Showing papers on "Wing root published in 2001"

Three-Dimensional Transonic Aeroelasticity Using Proper Orthogonal Decomposition-Based Reduced-Order Models

Abstract: The proper orthogonal decomposition (POD) based reduced order modeling (ROM) technique for modeling unsteady frequency domain aerodynamics is developed for a large scale computational model of an inviscid flow transonic wing configuration. Using the methodology, it is shown that a computational fluid dynamic (CFD) model with over a three quarters of a million degrees of freedom can be reduced to a system with just a few dozen degrees of freedom, while still retaining the accuracy of the unsteady aerodynamics of the full system representation. Furthermore, POD vectors generated from unsteady flow solution snapshots based on one set of structural mode shapes can be used for different structural mode shapes so long as solution snapshots at the endpoints of the frequency range of interest are included in the overall snapshot ensemble. Thus, the snapshot computation aspect of the method, which is the most computationally expensive part of the procedure, does not have to be fully repeated as different structural configurations are considered.

Optimized Nonuniform Rational B-Spline Geometrical Representation for Aerodynamic Design of Wings

Abstract: The geometric representation and parameterization used in an aerodynamic wing design process determines the number of design variables and influences the smoothness of the wing representation. In an attempt to reduce the number of design variables while preserving good smoothness properties, the present research investigates the performance of an optimized nonuniform rational B-spline (NURBS) geometrical representation for the aerodynamic design of wings. As a first step, an approach is described whereby optimal spatial positions and weights of a fixed number of NURBS control points is determined using a quasi-Newton optimization algorithm to approximate a general airfoil section. The resulting optimized NURBS representation significantly reduces the number of design variables needed to define accurately a wing section while ensuring good smoothness properties. In a second step, the NURBS control point positions and weights are used as design variables in an aerodynamic optimization problem. This methodology results in a rapid and robust design process, as illustrated by examples of aerodynamic optimization for two- and three-dimensional cases

Three-Dimensional Navier-Stokes Simulations for Transport Aircraft High-Lift Configurations

Abstract: Computations of lift and drag polars for a transport aircraft wing/fuselage high-lift cone guration using the MEGAFLOWcodesystemarecarriedoutandcomparedtowind-tunnelexperiments.Themainemphasisislaidon acomparisonoftheblock-structuredandtheunstructuredcodemodulesforsuchtypeofapplication.FortheblockstructuredFLOWercodeincombinationwith a k‐! turbulencemodel,thenumericalresultsarein good agreement with the available experimental data in the linear CL range. Beyond 15-deg incidence, a strong separation near the e ap cut-out is simulated, leading to an underprediction of total lift near CL; max compared to the experimental data. In contrast to this, the results of the unstructured TAU code utilizing the Spalart ‐Allmaras turbulence model are characterized by a nearly constant lift overestimation up to maximum lift without the aforementioned separation tendency at moderate incidences. The lift overprediction in the unstructured results is attributed to the main wing and the slat upperside suction peaks, which are higher resolved by the unstructured grid. Neither code reproduces the lift breakdown beyond CL; max according to the experiments. The use of preconditioning in conjunction with theFLOWercodeshowsonly minorimprovement of theaccuracy,but considerabledeterioration of the convergence properties, requiring improvements for routine use. Further studies will focus on the ine uence of geometry simplie cations at the wing root in the theoretical models and its impact on the experimental evidence.

Optimum Spanloads Incorporating Wing Structural Weight

Abstract: The classic minimum induced drag spanload is not necessarily the best choice for an aircraft. Here, a discrete vortex method which finds the minimum induced drag in the Trefftz plane has been used to calculate optimum spanloads for non-coplanar multisurface configurations. The method includes constraints for lift coefficient, pitching moment coefficient and wing root bending moment. The wing root bending moment constraint has been introduced so that by holding wing geometry fixed, changes in wing weight can be related to variations in spanload distributions. Changes in wing induced drag and weight were converted to aircraft total gross weight and fuel weight benefits, so that the spanloads that give maximum take-off gross weight reduction can be found. Results show that a reduction in root bending moment from a lift distribution that gives minimum induced drag leads to more triangular spanloads, where the loads are shifted towards the root, reducing wing weight and increasing induced drag. A slight reduction in root bending moment is always beneficial, since the initial increase in induced drag is very small compared to the decrease in wing weight. Total weight benefits were studied for a B-777 type configuration, obtaining take-off gross weight improvements of about 1% for maximum range missions. When performing reduced-range missions, improvements can almost double. A long range, more aerodynamically driven aircraft like the B-777 will experience lower benefits as a result of increasing drag. Short to medium range aircraft will profit the most from more triangular lift distributions.

Vortical Flowfield Structure at Forward Swept Wing Configurations

Abstract: Extensive aerodynamic investigations have been carried out on forward swept-wing cone gurations with a wing sweep of i 40 deg. A generic wing-body model with removable aft swept canards is used to measure the instantaneous velocities in several crosse ow planes applying advanced hot-wire anemometry. The tests were made at 10-, 20-, and 30-deg angle of attack at a Reynolds number of 0 :46 £ 10 6 . Detailed surveys of mean and rms velocities show that at moderate angles of attack strong wing leading-edge vortices aregenerated rotating opposite in a sense to the wing tip vortices. At higher incidences trailing-edge vortices are shed at the inner-wing part with the same sense of rotation as the wing tip vortices. The canard vortices pass the wing leading-edge relatively high, and after theonset of wing vortices they are moved upward and outboard. Theinterferencebetween these vortices is studied in detail by analyzing the associated turbulent e ow structure. Vortex bursting over the wing occurs already at moderate angles of attack. Downstream, the highest turbulence intensities are found in an annular region around the burst vortex core, where e uctuations are signie cantly channeled into a narrow band.

3D RANS Simulations for Transport Aircraft High Lift Configurations

Abstract: Computations of lift and drag polars for a transport aircraft wing/fuselage high lift configuration using the MEGAFLOW code system are carried out and compared to windtunnel experiments. The main emphasis is laid on a comparison of the block-structured and the unstructured code modules for such type of application. For the block-structured FLOWer code in combination with a k-w turbulence model the numerical results are in good agreement with the available experimental data in the linear CL range. Beyond 150 incidence a strong separation near the flap cut-out is simulated, leading to an underprediction of total lift near CL, max compared to the experimental data. In contrast to this, the results ofthe unstructured TAU code utilizing the Spalart-Allmaras turbulence model are characterized by a nearly constant lift overestimation up to maximum lift without the aforementioned separation tendency at moderate incidences. The lift overprediction in the unstructured results is attributed to the main wing and the slat upperside suction peaks, which are higher resolved by the unstructured grid. Neither code reproduces the lift breakdown beyond CL, max according to the experiments. The use of preconditioning in conjunction with the FLOWer code shows only minor improvement of the accuracy, but considerable deterioration of the convergence properties, requiring improvements for routine use. Further studies will focus on the influence of geometry simplifications at the wing root in the theoretical models and its impact on the experimental evidence.

Structural loading of outbound-horizontal stabilizer aircraft relative to comparable conventional designs

Abstract: The objective was to study the aerodynamic and gravitational structural loadings, under steady, level, flight conditions, of aircraft with outboard horizontal-stabilizers (OHS). The aerodynamics of OHS configurations have been studied previously yielding results reported in the literature. The main reasons for interest in OHS configurations are explained briefly. The approach was based on evaluating by analytical means, structural loadings, predominantly, but not exclusively, consisting of wing-root bending moments and wing-root torsional loadings for OHS configurations. The corresponding, complementary, aerodynamic loadings were obtained from previously published data. The main conclusions from the work were that contrary to what might, at first glance, appear to be a problem OHS aircraft configurations do not suffer from excessive structural wing bending moments or torsional loadings relative to conventional designs of equal gross lift and main-plane (wing) aspect ratio nor do they appear to be more prone to flutter.

Experimental Validation of the Wing Dihedral Effect Using a Whirling Arm Equipment

Abstract: By the use of whirling arm equipment, tests have been carried out on a wing model equipped with a suitable strain-gauge balance. The purpose of this work was to verify analogous theoretic results from the dihedral effect trends (C 1β derivative), which were detected on a wing with generic geometry. Full details are put forward concerning the remarkable possibilities that this system offers for the experimental determination of all main aerodynamic derivatives in the state variables within the aircraft dynamics equations. The experimental facility induces a test situation, which calls for careful and in-depth result processing in addition to the normal corrections arising from Reynolds and Mach numbers. The results, presented as theoretical-experimental comparisons, strongly support the theoretic calculation

Nickel-titanium shape memorising fracture setting device

Abstract: A fracture setting device of nickel-titanium marmem takes the shape of a pair of neck-crossing swans. It consists of one fracture setting board assembly comprising fracture setting board and tail board; one axial neck pressing branck comprising head hook, outer barb, axial neck and neck root; and one bone holding wing assembly comprising wing root, wing fin and wing feathers. Before plantation, it produces plastic deformation at low temperaturs, and after plantation, body's temperature makes it produce metallurgical change and restore memorized shape so that the fracture part is set by means of the synergistic effect. The present invention can resist shearing, bending and rotating, and apply pressure constantly to fracture part. The present invention is suitable of fracture in tubular bones and is especially suitable for treatment of disconnected bone disease.

Jet/Intake Interference in Short Take off, Vertical Landing Aircraft

Abstract: An experimental programmewas conducted to investigate the aerodynamic interference effects between thejetand intake-induced e ows and the lifting surfaces of a generic jet-lift short take-off and vertical landing aircraft in transitional e ight, out of ground effect. The tests were carried out in an open-jet wind tunnel, and the model was equipped with a single, variable position, vectored lift-jet and powered intakes. Static pressure measurements were made on thewing and intakelips from which airloadswere inferred. Theeffect ofjet to intakemass e owratio on jet/intake aerodynamic interactions was investigated. The experiments conclude that a mutual interference exists between the jet and intake e ows, which generates nonlinearly additive loads on the airframe. The combined jet- and intake-induced interference on the wing increased with increasing jet to intake mass e ow ratio. Ignoring jet/intake interference effects gave a consistently lower overall wing root lift loss, which was equivalent to up to 0.75 deg of incidence. Nomenclature Ai = throat area of one intake [0.002], m 2 Cl = sectional lift coefe cient, fl=q1cg Cni = intake normal force coefe cient,

Unstructured Method for Flows past Bodies in General Three-Dimensional Relative Motion

Abstract: A three-dimensional methodology was developed for unsteady e ows past bodies that are in relative motion and where the trajectory of the motion was determined from the instantaneous aerodynamic e eld. This method coupled the equations of e uid e ow and those of rigid-body dynamics and then captured the unsteady aerodynamic interference between the stationary and moving boundaries. The time-dependent, compressible Euler equations weresolvedondynamic,unstructuredmeshesbyanexplicit,e nitevolume,andupwindmethod.Thegridadaptation was performed within a window placed around a moving body. The Euler equations of dynamics were then solved by a Runge‐Kutta integration scheme. The e ow solver and the adaptation scheme were validated by simulating the transonic, unsteady e ow around a wing undergoing a forced, periodic pitching motion and then comparing the results with the experimental data. Finally, the overall methodology was demonstrated by simulating the unsteady e owe eld and the trajectory of a store dropped from a wing. The methodology, with its computational cost notwithstanding, has proven to be accurate, automated, easy for dynamic gridding, and relatively efe cient for the required work hours. Nomenclature at

Center-of-gravity position-measuring device

Abstract: PROBLEM TO BE SOLVED: To improve measurement accuracy and reduce the number of tools by measuring the weight of a body to be measured in a pair of catch tools for supporting the body to be measured with a rotor while sandwiching the center of gravity of the body to be measured in the longitudinal direction of the body to be measured. SOLUTION: A catch tool 13 with a roller 12 as a rotor is mounted onto an electronic balance 4, and a wing root part W1a of a turbine wing (body to be measured) W1 is supported on the roller 12. On the other hand, a catch tool 15 with a roller 14 as a rotor is mounted onto an electronic balance 6, and a wing top part W1b of the turbine wing W1 is supported on the roller 14. Then, by measuring the weight of the turbine wing W1 in the catch tools 13 and 15 with the electronic balances 4 and 6, the center-of-gravity position of the turbine wing W1 is measured. In this case, since the wing root part W1a and the wing top part W1b are supported by the rollers 12 and 14, the friction of the contact part between the rollers 12 and 14 and the turbine wing W1 is reduced, thus eliminating offset for horizontally retaining the turbine wing W1 and for achieving stable measurement without any fluctuation.

Modal rotary-wing aircraft with foamed plastic rotary wings

Abstract: The utility model discloses a modal rotary-wing aircraft with foamed plastic rotary wings. A rotary wing blade is molded by rigid foam plastic. The wing root of the rotary wing blade is fixedly arranged around a rotary wing hub. The rotary wing blade is arranged from a position which is adjacent to the wing root to the direction of a blade middle part. A negative attack angle is converted into a positive attack angle. A main shaft of the rotary wing, wherein, the top of which extends out upwards is arranged on the upper part of a machine body of the modal rotary-wing aircraft. The rotary wings are assembled on the main shaft of the rotary wing. Air is driven by an engine or an electric motor. Thus, a propeller is rotated for offering dynamic force for advance. Thus, the modal rotary-wing aircraft can fly in the sky.