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Journal articles on the topic 'Wing dihedral'
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1
Traub, L. W., R. Waghela, and K. A. Bordignon. "Characterisation of a highly staggered spanwise cambered biplane." Aeronautical Journal 119, no. 1212 (February 2015): 203–28. http://dx.doi.org/10.1017/s0001924000010344.
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AbstractAn investigation is presented to elucidate the performance of a staggered, spanwise cambered biplane. The spanwise camber yielded wings forming a ‘∧’ or ‘∨’ when viewed streamwise. The configuration is examined in terms of its aerodynamic and stability characteristics. The feasibility of negating the requirement for a conventional empennage is explored. Geometric variation encompassed front and back wing anhedral/dihedral angles yielding 49 combinations. Evaluation of the geometry was accomplished using both wind tunnel testing and numerical simulation. The results indicated that front wing dihedral in conjunction with aft wing anhedral was most beneficial, such that the benefit of wake spacing was maximised. Aerodynamic benefit was indicated compared to a conventional empennage geometry. The greatest disparity in behaviour of the fore and aft wing anhedral/dihedral distribution was in the high lift regime, where the nature of the stall varied. Simulations to establish the viability of the geometry in terms of controllability were also conducted and indicated that the configuration is viable.
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Phillips, W. F. "Analytical Solution for Wing Dihedral Effect." Journal of Aircraft 39, no. 3 (May 2002): 514–16. http://dx.doi.org/10.2514/2.2960.
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Streit, T., and C. Hoffrogge. "DLR transonic inverse design code, extensions and modifications to increase versatility and robustness." Aeronautical Journal 121, no. 1245 (October 11, 2017): 1733–57. http://dx.doi.org/10.1017/aer.2017.101.
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ABSTRACTThe DLR inverse design code computes the wing geometry for a prescribed target pressure distribution. It is based on the numerical solution of the integral inverse transonic small perturbation (TSP) equations. In this work, several extensions and modifications of the inverse design code are described. Results are validated with corresponding redesign test cases. The first modification concerns applications for high transonic Mach numbers or cases with strong shocks. The introduced modifications enable converged design solutions for cases where the original method failed. The second modification is the extension of the code to general non-planar wings. Previously, the design code was restricted to non-planar wing designs with small dihedral or to nacelle design. A third modification concerns aerofoil/wings designed for wind-tunnel design. In order to design a swept wing between two wind-tunnel walls, the solution method was extended to two symmetry planes. The introduced extensions and modifications have increased the robustness and range of applicability of the inverse design code.
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G., Prasad, Ramesh M., and Rajasekar K. "Numerical Investigation on Effect of Multiple Winglets for Wind Turbine Applications." International Journal of Engineering & Technology 7, no. 4.5 (September 22, 2018): 450. http://dx.doi.org/10.14419/ijet.v7i4.5.20204.
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The present article is an effort to examine the potential of multiple winglets to reduce the induced drag of the aerodynamic surface. The advantages of using multiple winglets include reduction of induced drag, increased L/D and improved performance of the Wind turbine. Computational Fluid Dynamics is utilized as to approach the effects of multiple winglets with NACA 24012 airfoil section for untwisted, rectangular wing. The testing of configurations is done at Reynolds number 290,000. FLUENT solver incorporated in ANSYS used for the numerical investigation of the steady flow over the wing. A substantial improvement in lift curve slope occurs with dihedral spread of the winglets. The dihedral spread also distributes the tip vortices.
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Wang, Zhi Gang, and Zhen Ning Zhang. "Modeling and Simulation of Unsteady Aerodynamics on a Morphing Wing." Applied Mechanics and Materials 427-429 (September 2013): 77–80. http://dx.doi.org/10.4028/www.scientific.net/amm.427-429.77.
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Modeling and simulation method of unsteady aerodynamics on morphing wings were investigated. The Unsteady Vortex Lattice Method is employed to model the unsteady aerodynamics of 3-D potential flow field surrounding the wing. An UVLM computer code was then developed and validated for numerical simulation. A morphing wing which changes its dihedral angle with constant angular velocity was investigated by the code, and the lift, induced drag, and pitching moment coefficients time histories were obtained. The results show that the UVLM code is an effective tool for simulations of unsteady aerodynamics on morphing wings.
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NAKAGAWA, Toru, Satoshi KIKUCHI, Shigeki IMAO, and Yasuaki KOZATO. "207 Effect of Dihedral Angle on Wing in Ground Effect." Proceedings of Conference of Tokai Branch 2011.60 (2011): _207–1_—_207–2_. http://dx.doi.org/10.1299/jsmetokai.2011.60._207-1_.
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Bourdin, P., A. Gatto, and M. I. Friswell. "Performing co-ordinated turns with articulated wing-tips as multi-axis control effectors." Aeronautical Journal 114, no. 1151 (January 2010): 35–47. http://dx.doi.org/10.1017/s0001924000003511.
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Abstract This paper investigates a novel method for the control of aircraft. The concept consists of articulated split wing-tips, independently actuated and mounted on a baseline flying wing. The general philosophy behind the concept was that adequate control of a flying wing about its three axes could be obtained through local modifications of the dihedral angle at the wing-tips, thus providing an alternative to conventional control effectors such as elevons and drag rudders. Preliminary computations with a vortex lattice model and subsequent wind tunnel tests and Navier-Stokes computations demonstrate the viability of the concept for co-ordinated turns, with individual and/or combined wing-tip deflections producing multi-axis, coupled control moments. The multi-axis nature of the generated moments tends to over-actuate the flight control system, leading to some redundancy, which could be exploited to optimise secondary objective functions such as drag or bending moment.
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Wang, Caidong, Chen Wang, Yu Ning, Lumin Chen, and Xinjie Wang. "Design and Mechanical Analysis of Bionic Foldable Beetle Wings." Applied Bionics and Biomechanics 2018 (August 9, 2018): 1–10. http://dx.doi.org/10.1155/2018/1308465.
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In order to improve the flight performance of collapsible aircrafts, a novel mechanism of bionic foldable wings of beetle is designed based on the four-plate mechanism theory. The folding and unfolding movements of the bionic foldable wings are driven by motor and torsion hinges. Based on the D-H method, a kinematic model of wings is established to analyze the dihedral angle of adjacent plates. The folding ratio of an area in different plate creasing angles has been derived and calculated. Utilizing the kinematic and static models produced, as well as considering the folding ratio and output motor torque, the optimal physical parameters of folding wings are obtained. Dynamic models of rigid and flexible wings were established using ADAMS, and a motion simulation was performed. The relationship between dihedral angle and torque during the folding process of both rigid and flexible wings was obtained. The results provide a better understanding of the folding mechanism through the formulation of rigid-flexible wing analysis, as well as demonstrating a novel design of insect-mimicking artificial wings for small aerial vehicles.
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Est, Brian E., and H. F. Nelson. "Fin dihedral effects on wing-body carryover for supersonic noncircular missiles." Journal of Spacecraft and Rockets 32, no. 3 (May 1995): 433–39. http://dx.doi.org/10.2514/3.26633.
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Afonso, F., G. Leal, J. Vale, É. Oliveira, F. Lau, and A. Suleman. "The effect of stiffness and geometric parameters on the nonlinear aeroelastic performance of high aspect ratio wings." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 231, no. 10 (November 25, 2016): 1824–50. http://dx.doi.org/10.1177/0954410016675893.
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The increase in wing aspect ratio is gaining interest among aircraft designers in conventional and joined-wing configurations due to the higher lift-to-drag ratios and longer ranges. However, current transport aircraft have relatively small aspect ratios due their increased structural stiffness. The more flexible the wing is more prone to higher deflections under the same operating condition, which may result in a geometrical nonlinear behavior. This nonlinear effect can lead to the occurrence of aeroelastic instabilities such as flutter sooner than in an equivalent stiffer wing. In this work, the effect of important stiffness (inertia ratio and torsional stiffness) and geometric (sweep and dihedral angles) design parameters on aeroelastic performance of a rectangular high aspect ratio wing model is assessed. The torsional stiffness was observed to present a higher influence on the flutter speed than the inertia ratio. Here, the decrease of the inertia ratio and the increase of the torsional stiffness results in higher flutter and divergence speeds. With respect to the geometric parameters, it was observed that neither the sweep angle nor the dihedral angle variations caused a substantial influence on the flutter speed, which is mainly supported by the resulting smaller variations in torsion and bending stiffness due to the geometric changes.
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Tahani, Mojtaba, Mehran Masdari, and Ali Bargestan. "Aerodynamic performance improvement of WIG aircraft." Aircraft Engineering and Aerospace Technology 89, no. 1 (January 3, 2017): 120–32. http://dx.doi.org/10.1108/aeat-05-2015-0139.
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Purpose This paper aims to investigate the aerodynamic characteristics as well as static stability of wing-in-ground effect aircraft. The effect of geometrical characteristics, namely, twist angle, dihedral angle, sweep angle and taper ratio are examined. Design/methodology/approach A three-dimensional computational fluid dynamic code is developed to investigate the aerodynamic characteristics of the effect. The turbulent model is utilized for characterization of flow over wing surface. Findings The numerical results show that the maximum change of the drag coefficient depends on the angle of attack, twist angle and ground clearance, in a decreasing order. Also, it is found that the lift coefficient increases as the ground clearance, twist angle and dihedral angle decrease. On the other hand, the sweep angle does not have a significant effect on the lift coefficient for the considered wing section and Reynolds number. Also, as the aerodynamic characteristics increase, the taper ratio befits in trailing state. Practical implications To design an aircraft, the effect of each design parameter needs to be estimated. For this purpose, the sensitivity analysis is used. In this paper, the influence of all parameter against each other including ground clearance, angle of attack, twist angle, dihedral angle and sweep angle for the NACA 6409 are investigated. Originality/value As a summary, the contribution of this paper is to predict the aerodynamic performance for the cruise condition. In this study, the sensitivity of the design parameter on aerodynamic performance can be estimated and the effect of geometrical characteristics has been investigated in detail. Also, the best lift to drag coefficient for the NACA 6409 wing section specifies and two types of taper ratios in ground effect are compared.
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Traub, Lance W. "Effects of Anhedral and Dihedral on a 75-deg Sweep Delta Wing." Journal of Aircraft 37, no. 2 (March 2000): 302–12. http://dx.doi.org/10.2514/2.2594.
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Gili, Piero A., and Manuela Battipede. "Experimental Validation of the Wing Dihedral Effect Using a Whirling Arm Equipment." Journal of Aircraft 38, no. 6 (November 2001): 1069–75. http://dx.doi.org/10.2514/2.2874.
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Paranjape, Aditya A., Soon-Jo Chung, and Joseph Kim. "Novel Dihedral-Based Control of Flapping-Wing Aircraft With Application to Perching." IEEE Transactions on Robotics 29, no. 5 (October 2013): 1071–84. http://dx.doi.org/10.1109/tro.2013.2268947.
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Chen, Xiao Jie. "Study on Wing Layout Design of Aircraft." Applied Mechanics and Materials 178-181 (May 2012): 2881–84. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.2881.
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This paper describes how the wing surfaces are defined by aerodynamic, stability/control, layout and structural requirements. The size of the wing (area) will usually be dictated by aircraft performance requirements(e.g. field length) but the shape of the planform and other geometry may be influenced by wing layout factors. In the early design stages choices need to be made on the position of the wing relative to the fuselage (e.g. high, mid or low position) and then on the overall envelope. This will include selection of aspect ratio, taper ratio, sweepback angle, thickness ratio and section profile, and dihedral. Each of these decisions is explained. A brief introduction on flap design of the aerodynamic (lift and drag) characteristics of flaps are also described, which is added to explain the wing layout of aircraft.
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Wang, Shizhao, Guowei He, and Tianshu Liu. "Estimating lift from wake velocity data in flapping flight." Journal of Fluid Mechanics 868 (April 15, 2019): 501–37. http://dx.doi.org/10.1017/jfm.2019.181.
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The application of the Kutta–Joukowski (KJ) theorem to estimating the lift of a flying animal based on wake velocity fields often leads to significant underprediction of the lift, which is known as the wake momentum paradox. This work attempts to answer the puzzling question on whether the KJ theorem is legitimate in its use for complex viscous unsteady wakes generated by flapping wings. The limitations in applying the KJ theorem to flapping wings are quantitatively examined through numerical simulations of viscous incompressible flows over three flapping wing models. The three flapping wing models studied in this work are a flapping wing with a fixed wingspan, a flapping wing with a dynamically changing wingspan and a dihedral flapping wing. The KJ theorem fails to give a satisfactory prediction of the time-averaged lift unless an effective span length is correctly computed. We propose a wake-sectional Kutta–Joukowski (WS-KJ) model to predict the time-averaged lift, where the effective span length is computed based on the time-averaged distance between the streamwise vorticity centroids in the right and left half sides of the Trefftz plane. The WS-KJ model incorporates the spatial evolutionary effects of the complex vortex structures in the wake and significantly improves the prediction of the time-averaged lift. The physical foundation for such improvement is explored. In addition, the time-dependent amplitude and phase changes of the unsteady lift are discussed as the fluid acceleration effect.
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Shankar, K. Shiva, M. Ganesh, and P. Sai Prashant. "Static and Dynamic Analysis for a Swept Back Dihedral Wing and its Optimization." IOP Conference Series: Materials Science and Engineering 455 (December 19, 2018): 012031. http://dx.doi.org/10.1088/1757-899x/455/1/012031.
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Gatto, A., P. Bourdin, and M. I. Friswell. "Experimental Investigation into the Control and Load Alleviation Capabilities of Articulated Winglets." International Journal of Aerospace Engineering 2012 (2012): 1–15. http://dx.doi.org/10.1155/2012/789501.
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An experimental investigation into the real-time flow and control characteristics of a flying wing with articulated winglets is described in this paper. The philosophy of the concept centres around the use of active, in-flight adjustment of each wing's winglet dihedral angle, both as a primary means of aircraft roll control (single winglet actuation) and though smaller equal and simultaneous winglet deflections, tailor and alleviate main wing load. Results presented in this paper do provide good evidence of the concept's ability to adequately perform both tasks, although for the current chosen wing/winglet configuration, roll control authority was unable to achieve, per unit of control surface deflection, the same level of performance set by modern aileron-based roll control methodologies.
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Luong, Quang Huan, Jeremy Jong, Yusuke Sugahara, Daisuke Matsuura, and Yukio Takeda. "A Study on the Relationship between the Design of Aerotrain and Its Stability Based on a Three-Dimensional Dynamic Model." Robotics 9, no. 4 (November 19, 2020): 96. http://dx.doi.org/10.3390/robotics9040096.
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A new generation electric high-speed train called Aerotrain has levitation wings and levitates under Wing-in-Ground (WIG) effect along a U-shaped guideway. The previous study found that lacking knowledge of the design makes the prototype unable to regain stability when losing control. In this paper, the nonlinear three-dimensional dynamic model of the Aerotrain based on the rigid body model has been developed to investigate the relationship between the vehicle body design and its stability. Based on the dynamic model, this paper considered an Aerotrain with a horizontal tail and a vertical tail. To evaluate the stability, the location and area of these tails were parameterized. The effects of these parameters on the longitudinal and directional stability have been investigated to show that: the horizontal tail gives its best performance if the tail area is a function of the tail location; the larger vertical tail area and (or) the farther vertical tail location will give better directional stability. As for the lateral stability, a dihedral front levitation wing design was investigated. This design did not show its effectiveness, therefore a control system is needed. The obtained results are useful for the optimization studies on Aerotrain design as well as developing experimental prototypes.
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Lamar, J. "A career in vortices and edge forces." Aeronautical Journal 116, no. 1176 (February 2012): 101–52. http://dx.doi.org/10.1017/s0001924000006667.
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Abstract This lecture recognises the background and distinguished work of Frederick William Lanchester, and notes that my background has a few similarities with his. These include a shared interest in wings, lift and vortices. My career at the NASA Langley Research Center spans the time-frame from America’s Super Sonic Transport through 2009. An early emphasis involved wind-tunnel testing of research aircraft models and the development of computer codes for subsonic aerodynamics of wing planforms. These attached-flow codes were applied to various configurations, including those with variable-sweep, dihedral, and more than one planform in both the analysis- and design-modes. These codes were used to provide a connection between leading-edge-forces and the associated additional lift on delta-wings with shed-vortex systems through the leading-edge suction analogy of Edward C. Polhamus. Subsequently, I extended the suction analogy to configurations with side-edges to predict the vortical-flow aerodynamics on complex configurations, including wing-strake combinations. These analysis codes could also be used in a design-by-analysis mode for configurations with leading-edge shed vortices. Later, I was involved in vortical-flow flight research with the F-106B and the F-16XL aircraft at cruise and maneuver conditions. Associated CFD predictions, generated by me and other members of the RTO/AVT-113 task group, have increased our understanding of the flight flow-physics measured on the F-16XL aircraft.
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Roy, D., Priyank Kumar, and Sudip Das. "Effect of Anhedral–Dihedral Angles on 76-40° Double-Delta Wing at Low Speeds." Journal of Aerospace Engineering 32, no. 6 (November 2019): 04019091. http://dx.doi.org/10.1061/(asce)as.1943-5525.0001079.
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Cheung, C. W. "Numerical Computation of Subsonic Oscillatory Airforce Coefficients for Wing-Winglet Configurations." Journal of Algorithms & Computational Technology 1, no. 3 (October 2007): 303–28. http://dx.doi.org/10.1260/174830107782424093.
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This paper presents the theoretical development and numerical results of a lifting-surface theory for calculating oscillating airforce coefficients for wing-winglet configurations and it follows the author's previous paper on the extension of Davies' T-tail theory for cruciform-tail configurations. The wing-winglet configurations are assumed to vibrate in a simple harmonic motion of infinitesimal amplitude in a subsonic airstream such that linearised aerodynamic theory is applicable for the analysis of the motion. The modes of displacement of the wing-winglet configuration may be either symmetric or antisysmmetric with respect to the centre-line of the configuration in the direction of the flow. A computer program has been developed for the evaluation of oscillatory airforce coefficients for wing-winglet configurations. Aerodynamic stiffness and damping matrices which are normally used for aeroelastic calculations have been obtained for a typical transport aircraft wing-winglet configuration at two winglet dihedral angles and comparisons have been made against those calculated by an alternative doublet-lattice method. The comparisons have been shown to be satisfactory.
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Song, Lei, Hua Yang, Yang Zhang, Haoyu Zhang, and Jun Huang. "Dihedral influence on lateral–directional dynamic stability on large aspect ratio tailless flying wing aircraft." Chinese Journal of Aeronautics 27, no. 5 (October 2014): 1149–55. http://dx.doi.org/10.1016/j.cja.2014.08.003.
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Kaparos, Pavlos, Charalampos Papadopoulos, and Kyros Yakinthos. "Conceptual design methodology of a box wing aircraft: A novel commercial airliner." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 232, no. 14 (August 24, 2018): 2651–62. http://dx.doi.org/10.1177/0954410018795815.
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In this work, the development of a conceptual design methodology of an innovative aircraft configuration, known as box wing, is presented. A box wing aircraft is based on a continuous-surface nonplanar wing formation with no wing-tips. The A320 medium range conventional cantilever wing aircraft is used as both the reference aircraft and the main competitor of the box wing aircraft. Based on the A320 characteristics and dimensions, a complete aerodynamic analysis of the box wing configuration is made by means of layout design and computational fluid dynamics studies, highlighting the aerodynamic and operating advantages of the box wing configuration compared to the A320 aircraft. The aspect ratio and the Oswald factor of a box wing aircraft differ significantly from the corresponding ones of A320 and provide increased aerodynamic performance. The increased aerodynamic performance leads by consequence, to lower fuel consumption, thus allowing longer range for the same payload or greater payload for the same range, contributing to the efforts for greener environment. In this work, the design methodology begins by estimating the critical initial design parameters, such as aspect ratio, dihedral angle, sweep angle, and taper ratio, which are continuously refined via an iterative process based on a conceptual design study. Various flying scenarios are studied using computational fluid dynamics and analytical calculations, in order to compare the performance of the box wing and the conventional A320, having always the same mission and payload conditions. The conceptual results show that the novel box wing configuration has considerable aerodynamic performance advantages compared to the conventional A320 aircraft.
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Feshalami, Behzad Forouzi, MH Djavareshkian, Masoud Yousefi, AH Zaree, and AA Mehraban. "Experimental investigation of flapping mechanism of the black-headed gull in forward flight." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 12 (December 27, 2018): 4333–49. http://dx.doi.org/10.1177/0954410018819292.
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Many developments in aerospace science have originated from nature. One of these developments has been obtained through inspirations from flying locomotion. The aim of this study is to simulate the flapping mechanism of the black-headed gull in forward flight. The wing of the black-headed gull is characterized entirely by complex dihedral, dividing the wing into two distinct parts. Hence, a flapping mechanism with different bending deflection angles is constructed and compared with a primitive flapping mechanism. Firstly, parametric studies are conducted to assess the role of flapping frequency, velocity and bending deflection angle on the lift, thrust and power loading of the membrane flexible wing at 10 ° angle of attack. Secondly, dimensional analysis is used to establish the similarity between the real gull and the constructed mechanism. Superiority of the bending deflection mechanism is concluded in forward flight against simple flapping wing in terms of aerodynamic forces as well as power loading parameter. It is found that although the aerodynamic coefficients decrease with increase in advance ratio, the best power loading of the black-headed gull is obtained between advance ratio of 2 and 3, in the gull's aerodynamically quasi-steady regime.
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Sugar-Gabor, O. "A general numerical unsteady non-linear lifting line model for engineering aerodynamics studies." Aeronautical Journal 122, no. 1254 (June 6, 2018): 1199–228. http://dx.doi.org/10.1017/aer.2018.57.
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ABSTRACTThe lifting-line theory is widely used for obtaining aerodynamic performance results in various engineering fields, from aircraft conceptual design to wind-power generation. Many different models were proposed, each tailored for a specific purpose, thus having a rather narrow applicability range. This paper presents a general lifting-line model capable of accurately analysing a wide range of engineering problems involving lifting surfaces, both steady-state and unsteady cases. It can be used for lifting surface with sweep, dihedral, twisting and winglets and includes features such as non-linear viscous corrections, unsteady and quasi-steady force calculation, stable wake relaxation through fictitious time marching and wake stretching and dissipation. Possible applications include wing design for low-speed aircraft and unmanned aerial vehicles, the study of high-frequency avian flapping flight or wind-turbine blade design and analysis. Several validation studies are performed, both steady-state and unsteady, the method showing good agreement with experimental data or numerical results obtained with more computationally expensive methods.
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Syamsuar, Sayuti. "Simulasi dan Verifikasi Prestasi Terbang Model Remote Control Flying Boat Saat Hidroplaning." WARTA ARDHIA 42, no. 1 (September 23, 2017): 1. http://dx.doi.org/10.25104/wa.v42i1.294.1-6.
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Pesawat Wing In Surface Effect A2B tipe B konfigurasi Lippisch mempunyai hambatan air yang cukup besar dibandingkan tenaga mesin saat hydroplaning. Makalah ini berisikan bagian dari analisis dalam perancangan untuk mengetahui karakteristik aerodinamika dan hidrodinamika dari remote control model jenis Flying Boat pada fase hydroplaning. Pada awalnya, dilakukan pemotretan 3D terhadap pesawat model Flying Boat menggunakan kamera laser untuk menghasilkan solid drawing pada program CATIA. Model 3D dianalisis dengan menggunakan piranti lunak CFx pada program AnSys. Planform sayap, memiliki dihedral dan menggunakan airfoil jenis NACA 23012. Karakteristik aerodinamika dan hidrodinamika untuk model 3 D dipresentasikan pada posisi sudut alpha =00. Sedangkan kecepatan yang digunakan adalah 0 sampai25 knots. Untuk memverifikasi data hasil simulasi, digunakan data uji terbang pesawat udara tanpa awak Alap-alap yang mempunyai T/W rasio yang sama, yaitu sudut pitch, kecepatan arah sumbu Z pada sumbu benda, ketinggian dan kecepatan. Gaya angkat aerodimaka arah sumbu Z pada simulasi RC model Flying Boat sebanding dengan gaya angkat aerodinamika arah sumbu Z pada UAV Alap-alap saat take off.
[The Hydroplaning Flight Performance Simulation and Verfication of a Flying Boat Remote Control Model] The Wing in Surface Effect Aircraft A2B type B with Lippisch configuration has higher hydrodynamics drag compared to engine powered aircraft during hydroplaning. This paper explains parts of analysis in aircraft design to identify the aerodynamics and hydrodynamics characteristics of flying boat remote control model during hydroplaning phase. At first, flying boat model was three dimensional photographed using laser camera in order to produce solid drawing for CATIA program. The three dimensional model, later, analyzed by using CFx software in AnSys program. The wing planform has dihedral angle while the airfoil used is NACA 23012. The aerodynamics and hydrodynamics characteristics of this three-dimensional model is represented for alpha =00. Whilst the speed used in simulation was 0 to 25 knots. In verifying the data of the simulation results, the Unmanned Aerial Vehicle UAV Alap-alap flight test data was used in which it has the same T/W ratio for the pitch angle, acceleration in Z body axis, altitude, and speed. The aerodynamics lift in Z axis of flying boat model during simulation is proportional to the aerodynamics lift in Z axis of UAV Alap-alap during take-off.
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Goitia, Hasier, and Raúl Llamas. "Nonlinear vortex lattice method for stall prediction." MATEC Web of Conferences 304 (2019): 02006. http://dx.doi.org/10.1051/matecconf/201930402006.
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The stall behavior of an empennage is a crucial and conditioning factor for its design. Thus, the preliminary design of empennages requires a fast low-order method which reliably computes the stall behavior and which must be sensitive to the design parameters (taper, sweep, dihedral, airfoil, etc.). Handbook or semi-empirical methods typically have a narrow scope and low fidelity, so a more general and unbiased method is desired. This paper presents a nonlinear vortex lattice method (VLM) for the stall prediction of generic fuselage-empennage configurations which is able to compute complete aerodynamic polars up to and beyond stall. The method is a generalized form of the van Dam algorithm, which couples the potential VLM solution with 2.5D viscous data. A novel method for computing 2.5D polars from 2D polars is presented, which extends the traditional infinite swept wing theory to finite wings, relying minimally on empirical data. The method has been compared to CFD and WTT results, showing a satisfactory degree of accuracy for the preliminary design of empennages.
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Cipolla, Vittorio, Karim Abu Salem, and Filippo Bachi. "Preliminary stability analysis methods for PrandtlPlane aircraft in subsonic conditions." Aircraft Engineering and Aerospace Technology 91, no. 3 (March 4, 2019): 525–37. http://dx.doi.org/10.1108/aeat-12-2017-0284.
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Purpose The present paper aims to assess the reliability and the limitations of analysing flight stability of a box-wing aircraft configuration known as PrandtlPlane by means of methods conceived for conventional aircraft and well known in the literature. Design/methodology/approach Results obtained by applying vortex lattice methods to PrandtlPlane configuration, validated previously with wind tunnel tests, are compared to the output of a “Roskam-like” method, here defined to model the PrandtlPlane features. Findings The comparisons have shown that the “Roskam-like” model gives accurate predictions for both the longitudinal stability margin and dihedral effect, whereas the directional stability is always overestimated. Research limitations/implications The method here proposed and related achievements are valid only for subsonic conditions. The poor reliability related to lateral-directional derivatives estimations may be improved implementing different models known from the literature. Practical implications The possibility of applying a faster method as the “Roskam-like” one here presented has two main implications: it allows to implement faster analyses in the conceptual and preliminary design of PrandtlPlane, providing also a tool for the definition of the design space in case of optimization approaches and it allows to implement a scaling procedure, to study families of PrandtlPlanes or different aircraft categories. Social implications This paper is part of the activities carried out during the PARSIFAL project, which aims to demonstrate that the introduction of PrandtlPlane as air transport mean can fuel consumption and noise impact, providing a sustainable answer to the growing air passenger demand envisaged for the next decades. Originality/value The originality of this paper lies in the attempt of adopting analysis method conceived for conventional airplanes for the analysis of a novel configuration. The value of the work is represented by the knowledge concerning experimental results and design methods on the PrandtlPlane configuration, here made available to define a new analysis tool.
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Wang, C., H. H. Khodaparast, M. I. Friswell, and A. D. Shaw. "Compliant structures based on stiffness asymmetry." Aeronautical Journal 122, no. 1249 (January 14, 2018): 442–61. http://dx.doi.org/10.1017/aer.2017.144.
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ABSTRACTOne of the key problems in the development of morphing aircraft is the morphing structure, which should be able to carry loads and change its geometry simultaneously. This paper investigates a compliant structure, which has the potential to change the dihedral angle of morphing wing-tip devices. The compliant structure is able to induce deformation by unsymmetrical stiffness allocation and carry aerodynamic loads if the total stiffness of the structure is sufficient.The concept has been introduced by building a simplified model of the structure and deriving the analytical equations. However, a properly designed stiffness asymmetry, which is optimised, can help to achieve the same deformation with a reduced actuation force.In this paper, round corrugated panels are used in the compliant structure and the stiffness asymmetry is introduced by changing the geometry of the corrugation panel. A new equivalent model of the round corrugated panel is developed, which takes the axial and bending coupling of the corrugated panel into account. The stiffness matrix of the corrugated panel is obtained using the equivalent model, and then the deflections of the compliant structure can be calculated. The results are compared to those from detailed finite element models built in the commercial software Abaqus. Samples with different geometries were manufactured for experimental tests.After verifying the equivalent model, optimisation is performed to find the optimum geometries of the compliant structures. The actuation force of a single compliant structure is first optimised, and then the optimisation is performed for a compliant structure consisting of multiple units. A case study is used to show the performance improvement obtained.
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Wilga, C. D., and G. V. Lauder. "Three-dimensional kinematics and wake structure of the pectoral fins during locomotion in leopard sharks Triakis semifasciata." Journal of Experimental Biology 203, no. 15 (August 1, 2000): 2261–78. http://dx.doi.org/10.1242/jeb.203.15.2261.
Full textAbstract:
The classical theory of locomotion in sharks proposes that shark pectoral fins are oriented to generate lift forces that balance the moment produced by the oscillating heterocercal tail. Accordingly, previous studies of shark locomotion have used fixed-wing aircraft as a model assuming that sharks have similar stability and control mechanisms. However, unlike airplanes, sharks are propelled by undulations of the body and tail and have considerable control of pectoral fin motion. In this paper, we use a new approach to examine the function of the pectoral fins of leopard sharks, Triakis semifasciata, during steady horizontal swimming at speeds of 0.5-2.0ls(−1), where l is total body length, and during vertical maneuvering (rising and sinking) in the water column. The planar orientation of the pectoral fin was measured using three-dimensional kinematics, while fluid flow in the wake of the pectoral fin and forces exerted on the water by the fin were quantified using digital particle image velocimetry (DPIV). Steady horizontal swimming in leopard sharks is characterized by continuous undulations of the body with a positive body tilt to the flow that decreases from a mean of 11 degrees to 0.6 degrees with increasing flow speeds from 0. 5 to 2.0ls(−1). Three-dimensional analysis showed that, during steady horizontal locomotion, the pectoral fins are cambered, concave downwards, at a negative angle of attack that we predict to generate no significant lift. Leopard shark pectoral fins are also oriented at a substantial negative dihedral angle that amplifies roll moments and hence promotes rapid changes in body position. Vortices shed from the trailing edge of the pectoral fin were detected only during vertical maneuvering. Starting vortices are produced when the posterior plane of the pectoral fin is actively flipped upwards or downwards to initiate rising or sinking, respectively, in the water column. The starting vortex produced by the pectoral fin induces a pitching moment that reorients the body relative to the flow. Body and pectoral fin surface angle are altered significantly when leopard sharks change vertical position in the water column. Thus, locomotion in leopard sharks is not analogous to flight in fixed-wing aircraft. Instead, a new force balance for swimming leopard sharks is proposed for steady swimming and maneuvering. Total force balance on the body is adjusted by altering the body angle during steady swimming as well as during vertical maneuvering, while the pectoral fins appear to be critical for initiating maneuvering behaviors, but not for lift production during steady horizontal locomotion.
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Syamsuar, Sayuti. "Karakteristik Aerodinamika Flying Boat pada Ketinggian Ground Effect (Studi Kasus Model Remote Control Flying Boat Pada Ketinggian 0,2 m dan 1 m)." WARTA ARDHIA 41, no. 3 (August 16, 2017): 139. http://dx.doi.org/10.25104/wa.v41i3.151.139-146.
Full textAbstract:
The paper presents an analysis of the flight performance and stability
and control of a Flying Boat remote control model on the ground effect altitude. It begins with a three dimensional measurement of a Flying Boat remote control model by using a laser tracking photo camera and a drawing software. The 3 D model was drawn by solid drawing on the CATIA software. The 3 D model was analyzed by using computational fluid dynamics CFx AnSys due to the rectangular wing with dihedral configuration with NACA 23012 airfoil. The maximum takeoff weight is around 25.0 kg powered with a single engine propeller, 5.5 HP. The surface effect phenomena of the Flying
Boat remote control model was simulated by using CFx omputational Fluid Dynamics software, AnSys with the airspeed, V = 35.0 knots and shows a good results at the altitude of 20.0 cm. The longitudinal static stability analysis provides a good result at 1.0 meter altitude. Simulations were performed to the PUNA “Alap alap” flight performance test during cruise at 7800 feet as data verification. The adaptive ground effect control system is solved by transfer function equation matrix.
Keywords: Flying Boat, remote control model, ground effect altitude.
Makalah ini berisikan analisis prestasi terbang dan kestabilan dari
pesawat remote control model jenis Flying Boat pada ketinggian terbang ground effect. Pada awalnya, dilakukan pemotretan 3 D terhadap pesawat model Flying Boat menggunakan kamera laser beserta piranti lunak pendukung dan kemudian menggunakan solid drawing pada program CATIA. Model 3D dianalisis dengan menggunakan piranti lunak CFx AnSys untuk keseluruhan badan dan sayap dengan airfoil jenis NACA 23012. Karakteristik dinamik dari pesawat model dengan MTOW = 25.0 kg dengan power 5.5 HP terlihat dengan baik pada ketinggian terbang 20.0 cm dengan
kecepatan, V = 35.0 knots. Sedangkan, analisis kestabilan statik matra longitudinal terlihat dengan respons waktu (t) yang baik pada ketinggian terbang 1.0 meter. Simulasi terbang menampilkan uji prestasi terbang pesawat nir awak PUNA “Alap alap” saat cruise pada ketinggian 7800 feet sebagai data verifikasi. Model matematika sistem Kendali Terbang Adaptif Ground Effect dianalisis dengan matriks persamaan fungsi transfer.
Kata kunci: Flying Boat, remote control model, ketinggian terbang
ground effect.
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ISHIZUKA, Tomoyuki, Yasuaki KOHAMA, Takuma KATOH, and Satoshi KIKUCHI. "106 Aerodynamic Characteristics of Aero-Train Wings With Dihedral Angle." Proceedings of Conference of Tohoku Branch 2004.39 (2004): 12–13. http://dx.doi.org/10.1299/jsmeth.2004.39.12.
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Brinda, Rajeev Mudakavi, Deepak Chopra, M. Srinivas Murthy, and T. N. Guru Row. "4-Methyl-2,6-bis(2-naphthylmethylene)cyclohexan-1-one." Acta Crystallographica Section E Structure Reports Online 63, no. 11 (October 31, 2007): o4494. http://dx.doi.org/10.1107/s1600536807053032.
Full textAbstract:
The molecular skeleton of the title molecule, C29H24O, has a `bird-like' general conformation. The naphthyl units (`wings') make a dihedral angle of 46.1 (1)°. The central cyclohexanone ring adopts an envelope conformation.
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Лисенко, Андрій Михайлович, and Ілля Станіславович Кривохатько. "Wings` dihedral angle effect on the aerodynamic characteristics of tandem-scheme UAV." Information systems, mechanics and control, no. 19 (October 15, 2018): 66–75. http://dx.doi.org/10.20535/2219-3804192018169439.
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Andronikos, Theodore, and Alla Sirokofskich. "The Connection between the PQ Penny Flip Game and the Dihedral Groups." Mathematics 9, no. 10 (May 14, 2021): 1115. http://dx.doi.org/10.3390/math9101115.
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This paper is inspired by the PQ penny flip game. It employs group-theoretic concepts to study the original game and its possible extensions. In this paper, it is shown that the PQ penny flip game can be associated, in a precise way, with the dihedral group D8 and that within D8 there exist precisely two classes of equivalent winning strategies for Q. This is achieved by proving that there are exactly two different sequences of states that can guarantee Q’s win with probability 1.0. It is demonstrated that the game can be played in every dihedral group D8n, where n≥1, without any significant change. A formal examination of what happens when Q can draw their moves from the entire U(2), leads to the conclusion that, again, there are exactly two classes of winning strategies for Q, each class containing an infinite number of equivalent strategies, but all of them sending the coin through the same sequence of states as before. Finally, when general extensions of the game, with the quantum player having U(2) at their disposal, are considered, a necessary and sufficient condition for Q to surely win against Picard is established: Q must make both the first and the last move in the game.
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Kryvokhatko, Illia. "Aerodynamic moment characteristics of tandem-scheme aircraft." MATEC Web of Conferences 304 (2019): 02015. http://dx.doi.org/10.1051/matecconf/201930402015.
Full textAbstract:
Aerodynamic interference between forward and back wings of tandem-scheme aircraft significantly affects its pitch and roll moments. The interference increases roll stability in a narrow range of sideslip angles; there is a kink on the dependence of roll moment coefficient versus sideslip angle (that is not observed for conventional-scheme aircraft). Directional stability is decreased by a dihedral angle of forward wings and winglets on them but is increased by the same factors for back wings. If back wings’ bending is significant, then aerodynamic interference may affect directional stability as well. The vortex system of tandem-wings at a sideslip angle was modeled incorrectly by the used CFD method (solving RANS), and further research is needed. The analytical and experimental methods show a good agreement concerning moment characteristics.
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Kang, Chi-Hang. "A Study of Wind Tunnel Test of a Korean Traditional Bangpae Kite with the Wind Hole and Spanwise Curved Dihedral." Journal of the Korean Society for Aeronautical & Space Sciences 39, no. 9 (September 1, 2011): 866–70. http://dx.doi.org/10.5139/jksas.2011.39.9.866.
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SUGAR GABOR, Oliviu. "Nonlinear Lifting-Line Model using a Vector Formulation of the Unsteady Kutta-Joukowski Theorem." INCAS BULLETIN 11, no. 1 (March 5, 2019): 189–203. http://dx.doi.org/10.13111/2066-8201.2019.11.1.15.
Full textAbstract:
In this paper, a vector form of the unsteady Kutta-Joukowski theorem is derived and then used in the formulation of a general Lifting-Line Model capable of analysing a wide range of engineering problems of interest. The model is applicable to investigating lifting surfaces having low to moderate sweep, dihedral, out-of-plane features such as winglets, in both steady-state and unsteady cases. It features corrections of the span-wise circulation distribution based on available two-dimensional aerofoil experimental data, and stable wake relaxation through fictitious time marching. Potential applications include the conceptual and initial design of low-speed Unmanned Aerial Vehicles, the study of flapping flight or Wind Turbine blade design and analysis. Several verification and validation cases are presented, showing good agreement with experimental data and widely-used computational methods.
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Duport, Chloé, Jean-Baptiste Leroux, Kostia Roncin, Christian Jochum, and Yves Parlier. "Benchmarking of a 3D non-linear lifting line method against 3D RANSE simulations." La Houille Blanche, no. 5-6 (December 2019): 70–73. http://dx.doi.org/10.1051/lhb/2019029.
Full textAbstract:
As a part of the design and operation of kites as auxiliary propulsion of vessels, it is necessary to be able to quickly estimate the aerodynamic efforts along various trajectories. A 3D non-linear model based on the lifting line of Prandtl has been developed for this purpose. It allows these rapid calculations for wings with any laws for the dihedral angle, the twist, and the sweep angle, along the span, and for a general flight kinematic taking into account translation velocities and rotation rates. This model has been verified by comparison with 3D simulations performed with a Navier-Stokes solver. It gives satisfactory results in incidence and sideslip, with gaps of about 4% for forecasts lift. Special attention has been paid to the estimation of the accuracy of the provided numerical results.
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Wang, Chen, Hamed Haddad Khodaparast, Michael I. Friswell, Alexander D. Shaw, Yuying Xia, and Peter Walters. "Development of a morphing wingtip based on compliant structures." Journal of Intelligent Material Systems and Structures 29, no. 16 (June 19, 2018): 3293–304. http://dx.doi.org/10.1177/1045389x18783076.
Full textAbstract:
Compliant structures, such as flexible corrugated panels and honeycomb structures, are promising structural solutions for morphing aircraft. The compliant structure can be tailored to carry aerodynamic loads and achieve the geometry change simultaneously, while the reliability of the morphing aircraft can be guaranteed if conventional components and materials are used in the fabrication of the morphing structure. In this article, a compliant structure is proposed to change the dihedral angle of a morphing wingtip. Unsymmetrical stiffness is introduced in the compliant structure to induce the rotation of the structure. Trapezoidal corrugated panels are used, whose geometry parameters can be tailored to provide the stiffness asymmetry. An equivalent model of the corrugated panel is employed to calculate the deformation of the compliant structure. To provide the airfoil shape, a flexible honeycomb structure is used in the leading and trailing edges. An optimisation is performed to determine the geometry variables, while also considering the actuator requirements and the available space to instal the compliant structure. An experimental prototype has been manufactured to demonstrate the deformation of the morphing wingtip and conduct basic wind tunnel tests.
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Yahiaoui, Toufik, Toufik Zebbiche, Abderrazak Allali, and Mohamed Boun-jad. "Gas effect for oblique and conical shock waves at high temperature." Mathematical Modelling of Natural Phenomena 15 (2020): 73. http://dx.doi.org/10.1051/mmnp/2020036.
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The work focuses to develop a new numerical calculation program for determining the gas effect at high temperature instead air on the calculation of the oblique and conical shock waves parameters and make applications for various external and internal aerodynamics problems like, the calculation of the suitable intake adaptation parameters, dihedron and cone wave drag, aerodynamic coefficients of a pointed supersonic airfoil and oblique shock reflection without forgetting others no less important like the detonation propulsion and the dust explosion applications, where the high temperature gas effect is very important. All this for future aerodynamics (gas dynamics) like the phenomenon of climate change in the near and far future because of the enlargement progressive of the layer ozone hole which will lead to an increase in the temperature of the ambient medium, and by the environment pollution by the shining of the waste which will cause a new decomposition of gases from the ambient environment. Another interesting application for actual aerodynamics (gas dynamics) is the performance of tests in wind tunnels supplied by a combustion chamber making a reaction of gases giving a gas with new thermodynamics parameters which is not necessarily air. To make a calculation, the selected gases are H2, O2, N2, CO, CO2, H2O, NH3, CH4 and air. All shock parameters depend on the stagnation temperature, upstream Mach number, the thermodynamics of the used gas, dihedron and cone deviation and others parameters. The specific heat at constant pressure varies with the temperature and the selected gas. Gas is still considered as perfect. It is calorically imperfect, and thermally perfect, less than the molecules dissociation threshold. A comparison between the parameters of each gas and air is presented to choose the suitable gas witch giving good performances as required by design parameters instead air.
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Marensi, Elena, Pierre Ricco, and Xuesong Wu. "Nonlinear unsteady streaks engendered by the interaction of free-stream vorticity with a compressible boundary layer." Journal of Fluid Mechanics 817 (March 15, 2017): 80–121. http://dx.doi.org/10.1017/jfm.2017.88.
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The nonlinear response of a compressible boundary layer to unsteady free-stream vortical fluctuations of the convected-gust type is investigated theoretically and numerically. The free-stream Mach number is assumed to be of $O(1)$ and the effects of compressibility, including aerodynamic heating and heat transfer at the wall, are taken into account. Attention is focused on low-frequency perturbations, which induce strong streamwise-elongated components of the boundary-layer disturbances, known as streaks or Klebanoff modes. The amplitude of the disturbances is intense enough for nonlinear interactions to occur within the boundary layer. The generation and nonlinear evolution of the streaks, which acquire an $O(1)$ magnitude, are described on a self-consistent and first-principle basis using the mathematical framework of the nonlinear unsteady compressible boundary-region equations, which are derived herein for the first time. The free-stream flow is studied by including the boundary-layer displacement effect and the solution is matched asymptotically with the boundary-layer flow. The nonlinear interactions inside the boundary layer drive an unsteady two-dimensional flow of acoustic nature in the outer inviscid region through the displacement effect. A close analogy with the flow over a thin oscillating airfoil is exploited to find analytical solutions. This analogy has been widely employed to investigate steady flows over boundary layers, but is considered herein for the first time for unsteady boundary layers. In the subsonic regime the perturbation is felt from the plate in all directions, while at supersonic speeds the disturbance only propagates within the dihedron defined by the Mach line. Numerical computations are performed for carefully chosen parameters that characterize three practical applications: turbomachinery systems, supersonic flight conditions and wind tunnel experiments. The results show that nonlinearity plays a marked stabilizing role on the velocity and temperature streaks, and this is found to be the case for low-disturbance environments such as flight conditions. Increasing the free-stream Mach number inhibits the kinematic fluctuations but enhances the thermal streaks, relative to the free-stream velocity and temperature respectively, and the overall effect of nonlinearity becomes weaker. An abrupt deviation of the nonlinear solution from the linear one is observed in the case pertaining to a supersonic wind tunnel. Large-amplitude thermal streaks and the strong abrupt stabilizing effect of nonlinearity are two new features of supersonic flows. The present study provides an accurate signature of nonlinear streaks in compressible boundary layers, which is indispensable for the secondary instability analysis of unsteady streaky boundary-layer flows.
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Yen, Shun C., and Yu F. Fei. "Winglet Dihedral Effect on Flow Behavior and Aerodynamic Performance of NACA0012 Wings." Journal of Fluids Engineering 133, no. 7 (July 1, 2011). http://dx.doi.org/10.1115/1.4004420.
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This study investigates the effects of Reynolds number, angle of attack, and winglet dihedral (δ) on the smoke-streak flow patterns, surface oil-flow configurations, and aerodynamic performance of the wingleted wings. The airfoil is NACA 0012 and the winglet dihedral varies from −30° to 135°. The smoke-wire technique was utilized to visualize the three-dimensional flow structures. Furthermore, the effect of δ on the wingtip surface vortex was examined using the surface oil-flow scheme. The wingtip surface vortex was observed on a baseline wing using the smoke-streak flow and surface-oil flow visualization schemes. Moreover, the length of wingtip surface vortex (Lb) decreases with increasing δ for δ > 15° where Lb denotes the major axis of wingtip surface vortex. The maximum Lb/C of 1.2 occurs at δ = 15° which is about 42% higher than that of a baseline wing, where C represents the wing chord length. The high flow momentum expands the wingtip surface vortex toward the winglet when δ < 15°. However, the minimum Lb/C of 0.55 occurs at δ = 90° which is about 34% lower than that of a baseline wing because the wingtip surface vortex is squeezed intensely at high δ. The aerodynamic performance was measured using a force-moment balance. The experimental data indicates that the lift-drag ratio at stalling (CL/CD)stall and maximum lift-drag ratio (CL/CD)max occurs at δ = 90°.
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El-Salamony, Mostafa E., and Mohamed A. Aziz. "Impact of N-Shaped Wing Morphing on Solar-Powered Aircraft." Unmanned Systems, December 21, 2020, 1–12. http://dx.doi.org/10.1142/s2301385021500138.
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Generally, unmanned aerial vehicles and micro aerial vehicles depend on batteries or conventional fuel as a source of energy. These sources of energy have limited flight time, relatively high cost, and also a certain level of pollutants. Solar energy applied to aerial vehicles is an excellent alternative way to overcome other sources of energy’s disadvantage. This study aimed to design a solar-powered aerial vehicle to achieve continuous flight on Earth. The efficiency of the solar system is related to the absorbed sun rays. The concept of an anti-symmetric N-shaped morphing wing is a good idea to increase the collected solar energy during the daily sun path. But this comes with the penalty of side forces and moments due to the anti-symmetry of the wing. This paper introduces a study for two parameters that strongly affect the aerodynamics of the N-shaped morphing wing; the dihedral part angle and the dihedral part length. The impact of the dihedral angle decreases the lift coefficient and increases the drag coefficient. The impact of the morphing wing on the aircraft performance is also considered.
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Miklosovic, David S. "Analytic and Experimental Investigation of Dihedral Configurations of Three-Winglet Planforms." Journal of Fluids Engineering 130, no. 7 (July 1, 2008). http://dx.doi.org/10.1115/1.2948372.
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An analytic and experimental effort was undertaken to assess the effectiveness and efficiency of three winglets mounted chordwise to the tip of a rectangular wing. The winglets, with an aspect ratio of 4.6, were mounted on a half-span wing having an effective aspect ratio of 6.29. 13 configurations of varying dihedral arrangements were analyzed with a vortex lattice method and tested in a low-speed wind tunnel at a Reynolds number of 600,000. While the analytic method provided fair agreement with the experimental results, the predicted trends in lift, drag, and (to a lesser degree) pitching moment were in good agreement. The analytic distributions of wake velocity, circulation, and downwash angle verified that highly nonplanar configurations tended to reduce and diffuse the regions of highest circulation and to create more moderate downwash angles in the wake. This was manifest as an overall drag reduction. More specifically, the results showed that the winglets could be placed in various optimum orientations to increase the lift coefficient as much as 65% at the same angle of attack, decrease the drag coefficient as much as 54% at the same lift coefficient, or improve the maximum L∕D by up to 57%. The most dramatic findings from this study show that positioning the winglet dihedral angles had the result of adjusting the magnitude and slope of the pitching moment coefficient. These observations suggest that multiple winglet dihedral variations may be feasible for use as actively controlled surfaces to improve the performance of aircraft at various flight conditions and to “tune” the longitudinal stability characteristics of the configuration.
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Malik, Khurshid, Mohammed Aldheeb, Waqar Asrar, and Sulaeman Erwin. "Effects of Bio-Inspired Surface Roughness on a Swept Back Tapered NACA 4412 Wing." Journal of Aerospace Technology and Management, 2019. http://dx.doi.org/10.5028/jatm.v11.1021.
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This paper presents the overall pros and cons of the effect of surface roughness elements over a NACA 4412 tapered, swept back half wing with a sweep angle of 30º and a dihedral angle of 5º. The tests were conducted at a Reynolds number of 4 × 105 in the IIUM Low Speed wind tunnel. Different roughness sizes and roughness locations were tested for a range of angle of attack. Lift, drag and pitching moment coefficients were measured for the smooth wing and with roughness elements. Surface roughness delays the stall angle and decreases the lift. The wing with the roughness elements located at 75% to 95% of mean chord from leading edge shows minimum drag and maximum lift compared to other locations. Significant increase in the pitching moment coefficient was found for flexible roughness elements. In case of rigid surface roughness, the effect on pitching moment is small.
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Prakash, Ishaan, and Prithwish Mukherjee. "Aerodynamics, Stability and Performance Characteristics of X-Tandem Aircrafts." International Journal of Vehicle Structures and Systems 11, no. 1 (May 21, 2019). http://dx.doi.org/10.4273/ijvss.11.1.11.
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This paper details design, analysis and validation of tandem aircraft with one wing swept forward and the other wing swept backwards. The design objective is to investigate the aerodynamic and stability characteristics of this configuration created with the motive of exploiting the manoeuvring and post stall characteristics of a forward swept wing along with the structural robustness and reliable performance of the conventional aft-swept wing. Parameters such as wing sweep, wing position, anhedral and dihedral were varied to develop a range of designs. This gave considerable information regarding the aerodynamic and stability characteristics which enabled a preliminary design of a military combat aircraft exploiting this configuration. All performance characteristics and parameters of the final design compared with current operational military aircraft give a favourable picture regarding the effectiveness of this design.
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Bal, S. "Prediction of Hydrodynamic Performance of 3-D WIG by IBEM." International Journal of Maritime Engineering Vol 160 2018 A3 Vol 160, A3 (September 1, 2018). http://dx.doi.org/10.3940/rina.ijme.2018.a3.475.
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The hydrodynamic performance of three-dimensional WIG (Wing-In-Ground) vehicle moving with a constant speed above free water surface has been predicted by an Iterative Boundary Element Method (IBEM). IBEM originally developed for 3-D hydrofoils moving under free surface has been modified and extended to 3-D WIGs moving above free water surface. The integral equation based on Green's theorem can be divided into two parts: (1) the wing part, (2) free surface part. These two problems are solved separately, with the effects of one on the other being accounted for in an iterative manner. Both the wing part including the wake surface and the free surface part have been modelled with constant strength dipole and source panels. The effects of Froude number, the height of the hydrofoil from free surface, the sweep, dihedral and anhedral angles on the lift and drag coefficients are discussed for swept and V-type WIGs.
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Wang, Jie, and Niels P. Kruyt. "Effects of Sweep, Dihedral and Skew on Aerodynamic Performance of Low-Pressure Axial Fans With Small Hub-to-Tip Diameter Ratio." Journal of Fluids Engineering 144, no. 1 (July 28, 2021). http://dx.doi.org/10.1115/1.4051542.
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Abstract Axial fans with a small hub-to-tip diameter ratio are used in many branches of industry. Optimization of their aerodynamic performance is important, for which using sweep, dihedral, and skew of the blades' stacking line form an important method. Investigations on axial fans with medium to high hub-to-tip diameter ratio have shown that forward sweep of blades can give an improved aerodynamic performance, especially the total-to-total efficiency. However, only a few studies for fans with a small hub-to-tip diameter ratio have been reported. For such fans, extensive regions of backflow are present behind the fan near the hub. Based on a validated computational fluid dynamics simulation method, the effects of a sweep, dihedral and skew in axial and circumferential directions (in forward and backward direction) on the aerodynamic performance of small hub-to-tip ratio fans are investigated, with a linear stacking line. Current results show that forward sweep and circumferential skew are beneficial for higher total-to-total efficiency and that higher total-to-static efficiency can be obtained by forward dihedral and axial skew. The backward shape variety generally gives negative aerodynamic effects. Forward sweep and circumferential skew shorten the radial migration path, but more flow separation is present near the hub. With forward dihedral and axial skew, the backflow region is reduced in size and axial extent, but a more significant hub corner stall region is found. The pressure reduction due to sweep and dihedral is more limited than what could be expected from wing aerodynamics.