Browsing by Author "Kessal, M."

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    CFD analysis of hydrogen injection pressure and valve profile law effects on backfire and pre- ignition phenomena in hydrogen-diesel dual fuel engine
    (Elsevier, 2019) Menaa, Abdenour; Lounici, M.S.; Amrouche, F.; Loubar, K.; Kessal, M.
    This paper focuses on optimizing the hydrogen TMI (timed manifold injection) system through valve lift law and hydrogen injection parameters (pressure, injection inclination and timing) in order to prevent backfire phenomena and improve the volumetric efficiency and mixture formation quality of a dual fuel diesel engine operating at high load and high hydrogen energy share. This was achieved through a numerical simulation using CFD code ANSYS Fluent, developed for a single cylinder hydrogen-diesel dual fuel engine, at constant engine speed of 1500 rpm, 90% of load and 42.5% hydrogen energy share. The developed tool was validated using experimental data. As a results, the operating conditions of maximum valve lift ¼ 10.60 mm and inlet valve closing ¼ 30 CA ABDC (MVL10 IVC30) prevent the engine from backfire and pre-ignition, and ensure a high volumetric efficiency. Moreover, a hydrogen start of injection of 60 CA ATDC (HSOI60) is appropriate to provide a pre-cooling effect and thus, reduce the pre-ignition sources and helps to quench any hot residual combustion products. While, the hydrogen injection pressure of 2.7 bar and an inclination of 60 , stimulate a better quality of hydrogen-air mixture. Afterwards, a com- parison between combustion characteristics of the optimized hydrogen-diesel dual fuel mode and the baseline (diesel mode) was conducted. The result was, under dual fuel mode there is an increase in combustion characteristics and NOx emissions as well as a decrease in CO2 emissions. For further improvement of dual fuel mode, retarding diesel start of injection (DSOI) strategy was used.
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    Deposition of wax in pipelines under laminar flow conditions
    (2009) Boucetta, R.; Kessal, M.
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    Dépôt de paraffine dans une conduite circulaire
    (2010) Boucetta, R.; Kessal, M.
    Une étude sur l’écoulement des fluides visqueux chargés de paraffine est menée sur la base des équations du mouvement, du transfert de chaleur et du transfert de masse (par diffusion moléculaire et dispersion de cisaillement). Ces dernières sont réécrites sous une forme adimensionnelle. Une résolution numérique du nouveau système d’équations, par la méthode de Runge-Kutta d’ordre quatre, est réalisée pour deux cas pratiques courants afin de prévenir le problème d’obstruction des conduites
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    Effect of the latent heat on wax deposit in pipelines
    (2011) Boucetta, R.; Kessal, M.
    Wax deposition continues to be a relevant problem for petroleum production and transportation pipelines. This viscous and waxy flow is theoretically modelled with a simple conservation equation system, by expressing the wax layer thickness as function of time and duct length. The flow parameters are written, depending on these independent variables but also on the Reynolds and the Peclet numbers, where effect of latent heat on the wax layer thickness deposit is investigated. A numerical simulation of the flow, for two practical cases, is performed in order to predict the pipeline obstruction
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    Experimental study of boiling heat transfer on multiple and single nucleation sites using a boiling-meter
    (Taylor and Francis Group, 2013) Tadrist, L.; Zamoum, Mohammed; Combeau, H.; Kessal, M.
    The general objective of this study is to contribute to a better understanding of heat transfer in a nucleate boiling regime. The aim is to determine the heat transfer characteristics under controlled operating conditions (thermodynamics of the fluid, noncondensable gas, surface state). Experimental investigations have been carried out in natural convection and nucleate boiling regimes. An experimental device was realized to perform boiling experiments using a boiling-meter, allowing investigations for different orientations of the wall. The boiling-meter is designed to investigate boiling for single and multiple nucleation sites. The purpose of this paper is to detail the experimental setup as well as the boiling-meter. This device allows the determination of the temporal heat transfer characteristics evolutions. In particular, this new device allows bringing to light the phenomenon of nucleation, growth, and detachment of generated vapor bubbles on a single artificial nucleate site, as well as for multiple natural nucleation sites. First results of the influence of the orientation of the heating wall for multiple and single nucleation sites on heat transfer are presented and analyzed
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    Gas release effect on transient homogeneous bubbly flow parameters
    (2000) Kessal, M.
    A one-dimensional homogeneous bubbly flow model is developed taking into account the gas release phenomena. In order to analyze its effect, the three conservation equations are solved numerically by a predictor-corrector finite difference scheme and also by an improved characteristic method. A good agreement is noticed in comparison with others authors experimental and computed results. Beside this, approximate models of gas release rate are performed and compared by studying the diffusion phenomena
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    An investigation of highly pressurized transient fluid flow in pipelines
    (2012) Ouchiha, Z.; Loraud, J. C.; Ghezal, A.; Kessal, M.; Benzaoui, A.; Ghiaasiaan, M.
    This paper discusses transient processes in natural gas pipelines. The method of characteristics (MOC) is applied for the analysis of two transient categories, where the governing one-dimensional, hyperbolic conservation equations are linearized and solved without neglecting any of their term. First, we present a parametric study of the pressurized flow encountered when pipelines are utilized for the transportation or the temporary storage of natural gas. The non-ideal compressibility of natural gas is included in the model and its impact on the thermo-hydraulic processes is elucidated. Second, we model the hydrodynamics of a pipeline whose downstream boundary is a periodic discharge rate. The results show that, in response to these boundary conditions, the pressure distribution in the pipeline also undergoes periodic variations. Furthermore, our simulation results confirm the usefulness of MOC for numerical simulation of flow phenomena in pipelines
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    The modeling of dissolved gas effect on liquid transients
    (American Society of Mechanical Engineers, 2006) Kessal, M.; Bennacer, R.
    Transient cavitation of a homogeneous gas-liquid mixture flow is modeled for an elastic pipeline by using the classical conservation equations of each phase, which are, later on, written in dimensionless form. The later is resolved by a second order finite difference scheme for which a flux corrective transport algorithm is added as an additional step, in order to accomplish a suitable treatment of the shock problem. The flow gives rise to a localized vapor+gas cavity for which time and space expansion is calculated from the corresponding compatibility relation, continuity equation and ideal gas law. Also, effect of the degassing phenomenon, on this cavity and on the dynamic parameters, is reproduced from a macroscopic bubble growth model. Obtained results are discussed and compared with ones given by experimental data
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    Modelisation du depot de paraffine lors d'un ecoulement ascendant de petrole
    (Wiley Online Library, 2010) Boucetta, R.; Kessal, M.
    A study on the upslope flow of heated petroleum paraffin was conducted based on motion equations and heat transfer, which were rewritten in a completely dimensionless form to analyze the influence of temperature on the position of the deposit point and its change over time. A numerical resolution of the new equation system, based on the Runge-Kutta 4th order method, was performed for two current practical cases to avoid the line obstruction problem. Une étude sur l'écoulement ascendant de pétrole, chauffé et chargé en paraffine, est menée sur la base des équations du mouvement et du transfert de chaleur. Ces dernières sont réécrites sous une forme adimensionnelle complète, afin d'analyser l'influence de la température sur la position du point de déposition et son évolution en fonction du temps. Une résolution numérique du nouveau système d'équations, basée sur la méthode de Runge-Kutta d'ordre quatre, est réalisée pour deux cas pratiques courants afin de prévenir le problème d'obstruction des conduites
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    A new gas release model for a homogeneous liquid–gas mixture flow in pipelines
    (2005) Kessal, M.; Bennacer, R.
    The gas release phenomenon, resulting from a rapid decompression in a homogeneous gas–liquid flow is expressed by multiplying the mixture density by a degassing coefficient Gr. The effect of this coefficient is calculated by using the classical conservation equations of fluid mechanics and diffusion laws. These equations are solved by an improved new two time step finite difference scheme. The method of characteristics is used at the boundaries. The theoretical results obtained are in good agreement with experimental data and confirm the gas release effect on the flow parameters. q 2005 Elsevier Ltd. All rights reserved
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    Numerical simulation of transient vaporous and gaseous cavitation in pipelines
    (2001) Kessal, M.; Amaouche, Mustapha
    The transient vaporous and gaseous cavitation phenomena in an elastic pipeline are investigated for homogeneous liquid-gas mixture flow. It has been shown, in the case of two components having the same velocity, that modelling is also possible by considering the continuous character of the medium, i.e. without any location of column separation. The governing equations have been solved by using two finite difference schemes: the Mac Cormack’s scheme and an improved new finite difference two-time step scheme. Characteristics method is used at the boundaries. The theoretical results obtained are compared and found to correlate well with similar results
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    Simplified numerical simulation of transients in gas networks
    (2000) Kessal, M.
    A set of equations governing an isothermal compressible fluid flow is resolved numerically for two practical cases. The first case concerns the fast fluid flow in short gas pipelines where the equations, written in conservative form, are resolved by a predictor-corrector scheme for the interior mesh points: an improved Lax-Friedricks scheme as a predictor and a leapfrog scheme as a corrector. Characteristics and upwind methods are used for the boundary conditions. The second case is concerned with massic slow fluid flow in relatively long gas pipelines. The equations, written in non conservative form, are resolved by a simple explicit finite difference scheme. The boundary conditions are considered by using the characteristic form of the equations including an inertial multiplier (Yow model) and resolved by a Newton-Raphson method. The obtained results agree with those of other methods. These numerical experiments permit the user to gain more computational time and simplicity in comparison with methods
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    A Wall Effects and Means of Controlling the Evolution of Swirling Flows with Vortex Breakdown
    (JAFM, 2023) Meziane, Akila; Hachemi, M.; Kessal, M.; Imoula, M.
    This paper investigates numerically the bubble-type vortex breakdown apparition in the case of closed rotating flows of a viscous, axisymmetric, and incompressible fluid. First, a truncated conical/cylindrical cavity of spherical end disks is used to simulate and analyze the vortex structure under rigid surface conditions. The geometric effects of the enclosure are also studied. Vortex breakdown is demonstrated beyond the lower disk rotation rate threshold by introducing the no-slip condition imposed on the upper wall. The objective is to explore ways of controlling the evolution of this physical event by modifying the confinement conditions upstream of the vortex rupture. Particular attention is also paid to the effective kinematic viscosity, thermal diffusivity and geometric control of recirculation zones on the axis of rotation (axial bubble type). The second geometry consists of a spherical annulus formed by two concentric hemispheres in differential rotation under plat-free surface conditions. The results show that rotation of the inner hemisphere induces a vortex bubble on the polar axis. In contrast, the outer hemisphere rotation induces a toroidal vortex on the equator