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

Papers by Jamel Bessrour

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...

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.

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

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).

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...

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...

International Journal of Aeroacoustics, 2020

This paper presents the CFD study of the aerodynamic structure in an indoor environment occupied ... more This paper presents the CFD study of the aerodynamic structure in an indoor environment occupied by a human body. Reynolds Averaged Navier-Stokes equations were used and different turbulence models were evaluated such as the RNG k-ε turbulence model, the standard k-ε turbulence model, the standard k-ω turbulence model and the SST k-ω turbulence model. The results of our simulations developed using the software ''ANSYS Fluent 17.0'' were compared with findings from anterior experimental measurements. This comparison affirms that the turbulence model has a direct effect on the aerodynamic structure in an indoor environment. In fact, the SST k-ω turbulence model presents a good agreement with the anterior study and it is recommended for the related type of application. These numerical results highlight a thermal plume above the human body due to the convection heat transfer. Finally, indoor thermal comfort analyses are conducted at varying supply velocity

2016 4th International Conference on Control Engineering & Information Technology (CEIT), 2016

The International Journal of Advanced Manufacturing Technology, 2017

The main goal of this study is the modeling of ultimate tensile strength produced by friction sti... more The main goal of this study is the modeling of ultimate tensile strength produced by friction stir welding of AA2024-T3 aluminum alloy using Taguchi and surface response methodologies. The considered process parameters are tool rotation speed, tool traverse speed, and wiper™ tool geometry (shoulder diameter). Analysis of variance, signal to noise ratio, and main effects plot used to check which process parameters were statistically significant and have better quality characteristics. Linear regression model was used to predict the ultimate tensile strength of the welded joints by incorporating process parameters. By using sensitivity analysis, the effectiveness of process parameters and the most significant parameter have been shown. From this research, the optimal experimental condition which gives the maximum ultimate tensile strength was obtained with a tool rotation speed of 750 rpm, a tool traverse speed of 100 mm/min, and a tool shoulder diameter of 12 mm which is 84% of joint efficiency of the base metal. The ultimate tensile strength increased to a maximum value and could be decreased with increasing tool rotation speed. Moreover, increasing the tool traverse speed or the tool shoulder diameter also make it decreased. Microscopic analysis showed that the increasing of the tool rotation speed or tool shoulder diameter results in an increase of average grain size in the nugget zone while it decreased slightly as tool traverse speed increases.

Theoretical and Applied Mechanics Letters, 2017

To reduce computational costs, an improved form of the frequency domain boundary element method (... more To reduce computational costs, an improved form of the frequency domain boundary element method (BEM) is proposed for two-dimensional radiation and propagation acoustic problems in a subsonic uniform flow with arbitrary orientation. The boundary integral equation (BIE) representation solves the two-dimensional convected Helmholtz equation (CHE) and its fundamental solution, which must satisfy a new Sommerfeld radiation condition (SRC) in the physical space. In order to facilitate conventional formulations, the variables of the advanced form are expressed only in terms of the acoustic pressure as well as its normal and tangential derivatives, and their multiplication operators are based on the convected Green's kernel and its modified derivative. The proposed approach significantly reduces the CPU times of classical computational codes for modeling acoustic domains with arbitrary mean flow. It is validated by a comparison with the analytical solutions for the sound radiation problems of monopole, dipole and quadrupole sources in the presence of a subsonic uniform flow with arbitrary orientation.

Journal of Computational Science, 2017

Ce travail s'intéresse à l'étude du soudage par faisceau laser de l'alliage de magnés... more Ce travail s'intéresse à l'étude du soudage par faisceau laser de l'alliage de magnésium de désignation AM60. Il concerne un volet expérimental et un autre numérique. L'étude expérimentale vise l'investigation des conséquences métallurgiques et mécaniques du procédé sur l'alliage utilisé et la validation des résultats numériques du modèle thermique développé. En premier lieu, une étude paramétrique a permis de déterminer les paramètres du soudage par faisceau laser CO2 de plaques en alliage AM60 de 3 mm d'épaisseur. En deuxième lieu, la mise en œuvre d'une chaîne d'acquisition de la température, par des thermocouples implantés à proximité du cordon, a permis l'enregistrement de la température en fonction du temps au cours du soudage. En troisième lieu, l'étude métallographique de l'assemblage, a révélé que la structure à gros grain du métal de base est transformée en une structure dendritique au niveau de la zone fondue. Alors qu'a...

MÃ©canique & Industries, 2002

Lecture Notes in Mechanical Engineering, 2015

This paper focuses on the development of a mathematical model of arithmetic mean heights of surfa... more This paper focuses on the development of a mathematical model of arithmetic mean heights of surface (Sa) in friction stir welded AA2017 aluminium alloy using Taguchi L8 orthogonal design of experiments and response surface methodology. Machining variables such as rotation speed, traverse speed and tool shoulder diameter are considered in building the model. 3D surface topographies are used to characterize the surface roughness. The analysis of variance results showed that all the welding parameters are statistically significant at 95 % confidence level. According to Main Factor Plots, an increase in the rotation speed decreases the surface roughness while any increase in the traverse speed or the tool diameter shoulder increases it.