Showing papers in "Aerospace Science and Technology in 1997"

TL;DR: In this article, a measure of the extra influence on the turbulence which is invariant, fully defined in three dimensions, and unifies rotation and curvature effects is proposed, at the expense of involving higher derivatives than the traditional (non-invariant) terms do.

TL;DR: In this paper, the damaged elastic properties of composite materials are modeled in the framework of Continuum Damage Mechanics, which combines different types of variables in describing the damage state of the material.

TL;DR: In this paper, a nonlinear model of the mechanics of the landing gear and tire elasticity according to elastic string theory is applied to the shimmy analysis of a simple model of a nose gear: computing eigenvalues, solving analytically the stability boundaries with a parameter space method, and last but not least numerical simulation of time histories.

TL;DR: The Environmental effects issue of air traffic has been gaining increasing public attention as mentioned in this paper, which has led to a considerable world-wide effort to reduce aircraft emissions, including a broad variety of scientific and technological problems which are reviewed.

TL;DR: In this paper, the dynamics during the jet regime of the wake of a subsonic aircraft cruising in a stably stratified and turbulent atmosphere is simulated by means of a vortex-filament technique and large-eddy simulations.

TL;DR: In this article, the authors highlight different aspects of engine-airframe integration and summarizes areas of concern for engine installation such as, engine development trends, turbofan integration with respect to advanced engine concepts, programmes and investigations on propeller integration, application of theoretical methods in particular, engine location, nacelle design and flow aspects as well as jet flows.

TL;DR: In this paper, the authors present a simple analytical solution for computing bifurcation buckling loads of thin and moderately thick orthotropic cylindrical shells and panels subjected to axial compression and normal pressure.

TL;DR: In this article, a simple method is given for the evaluation of the induced lift, which is defined as the lift due to the velocities that the lifting vortices induce on themselves.

TL;DR: In this article, an experimental study of swept wing leading edge contamination by the turbulence emanating from the wing-wall junction is devoted to delay the contamination onset by applying surface suction along the attachment line.

TL;DR: In this article, the ONERA models are compared with the model developed by the LMT-Cachan, and the purpose of the present paper is to compare these models on a set of experimental data obtained on CMCs.

TL;DR: The natural damped frequencies of a viscous liquid in a circular cylindrical container are obtained for slipping and anchored contact line at the container wall r = a in this paper, and the response to translational forced excitation has been determined.

TL;DR: In this paper, an experimental contribution to the investigation of the wing rock phenomenon is presented, where free-to-roll experiments and flow visualizations were performed on a 80° delta wing, at different subsonic airspeeds and angles of attack.

TL;DR: In particular, l'interpretation a donner aux grandeurs moyennes et turbulentes obtenues par cette methode est discutee as discussed by the authors, and les consequences sur la validite de la methode de ''moyennes de phasea habituellement utilisee lors de mesures ponctuelles (par exemple, anemometrie laser Doppler (LDA), pressions parietales, fils chauds) pour etudier des ecoulements instationnaires supposes period

TL;DR: In this article, a new model is proposed for the two-point correlation spectrum tensor in which the directional properties of the turbulent field can be considered in terms of the specific structural anisotropy tensor.

TL;DR: In this article, basic data were obtained for the code predicting of Novoltex type material ablation at the nozzle throat for large solid rocket motors, which concerned the variation of the ablation rate as a function of the material surface temperature, and the assessment of the convective heat transfer coefficient for physical-chemical interface conditions representative of actual ablation conditions for the full scale nozzle throat.

TL;DR: In this paper, the authors compared the blade element method, a panel method and an Euler method for the aerodynamic design and the panel method was chosen for the aero-acoustic calculation.

TL;DR: In this paper, a target tracking method is proposed that directly associates and filters identity likelihoods built on such features, in the framework of theory of evidence, which offers a number of advantages deriving from the fact that it avoids local detection decisions; makes synergetic use of the classification and tracking functions; provides integrated, adapted processing of ambiguities when matching multiple observation; manages target signature uncertainties appropriately; and provides a suitable track validation procedure.

TL;DR: This paper proposes to list the various features which may be extracted from the sensors generally used in a ground-air defence context and which can be exploited for the classification and deals with two categories of methods, namely: the Bayesian method and fuzzy classification methods.

TL;DR: In this paper, the structure of a supersonic hot jet at Mach 1.8 injected into a coaxial supercarrier with axisymmetric flow was analyzed by differential interferometry, the total pressure ratio being a variable parameter.

TL;DR: In this article, a finite difference method for the simultaneous measurement of the three-dimensional velocity vector and its gradient tensor in turbulent airflow is presented and verified, which relies upon the simultaneous measurements of the velocity vector at different locations of the flow field using a twenty-hotwire probe consisting of five orthogonal fourhotwire subprobes.

TL;DR: In this article, the performance of several different numerical methods using the von Neumann method for the compressible Euler Equations was investigated and the results were used to analytically estimate the error due to the numerical schemes with an approximate spectrum of the turbulence obtained from isotropic homogeneous turbulence theory.

TL;DR: In this article, the problem of motion of a rigid body about a fixed point under the action of a Newtonian force field is studied when the natural frequency value w = 1 3.

TL;DR: In this article, the authors used the vortex method to calculate the air flow around a helicopter rotor in hover using data on initial wake geometry and aerodynamic characteristics, the latter being obtained by bidimensional wind tunnel tests.

TL;DR: In this article, the convection velocities are estimated from mean measurements available in the literature, applied to a simple turbulent diffusivity model and to a scheme of shocks attached to eddies.

TL;DR: In this article, a 3D multi-injector combustion chamber and the flowfield computation of a plug nozzle concept are presented for high performance thrust chamber simulations of a rocket engine, where propellants are burned at high pressures to achieve a maximum performance.

TL;DR: In this article, a micro-crack damage model based on a constitutive theory for brittle materials weakened by microcracks is proposed, which is implemented in the DYNA3D three-dimensional explicit finite element code.

TL;DR: In this article, a nouvelle methode de decomposition de domaines is proposed, basee sur le couplage des techniques euleriennes et lagrangiennes appliquees aux equations de Navier-Stokes ecrites en formulation vitesse-tourbillon.

TL;DR: In this paper, a method of calculation concerning waves radiated by an oscillating surface-piercing flat plate with forward speed, with a yaw angle, was presented.

TL;DR: In this article, a new concept called the Modal Force Combination (MFC) technique is presented, which replaces the base acceleration commonly applied during structural dynamic qualification by having a set of forces act directly in a selected number of structural points.

TL;DR: In this article, the common bulkhead of the Ariane 5 tank structure has been submitted to detailed finite element analyses by means of the finite element code ABAQUS for verification and verification.