinder without any sting interferences in a broad angular range from 0$$^{\circ }$$ ∘ to 90$$^{\circ }$$ ∘ . A high-speed stereo-tracking technique measured the model motion during free-flight and high-speed schlieren provided documentation of the flow topology. Aerodynamic coefficients were determined in careful post-processing, based on the measured 6-degrees-of-freedom (6DoF) motion data. Numerical simulations by NASA’s flow solvers Cart3D and US3D were performed for comparison purposes. As a result, the experimental and numerical data show a good agreement. The inclination of the cylinder strongly effects both the flowfield and aerodynamic loads. Experiments and simulations with concave cylinders showed marked difference in aerodynamic behavior due to the presence of a shock–shock interaction (SSI) near the middle of the model. Graphic abstract

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Longitudinal aerodynamic coefficients modeling from simulated flight data of fixed wing aircraft based on three methods

Journal of Physics Conference Series ◽

10.1088/1742-6596/1848/1/012066 ◽

2021 ◽

Vol 1848 (1) ◽

pp. 012066

Author(s):

Zhigang Wang ◽

Aijun Li ◽

Lihao Wang ◽

Shichao Ma

Keyword(s):

Aerodynamic Coefficients ◽

Flight Data

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Galloping Stability and Wind Tunnel Test of Iced Quad Bundled Conductors considering Wake Effect

Discrete Dynamics in Nature and Society ◽

10.1155/2020/8885648 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15

Author(s):

Xiaohui Liu ◽

Ming Zou ◽

Chuan Wu ◽

Mengqi Cai ◽

Guangyun Min ◽

...

Keyword(s):

Wind Tunnel ◽

Transmission Lines ◽

Degrees Of Freedom ◽

Wind Tunnel Test ◽

Aerodynamic Coefficients ◽

Wake Effect ◽

Aerodynamic Coefficient ◽

Set Up ◽

The Stability ◽

Three Degrees Of Freedom

A new quad bundle conductor galloping model considering wake effect is proposed to solve the problem of different aerodynamic coefficients of each subconductor of iced quad bundle conductor. Based on the quasistatic theory, a new 3-DOF (three degrees of freedom) galloping model of iced quad bundle conductors is established, which can accurately reflect the energy transfer and galloping of quad bundle conductor in three directions. After a series of formula derivations, the conductor stability judgment formula is obtained. In the wind tunnel test, according to the actual engineering situation, different variables are set up to accurately simulate the galloping of iced quad bundle conductor under the wind, and the aerodynamic coefficient is obtained. Finally, according to the stability judgment formula of this paper, calculate the critical wind speed of conductor galloping through programming. The dates of wind tunnel test and calculation in this paper can be used in the antigalloping design of transmission lines.

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