Browsing by Author "Zamoum, Mohammed"

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    Analysis of cavitating flow through a venturi
    (2015) Zamoum, Mohammed; Kessal, Mohand
    A dynamical study of a bubbly flows in a transversal varying section duct (Venturi), is modeled by the use of the mass and momentum phases equations, which are coupled with the Rayleigh-Plesset equation of the bubbles dynamics. The effects of the throat dimension and the upstream void fraction on flow parameters are investigated. The numerical resolution of the previous equations set let us found that the characteristics of the flow change dramatically with upstream void fraction. Two different flow regimes are obtained: a quasi-steady and a quasi-unsteady regimes. The former is characterized by a large spatial fluctuations downstream of the throat, which are induced by the pulsations of the cavitation bubbles. The quasi-unsteady regime corresponds to flashing flow in which occurs a bifurcation at the flow transition between these regimes. This transition occurs at Rc 4.3 which corresponds to s 4.710-3. An analytical expression for the critical bubble size at the flashing flow point is also obtained and compared with theoretical data
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    Bubbly Cavitating Flow T hrough a Converging Nozzle
    (MCM'20, 2020) Zamoum, Mohammed; Boucetta, Rachid; Kassel, Mohand
    In the present work , the bubbly cavitating flow phenomena after passing through the converging nozzle is numerically investigated.The dynamicof the cavitating bubbles is modeled by the use of the mass and momentum phase’s equations, which are coupled with the Rayleigh -Plesset equation of the N bubbles dynamics However, assuming that the same initial conditions of all bubbles are identical and that all bubbles are equidistant from each other simplifies the governing equations. Equation set is numerically resolved by the use of a fourth order Runge-Kutta scheme.The numerical resolution of the previous equations set let us found that the bubble radius distribution, fluid velocity and fluid pressure change dramatically with upstream void fraction and a n instability appeared just after the passing the converging nozzle for both cases one bubble N=1and two bubbles N=2. Indeed, for the case of one bubble N=1, the flashing flow phenomena occurs for an upstream void fraction αs=11.2x10-3, which corresponds to a critical bubble radius Rc=1.8. Whereas, for bubble number N=2, the same phenomenon occurs for αs= 8.9x10-3, with Rc=2. This difference is due to the bubble interaction . Also,we found that, the bubble number N strongly affect the bubble frequency. However, with increase the bubble number, the maximum size of the bubbles increases and bubble frequency oscillation decrease.
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    Etude expérimentale de l'ébullition mono et multi-sites en régime d'ébullition nucléée : analyse de la nucléation et de la dynamique des bulles associées aux transferts de chaleur
    (2014) Zamoum, Mohammed
    L’objectif de cette étude est de contribuer à une meilleure compréhension des transferts de chaleur en régime d’ébullition nucléée. Il s’agit de déterminer les paramètres caractéristiques des transferts de chaleur avec des conditions opératoires bien maîtrisées (état thermodynamique du fluide, incondensables, état de surface…etc). Les investigations expérimentales sont menées dans les régimes de convection naturelle et d’ébullition nucléée. Un dispositif expérimental a été conçu et mis en oeuvre.il s’agit pour l’essentiel de la cellule de test et de l’ébulliomètre. Ce dispositif permet de réaliser des expériences d’ébullition mono et multi-sites sur une paroi orientable allant de 0 à 180° (L'angle 0° correspond à une paroi horizontale avec un flux de chaleur vertical orienté vers le haut) dans différentes conditions de saturations. Les résultats obtenus permettent de mettre en évidence le phénomène de nucléation, croissance et détachement de bulles générées sur un site de nucléation artificiel unique. Nous montrons en particulier un résultat original sur l’influence de l’orientation de la paroi chauffante et l’influence de la pression de saturation du fluide sur la densité du flux de chaleur échangé entre la paroi et le fluide. Et par conséquence, l’influence de ces derniers sur le déclenchement de la nucléation (ONB)
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    Etude expérimentale de l'ébullition mono et multi-sites en régime d'ébullition nucléée : analyse de la nucléation et de la dynamique des bulles associées aux transferts de chaleur
    (2014) Zamoum, Mohammed
    L’objectif de cette étude est de contribuer à une meilleure compréhension des transferts de chaleur en régime d’ébullition nucléée. Il s’agit de déterminer les paramètres caractéristiques des transferts de chaleur avec des conditions opératoires bien maîtrisées (état thermodynamique du fluide, incondensables, état de surface…etc). Les investigations expérimentales sont menées dans les régimes de convection naturelle et d’ébullition nucléée. Un dispositif expérimental a été conçu et mis en oeuvre.il s’agit pour l’essentiel de la cellule de test et de l’ébulliomètre. Ce dispositif permet de réaliser des expériences d’ébullition mono et multi-sites sur une paroi orientable allant de 0 à 180° (L'angle 0° correspond à une paroi horizontale avec un flux de chaleur vertical orienté vers le haut) dans différentes conditions de saturations. Les résultats obtenus permettent de mettre en évidence le phénomène de nucléation, croissance et détachement de bulles générées sur un site de nucléation artificiel unique. Nous montrons en particulier un résultat original sur l’influence de l’orientation de la paroi chauffante et l’influence de la pression de saturation du fluide sur la densité du flux de chaleur échangé entre la paroi et le fluide. Et par conséquence, l’influence de ces derniers sur le déclenchement de la nucléation (ONB)
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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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    Heat transfer investigation near the onset of nucleate boiling on a single artificial nucleate site: Influence of the wall orientation
    (Elsevier, 2025) Kharkwal, Himanshi; Zamoum, Mohammed; Barthès, Magali; Lanzetta, François; Combeau, Hervé; Tadrist, Lounès
    Studying the transition from natural convection to nucleate boiling is crucial for both the efficiency and safety of thermal systems. Present study aims to investigate the heat transfer characteristics at the transition of the natural convection and the nucleate boiling regimes. An experimental setup has been designed and implemented to perform experiments with FC72 on flat heating wall that can be inclined from 0° to 180°. This was possible thanks to the development of a boiling meter mounted on a pivoting axis. This work provides new insights into local wall heat transfer behavior and nucleation dynamics under varying gravitational configurations, contributing novel data on single-site boiling physics. Intermittent behavior with typical heat transfer cycles is evidenced. Two criteria are found to control this intermittency; the wall temperature threshold for bubble nucleation and the heat flux threshold needed to sustain bubble emission. A single isolated bubble leads to a variation in the transfer coefficient. Changing inclination from 0° to 180° increases the heat transfer coefficient in the bubble emission regime from 263 to 489 W/(m2 °C) but decreases it in natural convection from 240 to 176 W/(m2 °C)
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    Numerical investigation of cavitating flow in a horizontal converging-diverging nozzle
    (2021) Zamoum, Mohammed; Boucetta, Rachid; Kessal, Mohand
    The objective of this paper is to investigate the dynamic evolution of cavitating flow in a horizontal converging-diverging Venturi nozzle. A nonlinear continuum bubbly mixture model coupled with the dynamics equation of the bubble is used to investigate the effects of the throat dimension of converging-diverging nozzle. Equation set is numerically resolved by the use of a fourth order Runge-Kutta scheme. The numerical resolution of the previous equations set let us found that the bubble radius distribution, fluid velocity and fluid pressure change dramatically with the throat length of the Venturi and an instability appeared just after the passing the converging nozzle for an throat length greater than 4.2 cm which correspond to the critical bubble radius Rc= 6.85. Also, we found that, the throat dimension of converging diverging nozzle has strongly affected the bubble frequency and the characteristics of the flow
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    Numerical investigation of wax deposition features in a pipeline under laminar flow conditions
    (Elsevier, 2022) Boucetta, Rachid; Haddad, Zoubida; Zamoum, Mohammed; Kessal, Mohand; Arıcı, Müslüm
    Wax deposit inside pipelines continues to be a critical issue in the oil and gas industry. The available wax deposition data in the literature are currently insufficient to construct viable predictive numerical methods that capture all wax deposit features. Therefore, more research studies are required to improve our understanding of the physics of wax-deposition phenomena. In the present paper, a numerical study is performed to predict the temporal and spatial distribution of the porous wax deposit during laminar flow in a pipe. A mathematical model which combines the energy and momentum balance equations and molecular diffusion model by Fick's law is employed to better describe the wax deposit. Validation with experimental data as well as numerical results and characteristics of wax deposition are presented. The results revealed that an increase in the deposition time and porosity leads to a significant increase in the wax deposit content and pressure drop, and a decrease in the fluid temperature, heat transfer coefficient, and flow rate. However, an increase in porosity leads to larger variation of these parameters over a short period of time. Further, it is demonstrated that the wax deposit is concentrated over a short axial length, and its maximum which appears at X/L = 0.014 is kept unchanged with time and porosity variation
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    Numerical modeling of transients in gas pipeline
    (Academic Journals, 2014) Kessal, Mohand; Boucetta, Rachid; Zamoum, Mohammed; Tikobaini, Mourad
    A set of equations governing an isothermal compressible fluid flow is analytically and numerically analyzed. The obtained equations are written in characteristic from and resolved by a predictorcorrector lambda sceme for the interior mesh points. The method of characteristics (MOC) is used for the boundaries. Advantages of explicit form of these schemes and the flexibility of the MOC are used for an isothermal fast transient gas flow in short pipeline. The results, obtained for a simple practical application agree with those of other methods
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    Split Control Wind Turbine Airfoil noise with CFD and Acoustic Analogies
    (Isfahan University of Technology, 2024) Khenfous, Soumia; Maizi, Mohamed; Zamoum, Mohammed
    This research aims to investigate the impact of a split airfoil on noise emissions from a horizontal-axis wind turbine. The objective is to comprehensively understand the airflow patterns around the airfoil to reduce noise emissions. The study rigorously examines a range of angles of attack, from 0° to 25°, for both the original airfoil and the airfoil with a split, using advanced computational aerodynamics coupled with analog acoustic analysis. The methodology involves two-dimensional flow simulations with Delayed Detached Eddy Simulation based on the Spalart-Allmaras model, enabling precise near-field flow calculations around the airfoil. Additionally, far-field noise predictions, employing the Ffowcs Williams and Hawkings analogy based on simulated sources, reveal the efficacy of the split airfoil design. Results indicate that the split airfoil design effectively reduces noise emissions across various angles of attack. These reductions translate into a significant decrease in the Overall Sound Pressure Level, ranging from 14% to 19%, and remarkable Sound Pressure Level reductions between 12% and 60% across diverse frequencies, showcasing substantial noise improvements in various frequency ranges.