Génie mécanique
Numerical study of air preheating effect on NOx emissions in a heating furnace
This work aims to evaluate the reduce pollutant emission by steel reheating furnaces and operating process of the diffusion flame industrials burners. The example developed here is particularly interested in the influence of the air preheating temperature on NOx emissions as well as the dynamic characteristics and heat flow. The study was conducted on an industrial gas burners 250kilowatt. Numerical simulations are per formed using the computer code FLUENT, using the turbulence standard k-ε model coupled to turbulent combustion ED (Eddy Dissipation). The probability density function PDF model (6 species and reactions 3) with a chemical equilibrium model. The results obtained for different air preheat temperatures show that NOx emissions depend on the air preheat temperature. Voir les détails
Mots clés : pollutant emission, industrials burners, turbulent combustion
An experimental analysis of fracture mechanisms by acousticemission of woven composite bolted assembly
This work is focused on the study of the evolution of damage mode and failure mechanisms of woven composite bolted assembly carbon fiber/epoxy. In the present paper three configurations are studied [0°,45°,0°,45°], [0°,45°,0°,45°]s and [0°,45°,0°,45,0°]s. In order to analyze a global mechanical behavior of the assembly, monotonous tensile tests are performed. The damage evolution is followed simultaneously by acoustic emission (A.E) and digital image correlation (D.I.C). Acoustic signatures of four modes of damage are identified, matrix cracking, fiber-matrix debonding, delaminating and fiber breakage, then confirmed by microscopic observations in scanning electron microscopy (SEM).Composite woven, émission acoustique, assemblage boulonné, corrélation d'image numérique, endommagement. Voir les détails
Mots clés : Woven composite, acoustic emission, bolted assembly, digital image correlation, Damage.
A Comparative Study of Various Methods of Bearing Faults Diagnosis Using the Case Western Reserve University Data
Bearing is probably one of the most critical components of rotating machinery. They are employed to guide and support the shafts in rotating machinery. Therefore, any fault in the bearings can lead to losses on the level of production and equipments as well as potentially unsafe. For these reasons, the bearing fault diagnosis has received considerable attention from the research and engineering communities in recent years. The purpose of this study is to review the vibration analysis techniques and to explore their capabilities, advantages, and disadvantage in monitoring rolling element bearings. Voir les détails
Mots clés : Vibration analysis, bearing Fault diagnosis, Temporal analysis, Cepstrum analysis, Envelope analysis, Wavelet transform
Numerical Simulation of Temperature Distribution and Material Flow During Friction Stir Welding 2017A Aluminum Alloys.
Abstract.This study describes the use of fluid dynamic code, FLUENT to model the flow of metal in the AA2017A case around the welding tool pin (FSW). A standard threaded tool profile is used for the analysis of phenomena during welding such as heat generation and flow of the material are included. The main objective is to gain a better understanding of the flow of material around a tool. The model showed a large number of phenomena similar to those of the real process. The model has also generated a sufficient amount of heat, which leads to a good estimate of the junction temperature. These results were obtained using a viscosity which is near the solidus softening. Voir les détails
Mots clés : Friction Stir Welding, 2017A aluminum alloy, Temperature distribution
Finite volume modeling of laser assisted friction stir welding of 2017A-T451 aluminum alloy for enhanced sustainability of welded joints.
This study focuses on a new welding modification friction stir welding, using a preheating during the welding phase. This method utilizes laser energy to pre-heat the workpiece to a localized area at the front of the FSW tool, thereby reducing the temperature gradient over a localized area in advance of the tool. The amount of heat generated during welding determines the quality of the weld. Therefore the understanding of the temperature distribution is required to determine the optimal method of welding parameters. In this study, a two-dimensional model of an aluminum alloy plate coupled to a circular laser source is developed, using FLUENT software that is based on the finite volume method, also the geometry of the pin of the FSW tool was modified in several configurations to highlight the effect of the geometry of the tool on the temperature distribution in the welded plate. The model developed can be used to better understand the process, predict process performance and to determine the optimal parameters of the process. Voir les détails
Mots clés : riction stir welding, 2017A-T451 aluminum alloy, Finite volume modeling
Numerical and Experimental Investigation of FluidicMicrodrops Manipulation by Fluidic Mono-Stable Oscillator
A numerical and experimental study of passive microdrops manipulation hasbeen presented. This paper focuses on the modeling of micro-oscillators systemswhich are composed by passive amplifier without moving part. The characteristicsize of the channels is generally about 35 ¹mof depth. The numerical results indicatethat the production and manipulation of microdrops are possible with passivedevice within a typical oscillators chamber of 2:25 mm diameter and 0:20 mmlength when the Reynolds number is Re = 490. The novel microdrops methodthat is presented in this study provides a simple solution about the production ofmicrodrops problems in micro system. We undertake an experimental step. Thefirst part is based on realization of sample oscillator; the second part is consistedof visualization of the microdrops production and its manipulation. Voir les détails
Mots clés : microdrop, fluidic oscillator, CFD
Numerical Investigation of Flow Dynamic in Mini- Channel: Case of a Mini Diode Tesla
Microfluidic systems are used and exploited in various fields, as they are highly specific and developed in their use. The micro devices are used in various analyzes of medical disciplines, chemical and other fields. Our research team "MAAt" within ENERGARID laboratory is in the process of triggered several lines of research in this area, the micro-mixing, separation of micro particles, droplet production. For that, we need tools and micro devices to study the phenomena.. In this work, we present a theoretical study and numerical simulation of micro device (micro diode Tesla). A Diode Tesla is similar to a heart valve conduit profile is shown in the following figure: In this simulation work, we will focuse the variation of geometrical parameters, the inside length lw (lw1> lw2> lw3), this study aims to optimize this setting to get a better efficiency. Then we will investigate the effect of the pressure variation on the volume flow. Voir les détails
Mots clés : Mini channel, diode Tesla, Efficiency, gas flow, microsystem.
Effects of a circular defect size and position on the damage progression in hybrid laminates under compressive loading
The effects of a circular defect size and position on the post-damage response of the FMLs laminates under compressive loading have been studied. Compression tests are performed on composite plates comprising a hole having different diameters (8 mm, 12 mm and 18 mm) and located at different positions (25%, 50% and 75%) in the loading direction. A numerical analysis using the finite element method FEM has permits the identification of the initiation zones and the description of the damage evolution in these laminates. The results of the numerical simulation are in good agreement with the experimental results. The FEM has well predicted the critical damage zones Voir les détails
Mots clés : FMLs laminates, damage progression, compressive loading, finite element
Caractérisation thermique et tribologique des composites thermostructuraux C-C et composite à matrice organique
Le comportement tribologique sec des couples acier-composite thermostructuraux carbone-carbone et acier-composite à matrice organique et les phénomènes dû aux frottements sont étudiés. En utilisant un modèle mathématique, la température superficielle du contact a été déterminée. Les résultats illustrent l’évolution de la température en fonction du temps. La charge normale, la vitesse de glissement et le coefficient de frottement ont une influence significative sur la variation de la température Voir les détails
Mots clés : température, frottement, acier, composite, disque, garniture
Modeling of temperature field at outlet of continuous casting mold
Continuous casting of steel is a complex industrial process, involving many factors and mechanisms. For steel makers it is very difficult to control the process parameters optimally to obtain a product free defect i.e. a quality with the best possible return. Numerical simulation is a tool that can be used to optimise the process parameters. This work has for objective to model the temperature field at the level of solidified skin at the outlet of the mold "Ts". There are , three important key parameters affecting the cooling process in the mold: The "immersion distance of the nozzle Di", the "casting temperature Tc" and the "casting speed Vc". Thes parameters are used as input parameters during a parametric study by the experiments: "box behenken" Plans. The "outlet temperature Ts" is measured on the consolidated layer of steel on leaving the mold. The simulation of continuous casting phenomen is carried out by the Fluent code 6.0. A relation between the above cited key parameters and the "outlet temperature Ts," was established by using the required algorithm. Thus, the optimal parameters were obtained by predicting a minimum threshold temperature (TSmin) at the outlet of the mold. Voir les détails
Mots clés : continuous casting, output tempetature, casting temperature, casting speed, distance immersion, model "box behenken."