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1
Content available Evaluation of the effect of rotational speed and rheological nature on heat transfer of complex fluid between two cylinders
Benmansour Abdelhalim, Laidoudi Houssem
Archives of Thermodynamics
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2024
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Vol. 45, no 1
65--73
EN
This paper presents numerical results for flow behavior between a cold inner cylinder and a hot outer cylinder. Both cylinders are placed horizontally. The space separating the two compartments is completely filled with a fluid of a complex rheological nature. In addition, the outer container is subjected to a constant and uniform rotational speed. The results of this work were obtained after solving the differential equations for momentum and energy. The parameters studied in this research are: the intensity of thermal buoyancy, the speed of rotation of the outer container and the rheological nature of the fluid. These elements are expressed mathematically by the following values: Richardson number (Ri = 0 and 1), Reynolds number (Re = 1 to 40), power-law number (n = 0.8, 1 and 1.4) and Prandtl number (Pr = 50). The results showed that the speed of rotation of the cylinder and the rheological nature of the fluids have an effective role in the process of heat transfer. For example, increasing the rotational speed of the enclosure and/or changing the nature of fluid from shearthickening into shear-thinning fluid improves the thermal transfer rate.
2
Content available Study of the effect of geometric shape on the quality of mixing: Examining the effect of length of the baffles
Bouchouicha Malika Seddik, Laidoudi Houssem, Hassouni Souad, Makinde Oluwole Daniel
Archives of Thermodynamics
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2023
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Vol. 44, no 2
69--85
EN
This work is an attempt to study the behaviour of fluid in the mixing vessel with a two-bladed or four-bladed impeller. The working fluid is complex, of a shear-thinning type and the Oswald model is used to describe the fluid viscosity. The study was accomplishedby numerically solving the governing equations of momentum and continuity. These equations were solved for the following range of conditions: 50–1000 for the Reynolds number, 0–0.15 for the baffle length ratio, and the number of impeller blades 2 and 4. The simulations were done for the steady state and laminar regime. The results show that the increase in baffle length (by increasing the ratio baffle length ratio) decreases the fluid velocity in the vessel. Increasing the speed of rotation of the impeller and/or increasing the number of blades improves the mixing process. Also, the length of the baffles does not affect the consumed power.
3
Content available A qualitative study of mixing a fluid inside a mechanical mixer with the effect of thermal buoyancy
Hassouni Souad, Laidoudi Houssem, Makinde Oluwole Daniel, Bouzit Mohamed, Boumediene Haddou
Archives of Thermodynamics
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2023
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Vol. 44, no 1
105--119
EN
This paper is concerned with the rotational motion of the impeller and the thermal buoyancy within a mechanical mixer. The task was investigated numerically using the ANSYS-CFX simulator. The programmer is based on the finite volume method to solve the differential equations of fluid motion and heat transfer. The impeller has hot surfaces while the vessel has cold walls. The rotational movement of the impeller was controlled by the Reynolds number, while the intensity of the thermal buoyancy effect was controlled by the Richardson number. The equations were solved for a steady flow. After analyzing the results of this research, we were able to conclude that there is no effect of the values of Richardson number on the power number. Also, with the presence of the thermal buoyancy effect, the quality of the fluid mixing becomes more important. The increasing Richardson number increases the value of the Nusselt number of the impeller.
4
Content available 3D simulation of incompressible flow around a rotating turbulator: Effect of rotational and direction speed
Zoubai Elhadi, Laidoudi Houssem, Tlanbout Ismail, Makinde Oluwole Daniel
Archives of Thermodynamics
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2023
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Vol. 44, no 2
139--157
EN
This paper presents new results for the dynamic behaviour of fluid around a rotating turbulator in a channel. The turbulator has a propeller form which is placed inside a flat channel. The research was carried out using 3D numerical simulation. The rationale of the experiment was as follows: we put a propeller-turbulator inside a flat channel, and then we insert a water flow inside the channel. The turbulator rotates at a constant and uniform speed. The main points studied here are the effect of the presence of turbulator and its rotational direction on the flow behaviour behind the turbulator. The results showed that the behaviour of flow behind the turbulator is mainly related to the direction of turbulator rotating. Also, the studied parameters affect coefficients of drag force and power number. For example, when the turbulator rotates in the positive direction, the drag coefficient decreases in terms of rotational speed of the turbulator, while the drag coefficient increases in terms of rotational speed when the turbulator rotates in the negative direction.
5
Content available Behaviour of a non-newtonian fluid in a helical tube under the influence of thermal buoyancy
Ramla Mohamed, Laidoudi Houssem, Bouzit Mohamed
Acta Mechanica et Automatica
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2022
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Vol. 16, no. 2
111--118
EN
This work is an evaluative study of heat transfer in the helical-type heat exchanger. The fluid used is non-Newtonian in nature and is defined by Oswald’s model. The work was performed numerically by solving each of the Navier–Stokes equations and the energy equation using the package ANSYS-CFX. Following are the aspects that have been dealt with in this paper: the effects of thermal buoyan-cy, fluid nature and the tube shape on the heat transfer, and the fluid comportment. The interpretation of the obtained results was done by analyzing the isotherms and the streamlines. The mean values of the Nusselt number were also obtained in terms of the studied parame-ters. The results of this research enabled us to arrive at the following conclusion: the intensity of thermal buoyancy and the nature of the fluid affect the heat transfer distribution but keep the overall rate of heat transfer the same.
6
Content available Natural convection from four circular cylinders in across arrangement within horizontal annular space
Laidoudi Houssem
Acta Mechanica et Automatica
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2020
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Vol. 14, no. 2
98--102
EN
Numerical investigation is accomplished to study the roles of governing parameters of natural convection on the fluid motion and heat transfer rate of four heated circular cylinders placed inside a circular enclosure of cold surface. The cylinders are positioned in across arrangement. The representative results are obtained within the ranges of initial conditions as: Prandtl number (Pr = 7.1 to 1000) and Rayleigh number (Ra = 103 to 105). The average Nusselt number of each inner cylinder is computed. The effects of thermal buoyancy strength on the fluid motion and temperature are also illustrated. It was found that the heat transfer rate of cylinders depends significantly on the position inside the enclosure. Moreover, the role of Prandtl number on flow and thermal patterns is negligible. The values of Nusselt number are also given, which can be useful for some engineering applications.
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