Browsing by Author "Manser, Belkacem"

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Analysis of natural convection heat transfer in a rectangular cavity with discrete heat flux: Implications for building thermal management using artificial neural networks
(Taylor and Francis Ltd., 2024) Rachedi, Kamel; Ragueb, Haroun; Behnous, Dounya; Tahiri, Antar; Manser, Belkacem; Ait Chikh, Mohamed Abdessamed
This study numerically investigates free convection within a rectangular air-filled cavity, simulating real-romm conditions. The top, bottom, and one sidewall are at constant temperatures, while the opposite sidewall has a constant discrete heat flux, akin to heater appliances. The impact of heating intensity, length, and position on temperature distribution is explored. Artificial Neural Networks (ANN) are utilized to correlate the average Nusselt number, providing a model for engineering applications in building thermal management. The dataset includes 2436 simulation runs with varying parameter: Rayleigh number (103 to 106), aspect ratio (0.5 to 2), heating surface length (0.1 to 1), and elevation (0.05 to 0.95). Results show increased Rayleigh numbers intensify the stream function and promote uniform temperature distribution. The elevation of the heating surface influences temperature distribution, with placement closer to the floor or ceiling optimizing heat transfer. ANN modeling predicts the average Nusselt number with high precision (±3%).
Approches numériques pour la résolution des problèmes des paliers hydrodynamiques, liés aux contraintes géométriques et mécaniques
(2019) Manser, Belkacem; Belaidi, Idir (Directeur de thèse)
Les paliers hydrodynamiques, éléments de machines omniprésents dans la construction des systèmes mécaniques, sont utilisés pour guider et supporter les arbres en rotation, particulièrement appréciées pour ses caractéristiques d’amortissement à hautes vitesses de rotation. Cependant les performances des machines tournantes lubrifiées par un film fluide sont impactées par de nombreux paramètres interactifs non linéaires, difficiles à analyser. La prédiction du comportement du système par simulation numérique nécessite par conséquent une modélisation approfondie de l’écoulement du lubrifiant dans les paliers hydrodynamiques. C’est dans ce contexte que nous proposons une étude numérique de l'influence des différends paramètres liés aux contraintes mécaniques et géométriques sur les performances d'un palier lisse circulaire de dimensions finies, soumis à une charge et un moment statiques, et fonctionnant en régime hydrodynamique, isotherme et stationnaire établi. Les effets induits par la géométrie du palier (excentricité relative), le degré et l'angle du mésalignement de l’arbre, le comportement rhéologique du lubrifiant de types micropolaire et la configuration (forme, disposition et densité) de textures sur l'évolution des performances du palier ont été analysés et dissertés. Notre approche numérique est de ce fait basée sur la modélisation de l’équation de Reynolds modifiée, en tenant compte des différents paramètres d’influence, tels que : la rupture et la reformation du film fluide, le mésalignement de l'arbre et la texturation de surface du coussinet, ainsi que la non linéarité de la viscosité du fluide et de son comportement rhéologique. Les développements algorithmiques inhérents au modèle mathématique développé ont été mise en œuvre et implémentés sous MATLAB®, dans un code robuste, basé sur la discrétisation basée sur le schéma aux différences finies centrées et la résolution par la méthode itérative de Gauss-Seidel. La validation du modèle numérique parachève cette contribution en s’adossant à une comparaison des résultats obtenus avec des résultats publiés, mettant notamment en exergue une corrélation appréciable de ces résultats. Enfin, une étude de l'influence des différents paramètres interactifs, tels que la rupture du film, l’état de surface, le mésalignement, le comportement micropolaire du lubrifiant, a fait également l’objet d’une étude minutieuse
Irreversibilities and heat transfer in magnetohydrodynamic microchannel flow under differential heating
(Elsevier, 2023) Ragueb, Haroun; Tahiri, Antar; Behnous, Dounya; Manser, Belkacem; Rachedi, Kamel; Mansouri, Kacem
This study investigates heat transfer and entropy generation in a microchannel subjected to differential heating, viscous dissipation, and Joule heating within a magnetohydrodynamic (MHD) fluid flow. A finite difference method with a fully implicit scheme is employed to accurately model temperature distribution and entropy generation. A comparison between the average Nusselt numbers (Nu) calculated using the classical method and the Bennett Formula reveals a notable discrepancy, particularly at the entry length (up to 14%). It has been found that when one plate is heated while the other is cooled and the Hartmann number (Ha) is low, the average Nu for both plates converges to 2. However, at high Ha values considering viscous dissipation and Joule heating, there is an 8% deviation between the Nu values of the two plates, with the higher Nu found on the cooling plate. Sensitivity analyses explore the impact of control parameters on entropy generation, emphasizing the significance of η as a key parameter that reflects the system's resistance to entropy generation. Increasing η from 0.1 to 0.5 results in a 32% reduction in entropy generation. In particular, for microchannels, substantial η high values imply reduced entropy generation, highlighting their efficiency in heat transfer.
Numerical analysis of steady-state performances of hydrodynamic misaligned journal bearings considering surface texturing effects
(2018) Manser, Belkacem; Belaidi, Idir; Khelladi, Sofiane; Hamrani, Abderrachid
Misalignment affects nearly all the bearing performance characteristics including the minimum film thickness, pressure field, friction torque, leakage flow rate, and moments. This study presents investigations related to the combined influences of shaft misalignment and texture location on the hydrodynamic journal bearing performances. A numerical study is used in the analysis of spherical texture shape effects on misaligned bearing characteristics. The Reynolds equation of thin viscous films is solved using finite difference technique by taking into account Reynolds boundary conditions. The numerical results show that the performances of misaligned journal bearings can be improved through an appropriate arrangement of the textured location on the contact surface
Performance of hydrodynamic journal bearing under the combined influence of textured surface and journal misalignment : a numerical survey
(Elsevier, 2019) Manser, Belkacem; Belaidi, Idir; Hamrani, Abderrachid; Khelladi, Sofiane; Bakir, Farid
A reduced-order method with PGD for the analysis of dynamically loaded journal bearing
(2022) Megdoud, Abdelhak; Manser, Belkacem; Belaidi, Idir; Bakir, Farid; Khelladi, Sofiane
Machine component design has become a prominent topic for researchers in recent years. The analysis of bearing systems has received considerable attention in order to avoid detrimental contact. Among the most important studies in this area are the transient problems of journal bearings, which are usually performed by coupling the Reynolds equation with the motion equations. Many techniques have been presented in the literature and are still being explored to ensure the accurate findings and efficient solution prediction of unsteady state Reynolds equation. In this paper, the Proper Generalized Decomposition (PGD) approach is expanded for the analysis of the lubricant behavior of dynamically loaded journal bearing considering Swift-Stieber boundary conditions. The PGD model is applied in this problem, seeking the approximate solution in its separated form of the partial differential Reynolds equation at each time step during the load applied cycle employing the alternating direction strategy. Compared to the classical resolution, the PGD solution has a considerably low computational cost. To verify the accuracy and efficiency of this approach, three cases have been considered, infinitely short, infinitely long and finite journal bearings under the dynamic load. The results of the suggested methodology when compared to the full discretized model (FDM) show that, the new scheme is more efficient, converges quickly, and gives the accurate solutions with a very low CPU time consumption.
A reduced-order method with PGD for the analysis of mis- aligned journal bearing
(2021) Megdoud, Abdelhak; Manser, Belkacem; Belaidi, Idir; Bakir, Farid; Khelladi, Sofiane
n recent years, machine component design has been a major con- cern for researchers. Emphasis has been placed especially on the analysis of bearing systems in order to avoid detrimental contact. The shaft misalignment is one of the most problems that affects directly the operating conditions of these components. In this context, the present study proposes a reduced-order method "Proper Generalized Decomposition" (PGD) using the separation tech- nique through the alternating direction strategy to solve the modified Reynolds equation, taking into account the presence of misalignment in the shafting sys- tem. The solution shows the representation of two types of misalignment ge- ometry, especially axial and twisting. A comparison of the results between the proposed approach and the classical method, through several benchmark ex- amples, made it possible to highlight that the new scheme is more efficient, converges quickly and provides accurate solutions, with a very low CPU time expenditure.
Texture shape effects on hydrodynamic journal bearing performances using mass-conserving numerical approach
(Taylor & Francis, 2020) Manser, Belkacem; Belaidi, Idir; Hamrani, Abderrachid; KHELLADI, Sofiane
It is a known fact that incorporating textures in the contact surfaces can significantly enhance bearing performances. The purpose of this paper is to outline the effects of texture bottom profiles and contour geometries on the performances of hydrodynamic textured journal bearings. The analysis was conducted using computational approach to test eight texture shapes: rectangular, cylindrical, spherical, triangular (TR, T1, T2, T3) and chevron. The steady-state Reynolds equation for modelling the hydrodynamic behaviour of thin viscous film was solved using finite difference technique and mass conservation algorithm (JFO boundary conditions), taking into account the presence of textures on both full film and cavitation regions. The comparison with the benchmark data shows good consistency and an enhancement in bearing performances (load carrying capacity and friction). The results clearly show that the mechanisms of wedge effect and micro-step bearing for the full/partial texturing feature are the main crucial parameters, where the convergent wedge effect present in T2 triangular texture shape can significantly enhance the load-carrying capacity, while the divergent wedge action causes a net load loss. Considering the right arrangement of textures on the contact surface, their surface contours can have a significant impact on the performance of hydrodynamic journal bearings at high eccentricity ratios
Thermal analysis of steady-state performances of hydrodynamic misaligned journal bearings considering surface texturing effects
(2018) Manser, Belkacem; Belaidi, Idir; Khelladi, Sofiane; Hamrani, Abderrachid
Bearing misalignment can affects nearly all operating performances: minimum film thickness, pressure distribution, thermal field, friction torque, leakage flow rate, and cavitation. In this study, we present a computational investigation related to the combined influence of surface texturing and journal misalignment on the performances of hydrodynamic journal bearing. To this end, a numerical analysis is performed to analyze the effect of a spherical texture shape on misaligned bearing characteristics. The model employed herein is solved using a finite differences scheme with mass conservation algorithm (JFO boundary conditions) and oil mixing temperature concept. Preliminary results are consistent with the reference ones, and show that the performances of a misaligned journal bearing can be improved with an appropriate surface texturing topography