Papers by abdelkrim Liazid
The journal of engineering research, Apr 29, 2024
International Review of Civil Engineering (IRECE), 2015
In an industrial decentralization context of control and migration of intelligence downwards, mec... more In an industrial decentralization context of control and migration of intelligence downwards, mechanical equipments with more and more electronics and automations have been developed given the so called mechatronic systems. However this rapid progression of new technology has contributed to increase the systems complexity and decrease the mastering. The industrial diagnosis associated at a precocious detection of degradations have a key role in quality mastering, availability improve and productivity of the production tool. The industrial diagnosis methods are divided in two categories: diagnosis methods with formal model of the equipment and diagnosis methods without equipment model. The formal mathematical models of industrial equipments are often with uncertainties and difficult to built. This paper proposes a method based explanatory model which is best suited to model the cause-effect relationships essential for the industrial diagnosis. We adapt a novel tool of assistance to diagnosis based on the fuzzy Petri nets (FPN). An industrial application concludes this work.
Arabian Journal for Science and Engineering, 2014
This paper deals with the close numerical photogrammetry applications using several testing objec... more This paper deals with the close numerical photogrammetry applications using several testing objects. The different steps of the metrological process are recalled and discussed according to the obtained results. To get effective geometrical information on objects, automation by stereo matching is needed for profit ability and homogeneity requirements. The qualitative and quantitative evaluation of the 3D accuracy of measurements and the analysis of the resulting dot cloud is done according to a known reference. This study proposes restitution for metrological requirements using the method of dense epipolar matching. Mappings quite redundant and distributed on the images, but also a denser reconstruction are preferable for the application of the surface reconstruction. The use of a digital reflex body CANON EOS 5D with focal of 20 and 28 mm enabled us to observe concretely the influence of the measurements accurately and the step to be planned for a metrology project.
Modern Physics Letters B, Jun 19, 2023
The investigation of fluid flow and forced convective heat transfer in microchannels with square ... more The investigation of fluid flow and forced convective heat transfer in microchannels with square barriers is the focus of this study. The positioning of obstacles was varied in three cases: at the top wall, bottom wall, and symmetrically distributed on both sides of the microchannel wall. The thermal Lattice Boltzmann Method in conjunction with the Double Distribution Function and Bhatnagar–Gross–Krook approach was used for simulation through computer code in Python. Slip velocity and temperature jump were considered in the boundary conditions for the walls of the microchannel and obstacles. The results demonstrate that the rarefaction effect, placement of barriers, and choice of square obstacles significantly impact fluid flow and heat transfer. An increase in Knudsen numbers (Kn) leads to a decrease in temperature and velocity. The presence of obstructions on both sides of the microchannel walls reduces the fluid’s velocity and cools the fluid at the microchannel’s exit. The third case, with obstacles on both sides, presents a practical approach for reducing the fluid’s temperature at the exit, resulting in the lowest level of skin friction (Cf) and a reduction in the Nusselt number (Nu). The proposed configurations can be utilized to enhance the geometry of microchannels and for cooling purposes in small-scale devices and systems with miniature mechanical and electrical components. The study’s findings suggest that the placement of obstacles at the bottom or on both sides, depending on the need for best cooling on both sides or only at the top to reduce material consumption, can achieve low temperature at the exit of a rectangular microchannel.
Computer Methods and Programs in Biomedicine, May 1, 2023
International Review of Mechanical Engineering-IREME, May 31, 2013
This paper deals with the subject of natural gas-Hydrogen blends as alternative fuel for spark ig... more This paper deals with the subject of natural gas-Hydrogen blends as alternative fuel for spark ignition engine. First, a brief overview on previous works in this field was presented. Then, a numerical investigation focusedon the effect of hydrogen addition on the performances and emissions was also presented. A CFD approach using CONVERGE CFD Code was applied on a direct injection spark ignition engine at low regime and lean mixtures. A detailed chemistry associated with AMR (Adaptive Mesh Refinement) technique was adopted. To illustrate the effect of hydrogen addition to natural gas, three hydrogen fractions are considered 0%, 10% and 18%. The obtained results showthatthe promotion of the chemical reaction with hydrogen addition is mainly due to the increase of free radicals H, O, OH in the flame as a result of hydrogen addition. Hence, the heat release rate starting is advanced with the increase of hydrogen fraction while the combustion duration decreases. It is observed that the heat release rate and the maximum in cylinder temperature increase when hydrogen is added. Exhaust CO emissions decreases with the increase of hydrogen fraction, while NOx emissions increase. Hydrogen addition could give a great potential to reduce soot formation.
Thermal Science, 2009
The char ac ter is tics of pro pel lant in jec tion, mix ing, and com bus tion have a profound ef... more The char ac ter is tics of pro pel lant in jec tion, mix ing, and com bus tion have a profound ef fect on liq uid rocket en gine per for mance. The ne ces sity of rais ing rocket en gines per for mance re quires a com bus tion cham ber op er a tion of ten in a supercriti cal re gime. A super criti cal com bus tion model based on a one-phase multi-compo nents ap proach is de vel oped and tested on a non-pre mixed H 2-O 2 flame con fig ura tion. A two equa tions tur bu lence model is used for de scrib ing the jet dy nam ics where a lim ited Pope cor rec tion is added to ac count for the ox i dant spread ing rate. Trans port prop er ties of the mix ture are cal cu lated us ing ex tended high pres sure forms of the mix ing rules. An equi lib rium chem is try scheme is adopted in this combus tion case, with both al ge braic and sto chas tic ex pres sions for the chem is try/turbu lence cou pling. The model was in cor po rated into a com pu ta tional fluid dy nam ics com mer cial code (Flu ent 6.2.16). The va lid ity of the pres ent model was in ves tigated by com par ing pre dic tions of tem per a ture, spe cies mass frac tions, recirculation zones and vis i ble flame length to the ex per i men tal data mea sured on the Mascotte test rig. The re sults were con fronted also with ad vanced code sim u lations. It ap pears that the agree ment be tween the re sults was fairly good in the cham ber re gions sit u ated down stream the near in jec tion zone.
Biodiesel is a promising alternative to petroleum-based diesel fuel because it is renewable and i... more Biodiesel is a promising alternative to petroleum-based diesel fuel because it is renewable and its extensive use in unmodified engines has proved to be very successful. However, its future use may be limited by the higher oxides of nitrogen (NOx) emissions that are typically generated relative to petroleum diesel. This paper deals with the numerical investigations on the use of Waste Animal Fat (WAF) as alternative fuel in diesel engine. The advanced CFD code CONVERGE is used to perform this work. Computational methods were developed to estimate the physical and thermodynamic properties of biodiesel for combustion modeling. The data of physical WAF properties were input in the fuel library into CONVERGE program for modeling of the spray, ignition, combustion, and NOx emissions of biodiesel in diesel engine. The result validation is based on experimental data obtained from the a single cylinder direct injection diesel engine operated at its rated speed of 1800 rpm with a large range of applied loads. Comparison with the neat diesel fuel in achieved. The engine combustion parameters such as pressure, temperature, heat release rate are determined, and exhaust emissions (soot and NOx) are also evaluated at all operating conditions. Results show that when the engine is operated with WAF fuel, the combustion characteristics are slightly changed when compared to the neat diesel fuel. Also, the use of WAF fuel leads simultaneously to reduce soot and nitrogen oxides (NOx) species. This work is an achieved step with in-cylinder simulation of WAF fuel combustion and has illustrated that advancing the injection timing to 30 CA BTDC, improves pressure and consequently the brake thermal efficiency when using WAF fuel. In addition, the results reported in this paper illustrate that the numerical simulation can be one of the most powerful and beneficial tools for the internal combustion engine design, optimization and performance analysis.
Open Physics, 2022
This article aims to conduct a numerical investigation of phenomena induced by gas expansion in c... more This article aims to conduct a numerical investigation of phenomena induced by gas expansion in chemical propulsion nozzles. A numerical simulation of full-scale flat convergent-divergent nozzle geometry using the finite volume method on structured meshes is performed to predict the change in the convergent geometry on the boundary layer separation resulting from a shock/shock and shock/boundary layer. Two turbulence models are tested, namely, the k−ε and k−ω shear-stress transport (SST) models. Three steps are considered to achieve this work. First, 10 numerical schemes are tested to select the accurate one. The findings of the first step are used to predict the boundary layer separation in a supersonic overexpanded nozzle. The available experimental data from the NASA Langley Research Center are used to validate the results. The third step concerns investigating the impact of the convergent geometric profile on the downstream flow of the nozzle. The obtained results are analyzed and compared with the experimental data. These results show that convergent geometry may cause the formation of different shock structures and different points of flow separation and modifies several parameters of the flow and nozzle performance downstream the throat. The findings indicated that the convergent profile must be considered during the design phase when focusing on the problem of boundary layer separation in the supersonic overexpanded regime nozzles.
HAL (Le Centre pour la Communication Scientifique Directe), Jun 8, 2015
International Review of Mechanical Engineering-IREME, Jan 31, 2019
Journal of Mechanical Science and Technology, Aug 1, 2013
The present paper is devoted to the numerical modeling of turbulent reactive flows subjected to s... more The present paper is devoted to the numerical modeling of turbulent reactive flows subjected to spatial variations of equivalence ratio. In such situations, the description of the local thermochemistry requires at least two variables. The mixture fraction and the fuel mass fraction are respectively chosen to describe the composition of the fresh mixture and the chemical reaction progress. In the present contribution, a generalization of the Libby-Williams (LW) approach to four delta probability density function (Pdf) is presented. Transport equations for the first and second-order (variance) of mean scalar quantities are numerically solved. Moreover, the so-called LW-P model solves an additional transport equation for the cross-correlation between the reactive and the passive scalars. The model is applied to the calculation of a turbulent lean-premixed flow of methane and air stabilized by a near-stoichiometric pilot-flame. Numerical results regarding flow dynamics and flame structure are compared with the experimental data of a laboratory-scale burner-chamber device.
Mechanika, May 5, 2011
w-prewhirl angle, deg; 'H SF-skin friction losses; 'H P-power losses; 'H L-leakage losses; 'H DF-... more w-prewhirl angle, deg; 'H SF-skin friction losses; 'H P-power losses; 'H L-leakage losses; 'H DF-disc friction losses; 'H BL-blade loading losses; 'H INC-incidence losses;
HAL (Le Centre pour la Communication Scientifique Directe), Aug 24, 2009
HAL (Le Centre pour la Communication Scientifique Directe), 2007
HAL (Le Centre pour la Communication Scientifique Directe), 2007
ABSTRACT
World Academy of Science, Engineering and Technology, International Journal of Mechanical, Aerospace, Industrial, Mechatronic and Manufacturing Engineering, Nov 28, 2012
The process for predicting the ballistic properties of a liquid rocket engine is based on the qua... more The process for predicting the ballistic properties of a liquid rocket engine is based on the quantitative estimation of idealized performance deviations. In this aim, an equilibrium chemistry procedure is firstly developed and implemented in a Fortran routine. The thermodynamic formulation allows for the calculation of the theoretical performances of a rocket thrust chamber. In a second step, a computational fluid dynamic analysis of the turbulent reactive flow within the chamber is performed using a finite volume approach. The obtained values for the "quasi-real" performances account for both turbulent mixing and chemistryturbulence coupling. In the present work, emphasis is made on the combustion efficiency performance for which deviation is mainly due to radial gradients of static temperature and mixture ratio. Numerical values of the characteristic velocity are successfully compared with results from an industry-used code. The results are also confronted with the experimental data of a laboratory-scale rocket engine.
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Papers by abdelkrim Liazid