Jamel Bessrour - Profile on Academia.edu (original) (raw)

Papers by Jamel Bessrour

Journal of Engineering and Technology, Dec 31, 2009

In this paper, we are interested in the study of turbulent and time dependant flow inside a cylin... more In this paper, we are interested in the study of turbulent and time dependant flow inside a cylinder of an alternative engine through the investigation of the distribution of the turbulent kinetic energy in the whole space of the chamber. This research is carried out during the intake stroke. The arbitrary lagrangian eulerian technique coupled with the finite element method is used to solve the Navier Stokes equations. The turbulence model of the inlet air in the cylinder has a great influence in to the performance of the engine. It governs directly the rate of filling up, the thermal exchanges and the combustion quality. We present distribution of the velocity, pressure and turbulence field inside the engine room.

Journal of Mechanical Science and Technology, Nov 1, 2008

Taking into account the complexity and cost of a direct experimental approach, the recourse to si... more Taking into account the complexity and cost of a direct experimental approach, the recourse to simulation, which can also predict inaccessible information by measurement, offers an effective and fast alternative to apprehend the problem of pollutant emissions from internal combustion engines. An analytical model based on detailed chemical kinetics employed to calculate the pollutant emissions of a marine Diesel engine in general gave satisfactory results compared to experimentally measured results. Especially, the nitric oxide (NO) emission values were found to be higher than the limiting values tolerated by the International Maritime Organization (IMO). Thus, this study was undertaken to reduce to the maximum these emissions. The reduction of pollutant emissions is apprehended with exhaust gas recirculation (EGR).

Thermomechanical behavior of the piston of an aircooled diesel engine in semi-permanent mode

International Journal of Automotive Technology, Aug 2, 2016

The pistons of the diesel engines are currently used under increasingly high loadings. Crackings ... more The pistons of the diesel engines are currently used under increasingly high loadings. Crackings are sometimes observed without understanding their causes. This work is one of the studies contributing to the comprehension of the mechanisms at the origin of these problems and their modeling by the identification of the parameters which would make it possible to interpret the causes of these faulty operations. This study has permitted the development of a three-dimensional numerical simulation model of the coupled thermomechanical and dynamic behavior of an air cooled diesel engine piston. This study has particularly led to a realistic description, in semi-permanent mode, fields of temperatures, stresses and strains according to the mode and engine load and to identify the most solicited zones which constitute the zones at risk. The fatigue analysis of the endurance diagrams showed that the piston functions in the case of extreme loadings.

Tribology in industry, Dec 1, 2017

Numerical Exploration of the Hydraulics of a Front Axle Dual Tube Automobile Damper

Lecture notes in mechanical engineering, 2024

L'accroissement recherché de la température au niveau des distributeurs du premier étage d'une tu... more L'accroissement recherché de la température au niveau des distributeurs du premier étage d'une turbine à gaz a toujours été limité par la tenue mécanique des matériaux et par suite de durée de vie des organes. Dans la poursuite de cet objectif, les constructeurs associent l'utilisation de superalliages à des techniques de refroidissement. L'étude proposée constitue une contribution dans l'établissement d'une méthodologie et d'un modèle permettant d'identifier le comportement thermomécanique d'un secteur d'aubes refroidi par air, et d'associer ce comportement à un modèle paramétrique de résistance au fluage pour déterminer la durée de vie. Pour analyser ce problème et mettre en évidence les causes d'une défaillance constatée sur une turbine, nous avons identifié, en premier lieu, les paramètres réels d'exploitation de la machine. Le comportement thermomécanique du secteur d'aubes, sollicité par le chargement thermique dans les conditions d'exploitation est analysé à l'aide un code de calcul par éléments finis. Une modélisation des transferts de chaleur entre le gaz, l'aubage et l'air de refroidissement a permis de déterminer les coefficients de transfert au niveau des surfaces d'échange. L'état de contraintes thermiques identifié, associé aux températures locales, a permis de prédire une durée de vie, moyennant un modèle paramétrique de résistance au fluage.

Étude de la genèse des contraintes résiduelles lors de la trempe continue dans la masse de l'acier 36NiCrMo16

Matériaux et techniques, 2008

ABSTRACT This study concerns residual stress generated by bulk heat treatment of 36NiCrMo16 steel... more ABSTRACT This study concerns residual stress generated by bulk heat treatment of 36NiCrMo16 steel french grade. The aim of this study is to develop a model for prediction of the residual stresses state generated by quenching. The resolution of this problem requires the development of two numeric simulation models, using a standard FEM code. The first is a non-linear transient model allowing simulating of space-time distribution of temperature from the austenitic temperature to the cooling temperature. The latter is a non-linear transient model allowing the mechanical behaviour simulation of the specimen introducing his thermal history during cooling as loading. We propose the definition of a global expansion coefficient to take into account the simultaneous and cumulated thermal and martensitic transformation strains. Mechanical features and thermophysics properties are described in space-time evolutions depending on the temperature and the present phases. Simulated residual stresses evolution are compared with stresses measured by hole-drilling method and by X-ray diffraction. Cette étude concerne la modélisation de la genèse des contraintes résiduelles induites par la trempe continue dans la masse de l'acier faiblement allié de nuance 36NiCrMo16. La résolution de ce problème a nécessité le développement, par le biais d'un code de calcul par éléments finis, de deux modèles de simulation numérique. Le premier concerne un modèle thermique non linéaire non stationnaire, qui permet de simuler la distribution spatio-temporelle de la température tout au long du traitement. Le deuxième est également un modèle non linéaire non stationnaire qui permet la simulation du comportement mécanique de l'éprouvette en introduisant son histoire thermique comme chargement. Nous proposons la définition d'un coefficient appelé coefficient dilatométrique global qui tient compte, dans une formulation macroscopique, de la dilatation thermique et des déformations volumique liées à la transformation de phase. Ce coefficient est pris en compte dans le code de calcul pour un calcul en thermo-élasto-plasticité. Les caractéristiques thermiques et mécaniques sont décrites par des évolutions spatio-temporelles dépendant de la température et des phases présentes. Les évolutions des contraintes résiduelles obtenues par simulation numérique sont comparées à celles déterminées par la méthode du trou incrémental et par diffraction des rayons X pour des éprouvettes, réalisées dans la même nuance d'acier, trempées dans différents milieux.

Advances in Building Energy Research, Sep 3, 2019

The success or failure of river closure is directly related to the construction period and projec... more The success or failure of river closure is directly related to the construction period and project benefit. Therefore, it is very necessary to study the river closure by an appropriate method. In this paper, a 1D-2D coupled river closure model is established to optimize the closure flow rate, closure period, and layout of a real closure project. The 1D transition model between open channel flow and pressurized flow is established by a finite volume scheme. For the 2D model, 2D shallow water equations are solved using an unstructured finite volume scheme. The 1D model and 2D model are coupled by considering the mass and momentum conservation. To validate the model, a physical experiment of a real river closure project is set up according to the gravity similarity criterion with a scale of 1:80. Then, the experimental data obtained by the calibrated physical experiment is compared with the numerical results. Good agreements are achieved in terms of surface elevation, velocity, and flow rate. Finally, the real river closure project is further investigated by the model. The layout, closure flow rate and closure period of this project is analyzed and optimized. The original design of the berm is more suitable to discharge the flow. Moreover, the first stage cofferdam should be removed to floor elevation upstream and downstream of the dam. The river closure flow rate should not exceed 2380 m 3 /s.

Mécanique & industries, May 1, 2008

Une analyse numérique du processus d'évolution de l'écoulement dans le plan axial d'un cylindre d... more Une analyse numérique du processus d'évolution de l'écoulement dans le plan axial d'un cylindre d'un moteur à deux soupapes et quatre temps pendant la course d'admission est effectuée en utilisant une méthode d'éléments-finis pour un problème à frontières mobiles. Le domaine de calcul, à géométrie variable, inclut simultanément le conduit d'admission, la région de la soupape et la chambre de combustion. Le mouvement des interfaces entre le fluide, le piston et la soupape a été considéré. La méthode Lagrangienne Eulérienne Arbitraire (ALE) a été utilisée pour décrire les champs aérodynamique et thermique. Deux modèles d'interpolation des vitesses de maillage ont été adoptés : l'un est rattaché au mouvement du piston et l'autre à celui de la soupape. Le processus d'évolution et d'établissement des diverses structures tourbillonnaires et du champ thermique dans le plan axial du cylindre, caractérisé par une chambre hémisphérique et des soupapes latérales, est présenté. Cette étude a montré que la modélisation adoptée conduit à une simulation numérique avec une précision raisonnable en comparaison avec les résultats expérimentaux publiés récemment.

Experimental Modeling and Multi-Response Optimization in Friction Stir Welding Process Parameters of AA2024-T3 Using Response Surface Methodology and Desirability Approach

Experimental techniques, Jan 30, 2024

International Journal of Low-Carbon Technologies

This research aims to study the effect of various blends of an alternative fuel environment (etha... more This research aims to study the effect of various blends of an alternative fuel environment (ethanol, isooctane) on the performance of a spark ignition gasoline engine. The blends were obtained from two additives: ethanol and isooctane. The tests were carried out on an engine test bench following DIN 70020. The results show that the petrol additives achieve excellent ecological results. On the other hand, the engine performance was slightly reduced compared with that obtained with pure fuel. We noted a variation in engine performance for the E10 (10% ethanol + 90% pure petrol) and I10 (10% isooctane + 90% pure petrol) blends, namely a reduction in nitrogen oxides (NOx) emissions of 7.5% for E10 and 5% for I10 compared with pure petrol. However, using E10 and I10 blends did not increase the specific fuel consumption. Thus, the increase in the octane rating resulted in a decrease in NOx emissions. The use of 96 octane fuels, which corresponds to I40 (40% isooctane + 60% petrol), is ex...

An improved time-dependent Boundary Element Method for two-dimensional acoustic problems in a subsonic uniform flow

Journal of Computational Science, Jul 1, 2017

Abstract In this paper, we have developed an improved formulation of two-dimensional Convected Bo... more Abstract In this paper, we have developed an improved formulation of two-dimensional Convected Boundary Element Method (CBEM) for radiation and propagation acoustic problems in a uniform mean flow with arbitrary orientation. The improved CBEM approach is derived from an advanced form of time-space two-dimensional Boundary Integral Equation (BIE) according to new Sommerfeld Radiation Conditions (SRC) with arbitrary mean flow. The acoustic variables of these formulations are expressed only in terms of the acoustic field as well as its normal and tangential derivatives. The multiplication operators are based explicitly on the two-dimensional Green's function and its convected normal derivative kernel. The proposed terms significantly reduce the presence of flow quantities incorporated in the classical integral formulations. Precisely, the convected kernel only requires the evaluation of two terms instead of several terms in conventional formulations due to the flow effects in the temporal and spatial derivatives. Also, for the singular integrations, the kernels containing logarithmic and weak singularities are converted to regular forms and evaluated partially analytically and numerically. The formulation is derived to be easy to implement as a numerical tool for computational codes of acoustic mediums with arbitrary mean flow. The accuracy and robustness of this technique is assessed through several examples such as the two-dimensional monopole, dipole and quadrupole sources in a uniform mean flow. An application of the improved formulation coupled with Particular Dirichlet-to-Neumann operators (PDtN) has been presented to describe the acoustic field inside two-dimensional infinite ducts in a uniform mean flow. The numerical results are compared to analytical, conventional BEM and Finite Element Method (FEM) formulations.

International Journal of Aeroacoustics, Dec 15, 2020

This paper presents a new numerical analysis approach based on an improved Modal Boundary Element... more This paper presents a new numerical analysis approach based on an improved Modal Boundary Element Method (MBEM) formulation for axisymmetric acoustic radiation and propagation problems in a uniform mean flow of arbitrary direction. It is based on the homogeneous Modal Convected Helmholtz Equation (MCHE) and its convected Green's kernel using a Fourier transform method. In order to simplify the flow terms, a general modal boundary integral solution is formulated explicitly according to two new operators such as the particular and convected kernels. Through the use of modified operators, the improved MBEM approach with flow takes a convective form of the general MBEM approach and has a similar form of the nonflow MBEM formulation. The reference and reduced Helmholtz Integral Equations (HIEs) are implicitly taken into account a new nonreflecting Sommerfeld condition to solve far field axisymmetric regions in a uniform mean flow. For isolating the singular integrations, the modal convected Green's kernel and its modified normal derivative are performed partly analytically in terms of Laplace coefficients and partly numerically in terms of Fourier coefficients. These coefficients are computed by recursion schemes and Gauss-Legendre quadrature standard formulae. Specifically, standard forms of the free term and its convected angle resulting from the singular integrals can be expressed only in terms of real angles in meridian plane. To demonstrate the application of the improved MBEM formulation, three exterior acoustic case studies are considered. These verification cases are based on new analytic formulations for axisymmetric acoustic sources, such as axisymmetric monopole, axial and radial dipole sources in the presence of an arbitrary uniform mean flow. Directivity plots obtained using the proposed technique are compared with the analytical results.

An application of Boundary Element Method to two-dimensional infinite lined duct without flow

The paper presents the Boundary Element Method formulation (BEM) applied to determine the acousti... more The paper presents the Boundary Element Method formulation (BEM) applied to determine the acoustic field in a two-dimensional infinite lined duct without flow. The proposed method is derived from the Homogeneous Helmholtz Equation (HHE) and its fundamental solution of the monopole acoustic source. In addition, when the source point is taken at the boundary point, a regular method is used to isolate the singular integrals of the two-dimensional Green's kernel and its normal derivative. A validation of the present approach was done by a comparison with the analytical formulation for two-dimensional lined duct in which the artificial boundaries contain the conditions of the Dirichlet-to-Neumann (DTN).

International Journal of Physical Sciences, Mar 31, 2008

We are interested in the study of turbulent and instationary flow inside a cylinder of an alterna... more We are interested in the study of turbulent and instationary flow inside a cylinder of an alternative engine. The finite element method is used to solve equations model. As the domain of the flow is changing with time due to the moving piston, an arbitrary Lagrange eulerian technique is chosen to reply to this problem. The modelisation is based on classic k-model. In this paper, we will present instantaneous velocity, streamlines and temperature maps obtained at various crank angles. We validate our results with other numerical predictions.

Advances in Mechanical Engineering, 2009

Journal of Materials Processing Technology, Jun 1, 2010

In this paper, a three-dimensional finite element model is developed to simulate thermal history ... more In this paper, a three-dimensional finite element model is developed to simulate thermal history magnesium-based alloys during laser beam welding. Space-time temperature distributions in weldments are predicted from the beginning of welding to the final cooling. The finite element calculations were performed using Cast3M code with which the heat equation is solved considering a non-linear transient behaviour. The applied loading is a moving heat source that depends on process parameters such as power density, laser beam dimensions and welding speed, and it is associated to moving boundary conditions. Experiments were carried out to determine temperature evolution during welding and to measure the laser weld width. By comparing the thermal model answers with the measurements, it is found that numerical simulations results are in a good agreement with the experimental data.

International Journal of Technology

Welding is widely used in the aerospace, naval and automotive industries. Since high temperatures... more Welding is widely used in the aerospace, naval and automotive industries. Since high temperatures are involved in this process, solid state metallurgical changes are expected. These metallurgical changes can induce deformations and residual stresses in welded parts. The objective of this work is to develop a finite element calculation code, under the MATLAB environment, to predict the evolution of the various metallurgical transformations during TIG welding of C50 steel plates. In the proposed calculation procedure, we used Leblond's equation and Waeckel's model to characterize the metallurgical transformations during respectively heating and cooling stage. We also taken into account the effect of austenitic grain size on metallurgical transformations evolution. Thermal properties are introduced according temperature and phase proportions present during welding operation. Simulation results show that the metallurgical structure in the heat affected zone (HAZ) is largely related to welding thermal power and the plate preheating temperature. We compared simulation results to experimental measurements and the efficiency of the developed computational code was confirmed.

Physical Science International Journal

Taking into account the interaction between the engine oil and the crankshaft to model crankshaft... more Taking into account the interaction between the engine oil and the crankshaft to model crankshaft thermomechanical behavior under dynamic loading is very important. In particular, when the crankshaft is working in severe conditions. This paper deal with an air cooled direct injection-type engine crankshaft thermomechanical FEM modelling account for engine oil-cranks half interaction in severe working conditions. As case of application we consider the diesel engine Deutz F8L413. The model takes into account 2 forced convectives heat flux: engine oil and crankcase air. The severe mechanical and thermal characteristics of engine are experimentally measured on a bench test equipped with a hydraulic brake. The temperature distribution inside the crankshaft was computed using the measured temperature as boundary conditions. The most thermo-mechanical stressed zones of the crankshaft have been determined. The fatigue resistance of the crankshaft under thermo-mechanical conditions was exami...

Microstructure and Mechanical Properties of Friction Stir Welded AA2024-T3 Joints

This paper focuses on the examination of macrostructure and microstructure of friction–stir-welde... more This paper focuses on the examination of macrostructure and microstructure of friction–stir-welded AA2024-T3 joints. The tool rotation speed and the traverse speed, the most important process parameters of FSW, are evaluated through tensile strength test and microhardness test. The analysis of microstructure showed a zonal transition from the base material to a heat-affected zone; a thermo-mechanical affected zone and a nugget zone in the center of the weld with a grain sizes were different. From this investigation, it is found that the tensile strength and percentage elongation increase with the traverse speed decreasing, whereas it increases as tool rotation speed increases up to the 750 rpm and then decreases with further increase of tool rotation speed. As a result, increasing the tool rotational speed leads to the increase in hardness nugget zone than that in the thermo-mechanically affected zone and affected zone. The microhardness was strongly dependant on tool rotation speed...