The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Murali Damodaran - One of the best experts on this subject based on the ideXlab platform.
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Computational aerodynamic analysis of annular wing unmanned aerial vehicles
53rd AIAA Aerospace Sciences Meeting, 2015Co-Authors: Akshay A. Kanoria, Kartik C. Panchal, Murali DamodaranAbstract:Annular or Ring wing concept is a form of closed non-planar wing. The benefits of nonplanar wing aerodynamics are well known and have been elucidated theoretically and experimentally. The widespread use of non-planar wings during the early years of humanpowered flight had more to do with structural expediency than augmented aerodynamic efficiency. Non-planarity for a confined wing span may improve wing efficiency by capturing larger volume of air to generate lift impulse. In this study, the aerodynamic characteristics of an annular wing composed of symmetric airfoil section NACA 0012 is investigated for various aspect ratios ranging from 0.5 to 2. The computational modeling showed higher lift coefficient for aspect ratio of 2 and the resulting L/D ratio is observed to be best for this aspect ratio. To study effect of asymmetry, a cambered Clark-Y airfoil is considered as a wing section for the annular wing. The Clark-Y annular wing showed better aerodynamic characteristics with a Stall Angle higher than that of the NACA 0012 annular wing and attaining better L/D ratio at lower Angle of attack. Further, a brief comparison between annular wing and conventional wing shows that a higher lift coefficient is observed for planar wing but annular wing admitted a higher Stall Angle. Computational results are compared with available theoretical results and experimental data. Owing to the benefits offered by cambered airfoil, an annular wing with Clark-Y airfoil is considered for an annular wing UAV design configuration with a V-tail empennage adopted for the UAV configuration Nomenclature AR = Aspect ratio CL = Lift Coefficient CD = Drag Coefficient CP = Pressure Coefficient L/D = Lift to Drag ratio acw = Aerodynamic Centre of Annular Wing act = Aerodynamic center of V-tail Xg = Distance between Aerodynamic center of wing and center of gravity of UAV Xt = Distance between Aerodynamic centers of wing and of horizontal tail Xn = Distance between Aerodynamic center and neutral point Vt = Volume Tail ratio, St = Tail Surface area Sw = Wing surface area Cw = Wing chord length * Graduate Student and DEITY Junior Research Fellow, Email: a.kanoria@iitgn.ac.in † Project Engineer, Email: kartikpanchal@iitgn.ac.in ‡ Professor, Associate Fellow AIAA, Email: murali@iitgn.ac.in
Yang Liu - One of the best experts on this subject based on the ideXlab platform.
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Numerical study of flows past airfoils with wavy surfaces
Journal of Fluids and Structures, 2013Co-Authors: Y. F. Lin, Lin Zou, Kwok Cheung Andrew Lam, Yang LiuAbstract:Abstract The paper presents three-dimensional numerical studies on the aerodynamic characteristics of two different modified NACA0012 airfoils with different wavy surfaces using the large eddy simulations. Two types of wavy airfoils are investigated with wavy airfoil-A having a sinusoidal waviness on upper and lower surfaces with a constant chord length, while wavy airfoil-B having sinusoidal variation in both of the leading and trailing edges as well as on the upper and lower surfaces along the spanwise direction. The force characteristics and the flow structures are captured and compared with a corresponding standard NACA0012 airfoil with a Reynolds number of Re=1.6×10 5 . The flow structures and surface pressure distributions on wavy airfoils were found to be significantly different from those on a conventional NACA0012 airfoil. For Angles of attack less than the baseline Stall Angle of a NACA0012 airfoil, a slight decrease of lift coefficient was observed for both types of wavy airfoils, while the lift coefficient for the wavy airfoil-B increases up to 20% greater than that of a NACA0012 airfoil when the Angle of attack is larger than the baseline Stall Angle of 13°. The flow over the leading edge of wavy airfoil-B remained attached at post Stall Angles of attack. In general, the wavy airfoil-A just exhibits a suppression the airfoil’s fluctuation force, while the wavy airfoil-B demonstrates an advantageous aerodynamic effect on the control of loss of lift in the post Stall regime of a conventional NACA0012 airfoil.
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Numerical Investigation of Flow past a Wavy Airfoil
Applied Mechanics and Materials, 2011Co-Authors: K. Lam, Y. F. Lin, Yang Liu, Lin ZouAbstract:The effect of the wavy surface on the aerodynamic characteristics of an airfoil is studied using the large eddy simulations. A more gentle lift characteristic is obtained during Stall. For Angles of attack less than the baseline Stall Angle of a NACA0012 airfoil, a lift coefficient reduction was observed for the wavy airfoils, while the lift coefficient increases up to 23% greater than that of a NACA0012 airfoil when the Angle of attack is larger than the baseline Stall Angle of the NACA0012 airfoil.
Akshay A. Kanoria - One of the best experts on this subject based on the ideXlab platform.
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Computational aerodynamic analysis of annular wing unmanned aerial vehicles
53rd AIAA Aerospace Sciences Meeting, 2015Co-Authors: Akshay A. Kanoria, Kartik C. Panchal, Murali DamodaranAbstract:Annular or Ring wing concept is a form of closed non-planar wing. The benefits of nonplanar wing aerodynamics are well known and have been elucidated theoretically and experimentally. The widespread use of non-planar wings during the early years of humanpowered flight had more to do with structural expediency than augmented aerodynamic efficiency. Non-planarity for a confined wing span may improve wing efficiency by capturing larger volume of air to generate lift impulse. In this study, the aerodynamic characteristics of an annular wing composed of symmetric airfoil section NACA 0012 is investigated for various aspect ratios ranging from 0.5 to 2. The computational modeling showed higher lift coefficient for aspect ratio of 2 and the resulting L/D ratio is observed to be best for this aspect ratio. To study effect of asymmetry, a cambered Clark-Y airfoil is considered as a wing section for the annular wing. The Clark-Y annular wing showed better aerodynamic characteristics with a Stall Angle higher than that of the NACA 0012 annular wing and attaining better L/D ratio at lower Angle of attack. Further, a brief comparison between annular wing and conventional wing shows that a higher lift coefficient is observed for planar wing but annular wing admitted a higher Stall Angle. Computational results are compared with available theoretical results and experimental data. Owing to the benefits offered by cambered airfoil, an annular wing with Clark-Y airfoil is considered for an annular wing UAV design configuration with a V-tail empennage adopted for the UAV configuration Nomenclature AR = Aspect ratio CL = Lift Coefficient CD = Drag Coefficient CP = Pressure Coefficient L/D = Lift to Drag ratio acw = Aerodynamic Centre of Annular Wing act = Aerodynamic center of V-tail Xg = Distance between Aerodynamic center of wing and center of gravity of UAV Xt = Distance between Aerodynamic centers of wing and of horizontal tail Xn = Distance between Aerodynamic center and neutral point Vt = Volume Tail ratio, St = Tail Surface area Sw = Wing surface area Cw = Wing chord length * Graduate Student and DEITY Junior Research Fellow, Email: a.kanoria@iitgn.ac.in † Project Engineer, Email: kartikpanchal@iitgn.ac.in ‡ Professor, Associate Fellow AIAA, Email: murali@iitgn.ac.in
Haecheon Choi - One of the best experts on this subject based on the ideXlab platform.
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Flow structure modifications by leading-edge tubercles on a 3D wing.
Bioinspiration & biomimetics, 2018Co-Authors: Heesu Kim, Jooha Kim, Haecheon ChoiAbstract:Leading-edge tubercles on a humpback whale flipper are known to enhance its hydrodynamic performance at post-Stall Angles of attack (Miklosovic et al 2004 Phys. Fluids 16 39-42). We investigate vortical structures above a three-dimensional wing with tubercles using surface-oil-flow visualization and particle image velocimetry measurement. Two wing models with and without tubercles, previously studied by Miklosovic et al (2004 Phys. Fluids 16 39-42), are considered at the Reynolds number of 180 000 based on the free-stream velocity and mean chord length. At this Reynolds number, tubercles delay the Stall Angle by 7° and increase the maximum lift coefficient by about 22%. At a low Angle of attack, flow separation first occurs near the tip region for both wing models. While flow separation rapidly progresses inboard (toward the wing root) for the model without tubercles with increasing Angle of attack, tubercles produce two types of vortical motions and block the inboard progression of flow separation, resulting in delayed Stall from α = 8° to 15°. One of these two vortical structures is pairs of counter-rotating streamwise vortices evolving from hemi-spherical separation bubbles near the leading-edge troughs at pre-, near-, and post-Stall Angles of attack, and the other is asymmetric pairs of streamwise vortices evolving from separated flow regions after the mid-chord region at near-Stall Angle of attack. At a post-Stall Angle of attack (α = 16°), strong clockwise and counter-clockwise streamwise vortices are generated from foci at the root and tip near the trailing edge, respectively, and delay flow separation in the mid-span, resulting in a higher lift coefficient than that without tubercles.
Y. F. Lin - One of the best experts on this subject based on the ideXlab platform.
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Numerical study of flows past airfoils with wavy surfaces
Journal of Fluids and Structures, 2013Co-Authors: Y. F. Lin, Lin Zou, Kwok Cheung Andrew Lam, Yang LiuAbstract:Abstract The paper presents three-dimensional numerical studies on the aerodynamic characteristics of two different modified NACA0012 airfoils with different wavy surfaces using the large eddy simulations. Two types of wavy airfoils are investigated with wavy airfoil-A having a sinusoidal waviness on upper and lower surfaces with a constant chord length, while wavy airfoil-B having sinusoidal variation in both of the leading and trailing edges as well as on the upper and lower surfaces along the spanwise direction. The force characteristics and the flow structures are captured and compared with a corresponding standard NACA0012 airfoil with a Reynolds number of Re=1.6×10 5 . The flow structures and surface pressure distributions on wavy airfoils were found to be significantly different from those on a conventional NACA0012 airfoil. For Angles of attack less than the baseline Stall Angle of a NACA0012 airfoil, a slight decrease of lift coefficient was observed for both types of wavy airfoils, while the lift coefficient for the wavy airfoil-B increases up to 20% greater than that of a NACA0012 airfoil when the Angle of attack is larger than the baseline Stall Angle of 13°. The flow over the leading edge of wavy airfoil-B remained attached at post Stall Angles of attack. In general, the wavy airfoil-A just exhibits a suppression the airfoil’s fluctuation force, while the wavy airfoil-B demonstrates an advantageous aerodynamic effect on the control of loss of lift in the post Stall regime of a conventional NACA0012 airfoil.
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Numerical Investigation of Flow past a Wavy Airfoil
Applied Mechanics and Materials, 2011Co-Authors: K. Lam, Y. F. Lin, Yang Liu, Lin ZouAbstract:The effect of the wavy surface on the aerodynamic characteristics of an airfoil is studied using the large eddy simulations. A more gentle lift characteristic is obtained during Stall. For Angles of attack less than the baseline Stall Angle of a NACA0012 airfoil, a lift coefficient reduction was observed for the wavy airfoils, while the lift coefficient increases up to 23% greater than that of a NACA0012 airfoil when the Angle of attack is larger than the baseline Stall Angle of the NACA0012 airfoil.