Influence of Flap Angle on the Aeroelastic Behavior of Wing- Flap Configuration Using Fully Coupled Structure-Fluid Interaction Model

The influence of trailing edge flap angle on the aeroelastic behavior of a vibrating wing-flap configuration is investigated in this work. For this purpose an aeroelastic numerical model with fully coupled structure-fluid interaction is developed. The flow and structural solvers are coupled via successive iterations within each physical time step. The aerodynamic model is based on a hybrid unsteady panel method which is still a good approach to calculate the unsteady loads. While the nonlinear plate equation solved by an assumed mode method is used to represent the structure wing model. The results for a vibrating rectangular wing-flap configuration in low subsonic attached flow are presented, including the effect of flap angle on the unsteady pressure coefficient, time history of lifting coefficient and aeroelastic behavior of the wing. These results clearly show the effect of strong structure-fluid interaction and illustrate the utility of the present model which may be used in the preliminary stage of the wing design

Flutter Estimation for Low Speed Aircraft Wing Using Fully Coupled Fluid – Structure Interaction

The aero elastic responses and the flutter condition of 3-D flexible aircraft wing were estimated by developed fully coupled fluid-structure interaction approach. The actual wing in this approach was represented by an equivalent plate .Equivalent plate model (structure model) based on assumed mode method was then combined with unsteady panel-discrete vortex method (aerodynamic model) to build relatively simple aeroelastic model. This model could be used for estimation of flutter condition of moderate to high aspect ratio and low sweep wings of aircraft flight at low subsonic speeds. The obtained results from the present model are able to prediction the flutter condition of the actual wing at different angles of attack. The increasing in the angle of attack leads to reduce flutter speed and flutter frequency

Control on 3-D Fixable Wing Flutter Using an Adaptive Neural Controller

An adaptive neural controller to control on flutter in 3-D flexible wing is proposed. The aeroelastic model was based on the coupling between structure-of the equivalent plate (wing) and the aerodynamic model that is based on a hybrid unsteady panel methodTime domain simulations were used to examine the dynamic aeroelastic instabilities of the system (e.g. the onset of flutter and limit cycle oscillation). The structure of the controller consists of two models namely modified Elman neural network (MENN) and feedforward multi-layer Perceptron (MLP). The MENN model is trained with off-line and on-line stages to guarantee that the outputs of the model accurately represent the plunge motion of the wing and this neural model acts as the identifier. The feedforward neural controller is trained off-line and adaptive weights are implemented on-line to find the generalized control action (function of addition lift force), which controls the plunge motion of the wing. The general back propagation algorithm is used to learn the feedforward neural controller and the neural identifier. The simulation results show the effectiveness of the proposed control algorithm; this is demonstrated by the minimized tracking error to zero approximation with very acceptable settling time

Towards high-valent nickel complexes and their involvement in aromatic fluorination

Dans le paysage complexe de l'innovation industrielle, les composés organofluorés sont des éléments indispensables dans les domaines de la pharmacie, de l'agrochimie et des matériaux avancés. Cependant, la recherche permanente de méthodologies durables et efficaces pour l'introduction d'atomes de fluor et de groupes trifluorométhyles dans les molécules organiques est devenue de plus en plus impérative, puisque les processus industriels actuels sont ancrés dans des méthodologies obsolètes qui sont questionnables en termes de durabilité environnementale. Pour relever ces défis, les complexes de nickel à haute valence sont apparus comme des catalyseurs prometteurs, offrant des nouvelles voies potentielles vers des processus de fluoration et de trifluorométhylation. Malgré leur potentiel, la stabilisation et le déploiement pratique de ces espèces de nickel à valence élevée restent des défis considérables dans le domaine de la chimie organométallique. Cette Thèse de Doctorat cherche donc à relever ces défis en explorant la stabilisation des espèces de nickel à haute valence par l'utilisation stratégique de ligands simples et facilement accessibles en conjonction avec un métallacycle perfluoré, facilitant ainsi une étude approfondie de leur réactivité.Ces travaux de recherche ont amené la découverte d’une nouvelle série de précurseurs monomères et dimères de nickel(II), stabilisés par une unité chélatante perfluoroalkyle [C4F8] et soutenus par des ligands facilement accessibles. Ces complexes comprenant des dimères dianioniques de nickel pontés par divers halogénures et des espèces monomériques aryle-nickel, fournissent les bases pour la génération de complexes de nickel à haute valence, ciblant principalement l'état d'oxydation +IV. Bien que l'isolement et la caractérisation complète de ces espèces à haute valence se soient avérés difficiles, l'étude a fourni des aperçus critiques sur leur réactivité. Notamment, ces espèces de nickel ont montré un potentiel significatif vis-à-vis de la fluoration aromatique, une transformation d'importance majeur dans la synthèse de composés organofluorés.Les connaissances acquises dans le cadre de ce travail constituent une base solide pour les recherches futures visant à offrir de nouvelles perspectives sur la stabilisation et la réactivité de ces entités complexes. Elles ouvrent également une voie à l’exploration du potentiel catalytique des espèces de nickel à valence inhabituelle élevée, ce qui permettra de faire progresser les méthodologies synthétiques innovantes qui s'alignent sur les exigences évolutives de la chimie moderne.In the complex landscape of industrial innovation, organofluorine compounds stand as indispensable elements within the realms of pharmaceuticals, agrochemicals, and advanced materials. However, the ongoing pursuit of sustainable and efficient methodologies for the introduction of fluorine atoms and trifluoromethyl groups onto organic molecules has grown increasingly imperative, as current industrial processes are anchored in antiquated methodologies that are questionable in terms of environmental sustainability. Addressing these challenges, high-valent nickel complexes have emerged as promising catalysts, offering potential pathways to fluorination and trifluoromethylation processes. Despite their potential, the stabilization and practical deployment of these high-valent nickel species remain formidable challenges within organometallic chemistry. Thus, this Ph.D. Thesis seeks to confront these challenges by exploring the stabilization of high-valent nickel species through the strategic use of simple and readily accessible ligands in conjunction with a perfluorinated metallacycle, thereby facilitating a thorough investigation into their reactivity.This research introduces a novel series of monomeric and dimeric nickel(II) precursors, stabilized by a chelating perfluoroalkyl unit [C4F8] and additionally supported by easily accessible ligands. These complexes ─including dianionic nickel dimers bridged by various halides and monomeric species bearing an aromatic moiety─ provide the groundwork for the generation of high-valent nickel complexes, mainly targeting the nickel(IV) oxidation state. Although the isolation and comprehensive characterization of these high-valent species have proven challenging, the study has provided critical insights into their reactivity. Notably, these nickel species have shown significant potential in aromatic fluorination, a transformation of major relevance in the synthesis of organofluorine compounds.The insights garnered through this work lay a robust foundation for future research aimed at offering new perspectives on the stabilization and reactivity of these complex entities while fully harnessing the catalytic potential of high-valent nickel species, thereby advancing innovative synthetic methodologies that align with the evolving demands of modern chemistry