V-shaped Wings Research Articles

Swifts Form V-Shaped Wings While Dipping in Water to Fine-Tune Balance.

Swifts, a distinctive avian cohort, have garnered widespread attention owing to their exceptional flight agility. While their aerial prowess is well documented, the challenge swifts encounter while imbibing water introduces an intriguing complexity. The act of water uptake potentially disrupts their flight equilibrium, yet the mechanisms enabling these birds to maintain stability during this process remain enigmatic. In this study, we employed high-speed videography to observe swifts' water-drinking behavior. Notably, we observed that the swift adopts a dynamic V-shaped wing configuration during water immersion with the ability to modulate the V-shaped angle, thereby potentially fine-tuning their balance. To delve deeper, we utilized a three-dimensional laser scanner to meticulously construct a virtual 3D model of swifts, followed by computational fluid dynamics simulations to quantitatively assess the mechanical conditions during foraging. Our model indicates that the adoption of V-shaped wings, with a variable wing angle ranging from 30 to 60 degrees, serves to minimize residual torque, effectively mitigating potential flight instability. These findings not only enhance our comprehension of swifts' flight adaptability but also hold promise for inspiring innovative, highly maneuverable next-generation unmanned aerial vehicles. This research thus transcends avian biology, offering valuable insights for engineering and aeronautics.

Reducing shallow foundation rotation due to reverse faulting using predefined shear planes

Permanent ground displacement due to faulting during strong earthquakes threatens the stability of civil structures. To protect surface foundations from faulting, several mitigation techniques have been developed. Owing to the limitations of earlier mitigation strategies for unidentified reverse faulting conditions, this research presents a novel mitigation system, including the installation of sliders beneath the wings of a V-shaped concrete element, to reduce footing rotation. To evaluate the effectiveness of the suggested mitigation strategy, concrete strength tests, a physical centrifuge test and a comprehensive numerical study for different fault locations and dip angles were conducted for the first time. Results demonstrated that the placement of the sliders beneath the V-shaped wings had a significant effect on dissipating the fault dislocation. Compared to the previous mitigation techniques, the proposed system decreased the foundation rotation from a high value (11°) to a low value (3·2°) for the worst-case scenarios. Furthermore, the friction coefficients among sliders and concrete, the concrete wing inclination angle, length and thickness were critical parameters to design the optimum proposed system. In contrast, soil layer thickness and relative density did not significantly affect the footing rotation.

An innovative V-shaped piezoelectric energy harvester for wind energy based on the fully fluid–solid-electric coupling

In order to convert galloping-based vibration energy generated by wind flow into electricity more effectively, an innovative piezoelectric energy harvester (PEH) with V-shaped windward wings is proposed and designed to evaluate its performance in this paper. The V-shaped PEH mainly consists of three components: the main cantilever beam made of an aluminum plate, a piece of macro-fiber piezoelectric composite stuck to the end of the main cantilever beam as the key element of energy harvesting, and a pair of V-shaped windward wings as the structure of the bluff body to produce stronger and more regular vortices in wind flow. Wind tunnel experiments are conducted to evaluate its performance of the output voltages, and the results confirm that the angles of V-shaped wings have dramatically affected the behavior of energy harvesting. A pair of 60° angles was confirmed as the optimal angle for this V-shaped PEH, which can achieve the peak-to-peak value of alternating current voltage (VAC-PP) of more than 100 V when the wind velocity is 10 m/s. Subsequently, the fully fluid–solid-electric coupling for this corresponding two dimensional model is simulated by COMSOL Multiphysics, which expounds the mechanism of swing for this V-shaped PEH under the galloping-based vibration, as well as verifies the rationality of the experimental results.

In-plane elastic properties of a 2D chiral cellular structure with V-shaped wings

A 2D chiral cellular structure, the unit cell of which is composed of four V-shaped wings, is studied through the energy-based method. The closed-form solutions of the in-plane elastic constants are obtained as functions of geometric parameters and verified through finite element analysis. Furthermore, the influences of geometric parameters on the elastic constants are discussed. Results show that the equivalent moduli of the structure can be several orders of magnitude lower than those of the base material, and the maximum global strains can be dozens of times those of the base material. Besides, the structure shows significant in-plane elastic coupling effects: (1) the maximum ratio of the shear to elastic strain beyond 17.2°/% and (2) the maximum ratio of the elastic to shear strain exceeding 1.52%/° (x-direction) and 1.64%/° (y-direction). As a distinctive 2D chiral cellular structure, the structure shows great potential as a candidate selection for flexible structures in engineering applications.

Micropolar Modeling of Auxetic Chiral Lattices With Tunable Internal Rotation

Based on micropolar continuum theory, the closed-form stiffness tensor of auxetic chiral lattices with V-shaped wings and rotational joints were derived. Representative volume element (RVE) of the chiral lattice was decomposed into V-shape wings with fourfold symmetry. A unified V-beam finite element was developed to reduce the nodal degrees of freedoms of the RVE to enable closed-form analytical solutions. The elasticity constants were derived as functions of the angle of the V-shaped wings, nondimensional in-plane thickness of the ribs, and the stiffness of the rotational joints. The influences of these parameters on the coupled chiral and auxetic effects were systematically explored. The results show that the elastic moduli were significantly influenced by all three parameters, while Poisson's ratio was barely influenced by the in-plane thickness of the ribs but is sensitive to the angle of the V-shaped wings and the stiffness of the rotational springs. There is a transition region out of which the spring stiffness does not considerably affect the auxeticity and the overall lattice stiffness.

V-shaped wings with the central body in supersonic flow

The results of a theoretical investigation of the flow pattern of V-shaped wings at supersonic flow velocities are presented. Data are presented on the flow structure near V-shaped wings with a central body in the form of a part of a circular cone within the framework of the ideal gas model. The applicability of the criteria for the existence of nonviscid vortex structures has been determined, but with differences due to the shape of the body. Influence of the central body on the aerodynamic quality of its layout with a V-shaped wing was studied. A significant dependence of geometry of the optimal body on the lift coefficient was established.

Wings` dihedral angle effect on the aerodynamic characteristics of tandem-scheme UAV

In aviation the aircraft aerodynamic scheme tandem with comparable areas of front and rear wings is known. The aerodynamic tandem scheme benefits by lift and cargo capacity with limited wing widths. Due to this it has found a new application in modern unmanned aerial vehicles (UAVs). However, an increase in the number of bearing surfaces also leads to an increase in the aircraft frontal resistance due to their negative interference. To reduce the reciprocation of the wings, i.e. to increase the aerodynamic quality and the transverse and track resistance of aircraft, the V-shaped wings are used. Theoretically, if you give the wing-high-plane a positive V-shaped and wing-low-plane-negative, this will reduce the impact of the front wing to the rear. The experiment really proved the ability to significantly increase the aerodynamic quality in this way (ΔKmax = 1.0 or about 10%). But the possibility of calculating the effect of numerical methods remains questionable.

V-shaped wings in supersonic flow

The results of a comprehensive theoretical and experimental investigation of the flow pattern of V-shaped wings at supersonic flow velocities are presented. Applicability of the previously established criteria for the existence of nonviscid vortex structures in cases of formation of a contact discontinuity of a corresponding intensity, originating from the point of separation of the λ-configuration of shock waves, accompanying separation of the turbulent boundary layer, influenced by the internal compression shock incident on one of the wing panel, is shown. A wide variety of flow patterns in the shock layer near the wing with an opening angle [Formula: see text] depending on the Mach number, angles of attack and slip, which had not been previously described, was found. They, in particular, include: flow separation from the leeward console and presence of a vortex in the flow modes with a slip; flow transition on a sphere in the vicinity of the central chord of the wing from subsonic to trans- and supersonic one both along the contour of the vortex and in the return flow in a vortex near the wall of the lee console with the shock waves formation. An experimental investigation of the flow patterns with a vortex downstream the salient point of the outline qualitatively confirmed the calculation results on the flow structure outside the vortex. A separation of the turbulent boundary layer is revealed in the return flow within the vortex, due to the counter pressure gradient.

V-образные крылья с центральным телом в сверхзвуковом потоке

V-образные крылья с центральным телом в сверхзвуковом потоке

V-shaped wings with an opening angle exceeding π at super- and hypersonic flow velocities

The results of theoretical investigation of an ideal-gas asymmetrical flow around V-shaped wings with an opening angle exceeding π and having supersonic forward edges at all modes are presented.

Hypersonic flow past conical V-shaped wings

Hypersonic flow past delta wings with a V-shaped cross-section has been investigated both theoretically and experimentally. Much attention is given to the examination and classification of possible conical flow patterns in the vicinity of the windward surface using the thin shock layer method. Solutions for shocks both attached to and detached from the leading edges them are obtained. It is shown that qualitatively new flow patterns can appear in the flow past V-shaped wings as compared with the case of a planar wing.

Aerodynamic characteristics of V-shaped wings with shock waves detached from leading edges at hypersonic speeds

The direct problem of hypersonic flow past a V-shaped wing with a shock wave detached from the leading edges is solved. The reduced normal force coefficient and the lift-drag (L/D) ratio are calculated for a configuration with a lower part in the shape of a V-wing and a streamwise upper part.

Some supersonic flow regimes on the windward side of V-shaped wings

The conditions of realization of regimes, detected in ideal gas theory [1, 2], with a floating Ferri point on the windward side of a wing with supersonic leading edges and breakdown of the conical flow in the presence of turbulent boundary layer separation are studied using experimental data on the flow over conical V-shaped wings. The experiments were carried out on three models of V-shaped wings with sharp leading edges having a convergence angleγ=40°, apex anglesβ=30, 45, and 90° and lengths along the central chordL=100, 100, and 70 mm, respectively. The free-stream Mach numberM∞=3, and the unit Reynolds number Re=1.6 ·108 m−1. Boundary layer transition took place 10 mm from the leading edges of the models at a local Reynolds number Re=(1.5−2)·106. Thus, on most of the wing surface the inner shock waves interacted with a turbulent boundary layer. In the experiments we employed; optical methods, which made it possible to observe shadow flow patterns in a plane normal to the rib of the V-shaped wing [3], as well as in the wake behind the wing and its leading edges (Topler schlieren method); the oil-film visualization method for obtaining data on the position and dimensions of the separation zones and limiting streamline patterns on the surface of the model. The pressure distribution over the wing span was recorded by means of an automated data collection and processing system based on IKD6TD transducers. The errors of the pressure measurements did not exceed 1 %.

The flow structure near the windward side of V-shaped wings with an attached shock wave on the leading edges

The results of a numerical calculation of a symmetric flow of supersonic gas with the Mach number M=3 past the windward side of V-shaped wings with an opening angle γ=40° and apex angles β=30, 45, and 90° are given. The possibility of the ascent of one or two Ferri points from the break point of the transverse contour of the wing is discovered and explained. It is shown that conical flow near wings of finite length need not exist in flow regimes corresponding to angles of attack α at which a Ferri point ascends, while at angles of attack smaller and larger than a certain interval, conical flow will exist. The investigation is conducted by means of a numerical method of stabilization with an artificial viscosity. The longitudinal coordinate, relative to which the steady system of equations is hyperbolic, played the part of the time variable, usual for methods of stabilization. The numerical method constructed using the scheme of [1] is described in [2] and was successfully applied to the calculation of different regimes of supersonic flow past conical wings with supersonic leading edges [2–6]. In. the present investigation the calculation algorithm of [2] is modified and makes it possible to realize motion with respect to the parameter a, this being particularly important for the stabilization of the solution in the calculation of flow regimes for which regions with a total velocity Mach number close to unity arise in the flow.

Transonic swept wings studied by the lifting-line theory

Transonic swept wings are analyzed as a lifting-line problem under a small-disturbance approximation. Basic concepts and principal results of the asymptotic theory are discussed. The study focuses on straight oblique wings and V-shaped swept wings, of which the local centerline curvature can be equated to zero. The three-dimensional (3-D) perturbation of the nonlinear component flow admits a similarity flow structure but requires that all wing sections are generated from a single airfoil profile; the reduced 2-D problems in this case are solved only once for all span stations. Examples of solutions involving high subcritical and slightly supercritical component flows are demonstrated and compared with surface pressure data from 3-D computer codes based on the full-potential equation (FLO 22). Except in the neighborhood of leading edges, where the small-disturbance assumption breaks down, and in the vicinities of wing tips and the symmetry plane, where neither the theory nor the 3-D codes may claim full validity, reasonable agreement is consistently found. The explicit results from the upwash analysis, along with the similarity flow structure, provides a rational approach to the control of 3-D effects in transonic aerodynamic design studies.

Passage of a subsonic flow around V-shaped wings

In view of the problems involved in the design of hypersonic aircraft great interest has arisen in recent years as to the behavior of wings in fast supersonic flows. Two main approaches have been used: a study of hypersonic flow around traditional wings, and a search for new configurations with optimum aerodynamic properties. Aerodynamic [1, 2], heat-transfer [3], and stability investigations (for V-shaped wings in super- and hypersonic flows) belong to the latter category. Before attaining supersonic flight the aircraft has to overcome the range of subsonic velocities. In this connection it is important to study flow around V-shaped wings at M < 1. Little research has been devoted to flow around such configurations at subsonic velocities, principal attention having been directed at the study of rapid flow around aircraft configurations with V-shaped wings or tails. The results of analytical and numerical calculations allowing for the interference of transient aerodynamic forces acting on a V-shaped and mutiple-fin tail group in combination with the fuselage were presented in [4, 5]. An experimental study of V-shaped wings as regards the influence of the wing dihedral angle on the aerodynamic characteristics of a model aircraft was presented in [6, 7].

Experimental investigation of some singularities of the supersonic flow around V-shaped wings

Some results are presented of an experimental investigation of the stream configuration in a supersonic flow over the windward and leeward sides of V-shaped wings.

Linear problem for triangular and V-shaped wings

Linear problem for triangular and V-shaped wings

Calculation of supersonic flow around v-shaped wings by the fitting method

The problem of flow around a V-shaped wing with supersonic leading edges is solved. The method employed is that of fitting with respect to a space variable in which the system of equations of motion is hyperbolic, using the computing scheme of V. V. Rusanov, A comparison between the results of these calculations and experimental data in relation to the pressure distribution along the wing span reveals excellent agreement, except for a limited region, in which the compression jump incident on the plane of the wing interacts with the boundary layer. A comparison between the results obtained by means of the oblique-jump equations and by numerical calculations indicates that the method in question is reasonably accurate.

Calculation of the supersonic flow around conical bodies

A finite-difference scheme [1, 2], proposed previously for calculating spatial supersonic flows, which is written in spherical coordinates, is applied to the calculation of the supersonic flow around various conical bodies: circular, elliptic and almost pyramidal cones, triangular and V-shaped wings and combinations of a triangular wing and a circular cone. The solutions describing the corresponding conical flows are developed in the build-up process along the radial coordinate. The difference scheme used is direct, which enables us to perform the calculation without the isolation of internal shock waves, which are generated, for example, by the leeward (shady) side of the cones at fairly large angles of attack. At the same time the calculation of a leading shock wave, the isolation of which is advisable, does not require the inclusion in the computer program of any supplementary algorithm, since allowing for shock waves (rather, the interaction of two uniform supersonic flows) constitutes one of the elements of the difference scheme mentioned.