Bouabdellah Abed - Academia.edu (original) (raw)

Uploads

Papers by Bouabdellah Abed

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

Realizing the growing importance and availability of motor vehicles, we observe that the main sou... more Realizing the growing importance and availability of motor vehicles, we observe that the main source of pollution in the street canyons comes from the dispersion of automobile engine exhaust gas. It represents a substantial effect on the micro-climate conditions in urban areas. Seven idealized-2D building configurations are investigated by numerical simulations. The turbulent Schmidt number is introduced in the pollutant transport equation in order the take into account the proportion between the rate of momentum turbulent transport and the mass turbulent transport by diffusion. In the present paper, we attempt to approach the experimental test results by adjusting the values of turbulent Schmidt number to its corresponding application. It was with interest that we established this link for achieving our objectives, since the numerical results agree well with the experimental ones. The CFD code ANSYS CFX, the k, e and the RNGk-e models of turbulence have been adopted for the resolut...

In this presented work, a numerical investigation was conducted to evaluate the performance of RA... more In this presented work, a numerical investigation was conducted to evaluate the performance of RANS turbulence models implemented in ANSYS CFX to predict flow field and aerodynamic characteristics of the NREL S809 Airfoil. The simulations were carried out with ANSYS CFX R18.2 (academic version). The blade geometry was simplified into a 2D airfoil and the flow analysis around the profile was conducted at various angles of attack equal to 0°, 5.13°, 9.22°, 11.24° and 20.15°, at a constant and same Reynolds number equal to 2x106. In this paper, the turbulence flow patterns and separation around the profile were represented using the most turbulence models used in CFD codes, the standard k-e and its modifications RNG k-e. The moment coefficient (Cm), the lift coefficient (Cl) and the drag coefficient (Cd) were determined and plotted as a function of the angle of attack. The pressure distributions around this profile, for each angle of attack, were also presented. The results and the plo...

International Journal of Renewable Energy Research, 2017

In the field of renewable energy, a growing attention is given to cross flow turbine such as the ... more In the field of renewable energy, a growing attention is given to cross flow turbine such as the Darrieus turbine. This turbine, originally used as a wind turbine, is currently used as a water turbine to extract energy from water currents, reservoirs, rivers and oceans to eventually convert into electrical energy. In the work presented in this paper a series of painstaking experiments, for different velocity of the water flow (V = 0.37 m/s to 0.73 m/s), was conducted (at the Hydro-Pneumatic Power Laboratory of Northeastern University, Boston, USA) to determine the influence of this velocity on the performance parameters of a water Darrieus turbine, such as torque, mechanical power and power coefficient. The experimental model of the water Darrieus turbine has three NACA0020 blades with a length of 0.216 m, a chord of 0.069 m and a solidity of 2. These blades are fixed at a radius of 0.104 m and an offset angle of 120°. The main finding from the results analysis, obtained with a good...

Determination of hydrodynamic forces acting on the blades of Darrieus turbine used to harness wat... more Determination of hydrodynamic forces acting on the blades of Darrieus turbine used to harness water energy from dams, rivers and ocean is very important to evaluate this turbine performance. Therefore, this paper presents the numerical results of CFD investigation using K-e closure turbulence model. This simulation has been performed for a hydro Darrieus turbine that we have previously tested experimentally; this turbine has a diameter of 21.5 cm and it is composed of three NACA0020 blades, with a height of 23 cm and a cord of 7 cm, that are fixed with a separation angle of 120 °. The present simulation has been carried out for a water flow velocity of 0.67 m/s and the Darrieus turbine rotating velocity of 125 rpm. These values correspond to a specific velocity λ equal to 2, a flow Reynolds number Rev equal to 4.57 104, a rotational Reynolds number Reu equal to 1.97 105 and a relative Reynolds number Rew varying between 4.72 104 and 1.39 105. The graphical presentations of the simul...

Efficiency and power improvement of cross-flow turbines harnessing rivers and ocean water energy ... more Efficiency and power improvement of cross-flow turbines harnessing rivers and ocean water energy is a key issue. Therefore, in this paper, w e present the results of an experimental investigation on the effects of the blades orientation on a cross-flow water turbine performance. Four similar test models ( same dimensions and blades ) bur for different blades orientation angle i = 1.75 °, 4.5 °, - 1.75 ° and - 4.5 ° have been tested to evaluate the performance of this vertical axis water turbine (VAWT) , for several water flow velocities V varying from 0.3 to 0.59 m/s, which correspond to a water free flow Reynolds number of 2.08 10 4 to 4.36 10 4 . An analysis of these experimental results has shown that the best performance (biggest power and power coefficient) was obtained for the test model with its blades orientation angle set to 1.75 ° and the worst performance was given for the test model blades orientation of -4.5 °. A comparison of the present results with those obtained in ...

World Academy of Science, Engineering and Technology, International Journal of Environmental and Ecological Engineering, 2016

In the present work, a 2D numerical study, using the k-ε Standard and k-ε EARSM turbulence models... more In the present work, a 2D numerical study, using the k-ε Standard and k-ε EARSM turbulence models, has been carried out to determine which turbulence model better predicts the performance of the experimental Darrieus turbine test model. The computational fluid dynamics (CFD) was done for a vertical water Darrieus turbine (VAHT), with three NACA0020 straight blades, rotating at five different RPM (96, 115, 145, 175 and 215 rpm) in a closed duct and water flowing at V = 0.55 m/s. At first, a grid analysis for three different grid sizes has been carried out to determine the minimum one required to ensure a good and acceptable prediction of the performance of this turbine test model. Then, the determined numerical forces results were used to calculate the torque, mechanical power and torque and power coefficients. The comparison of these results with the experimental ones has shown, after a detailed analysis, that overall the k-ε Standard turbulence model ensure a better performance pre...

The objective of our work is to analyze numerically in three dimensions by the finite element met... more The objective of our work is to analyze numerically in three dimensions by the finite element method of the effect of a mechanical load on the delamination of unidirectional and multidirectional stratified composites in order to determine the energy release rate G in Mode I and the Von Mises equivalent stress distribution along the damaged area under the influence of several parameters such as applied load and delamination size. The results obtained in this study show that unidirectional composite laminates have better mechanical strength on the loading line than multi-directional composite laminates.

This paper presents a numerical analysis on the effect of turbulent Schmidt number on numerical p... more This paper presents a numerical analysis on the effect of turbulent Schmidt number on numerical prediction of pollutant dispersion within street canyons. Four cases of idealised-2D street canyons were simulated with several modifications to buildings geometry. The k – e and RNG k – e turbulence closure models have been adopted for turbulence modeling and the accuracy of numerical predictions has been examined by comparing calculated results with the available wind-tunnel measurements. The simulation results showed that the turbulent Schmidt number is a range of 0.1 to 1.3 that has some effect on the prediction of pollutant dispersion in the street canyons. For each street canyon configuration, an optimum value for turbulent Schmidt number was determined which gives good agreement with the experimental results. In the case of a flat roof canyon configuration (case-00), appropriate turbulent Schmidt number of 0.6 is estimated using the k – e model and of 0.5 using the RNG k – e .

International Journal of Energy Research

Wind and Structures, 2016

In the field of renewable energy, a growing attention is given to cross flow turbines such as the... more In the field of renewable energy, a growing attention is given to cross flow turbines such as the Darrieus turbine. This turbine, originally used as a wind turbine, is currently used as a water turbine to extract mechanical energy from water currents, reservoirs, rivers and oceans to eventually convert into electrical energy. In the work presented in this paper a series of painstaking experiments, for different velocity of the water flow from V = 0.37 m/s to 0.73 m/s, was conducted (at the Hydro-Pneumatic Power Laboratory of Northeastern University, Boston, USA) to determine the influence of this velocity on the performance parameters of a water Darrieus turbine, such as torque, mechanical power and power coefficient. The experimental model of the water Darrieus turbine has three NACA0020 blades with a length of 0.216 m, a chord of 0.069 m and a solidity of 2. These blades are fixed at a radius of 0.104 m and an offset angle of 120°. The main finding from the results analysis, obtained with a good consistency, is the increase of the water flow velocity from 0.37 m/s to 0.73 m/s (corresponding relative Reynolds number from 3.5 10 4 to 2.8 10 5) causes an increase in torque, power and power coefficient generated by this turbine model respectively from 0.17 Nm to 0.75 Nm, from 1.66 W to 11.67 W and from 16.92 % to 31.77 %, which gives a 604 % power relative increase for a water velocity relative increase equal to 100 %.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

Realizing the growing importance and availability of motor vehicles, we observe that the main sou... more Realizing the growing importance and availability of motor vehicles, we observe that the main source of pollution in the street canyons comes from the dispersion of automobile engine exhaust gas. It represents a substantial effect on the micro-climate conditions in urban areas. Seven idealized-2D building configurations are investigated by numerical simulations. The turbulent Schmidt number is introduced in the pollutant transport equation in order the take into account the proportion between the rate of momentum turbulent transport and the mass turbulent transport by diffusion. In the present paper, we attempt to approach the experimental test results by adjusting the values of turbulent Schmidt number to its corresponding application. It was with interest that we established this link for achieving our objectives, since the numerical results agree well with the experimental ones. The CFD code ANSYS CFX, the k, e and the RNGk-e models of turbulence have been adopted for the resolut...

In this presented work, a numerical investigation was conducted to evaluate the performance of RA... more In this presented work, a numerical investigation was conducted to evaluate the performance of RANS turbulence models implemented in ANSYS CFX to predict flow field and aerodynamic characteristics of the NREL S809 Airfoil. The simulations were carried out with ANSYS CFX R18.2 (academic version). The blade geometry was simplified into a 2D airfoil and the flow analysis around the profile was conducted at various angles of attack equal to 0°, 5.13°, 9.22°, 11.24° and 20.15°, at a constant and same Reynolds number equal to 2x106. In this paper, the turbulence flow patterns and separation around the profile were represented using the most turbulence models used in CFD codes, the standard k-e and its modifications RNG k-e. The moment coefficient (Cm), the lift coefficient (Cl) and the drag coefficient (Cd) were determined and plotted as a function of the angle of attack. The pressure distributions around this profile, for each angle of attack, were also presented. The results and the plo...

International Journal of Renewable Energy Research, 2017

In the field of renewable energy, a growing attention is given to cross flow turbine such as the ... more In the field of renewable energy, a growing attention is given to cross flow turbine such as the Darrieus turbine. This turbine, originally used as a wind turbine, is currently used as a water turbine to extract energy from water currents, reservoirs, rivers and oceans to eventually convert into electrical energy. In the work presented in this paper a series of painstaking experiments, for different velocity of the water flow (V = 0.37 m/s to 0.73 m/s), was conducted (at the Hydro-Pneumatic Power Laboratory of Northeastern University, Boston, USA) to determine the influence of this velocity on the performance parameters of a water Darrieus turbine, such as torque, mechanical power and power coefficient. The experimental model of the water Darrieus turbine has three NACA0020 blades with a length of 0.216 m, a chord of 0.069 m and a solidity of 2. These blades are fixed at a radius of 0.104 m and an offset angle of 120°. The main finding from the results analysis, obtained with a good...

Determination of hydrodynamic forces acting on the blades of Darrieus turbine used to harness wat... more Determination of hydrodynamic forces acting on the blades of Darrieus turbine used to harness water energy from dams, rivers and ocean is very important to evaluate this turbine performance. Therefore, this paper presents the numerical results of CFD investigation using K-e closure turbulence model. This simulation has been performed for a hydro Darrieus turbine that we have previously tested experimentally; this turbine has a diameter of 21.5 cm and it is composed of three NACA0020 blades, with a height of 23 cm and a cord of 7 cm, that are fixed with a separation angle of 120 °. The present simulation has been carried out for a water flow velocity of 0.67 m/s and the Darrieus turbine rotating velocity of 125 rpm. These values correspond to a specific velocity λ equal to 2, a flow Reynolds number Rev equal to 4.57 104, a rotational Reynolds number Reu equal to 1.97 105 and a relative Reynolds number Rew varying between 4.72 104 and 1.39 105. The graphical presentations of the simul...

Efficiency and power improvement of cross-flow turbines harnessing rivers and ocean water energy ... more Efficiency and power improvement of cross-flow turbines harnessing rivers and ocean water energy is a key issue. Therefore, in this paper, w e present the results of an experimental investigation on the effects of the blades orientation on a cross-flow water turbine performance. Four similar test models ( same dimensions and blades ) bur for different blades orientation angle i = 1.75 °, 4.5 °, - 1.75 ° and - 4.5 ° have been tested to evaluate the performance of this vertical axis water turbine (VAWT) , for several water flow velocities V varying from 0.3 to 0.59 m/s, which correspond to a water free flow Reynolds number of 2.08 10 4 to 4.36 10 4 . An analysis of these experimental results has shown that the best performance (biggest power and power coefficient) was obtained for the test model with its blades orientation angle set to 1.75 ° and the worst performance was given for the test model blades orientation of -4.5 °. A comparison of the present results with those obtained in ...

World Academy of Science, Engineering and Technology, International Journal of Environmental and Ecological Engineering, 2016

In the present work, a 2D numerical study, using the k-ε Standard and k-ε EARSM turbulence models... more In the present work, a 2D numerical study, using the k-ε Standard and k-ε EARSM turbulence models, has been carried out to determine which turbulence model better predicts the performance of the experimental Darrieus turbine test model. The computational fluid dynamics (CFD) was done for a vertical water Darrieus turbine (VAHT), with three NACA0020 straight blades, rotating at five different RPM (96, 115, 145, 175 and 215 rpm) in a closed duct and water flowing at V = 0.55 m/s. At first, a grid analysis for three different grid sizes has been carried out to determine the minimum one required to ensure a good and acceptable prediction of the performance of this turbine test model. Then, the determined numerical forces results were used to calculate the torque, mechanical power and torque and power coefficients. The comparison of these results with the experimental ones has shown, after a detailed analysis, that overall the k-ε Standard turbulence model ensure a better performance pre...

The objective of our work is to analyze numerically in three dimensions by the finite element met... more The objective of our work is to analyze numerically in three dimensions by the finite element method of the effect of a mechanical load on the delamination of unidirectional and multidirectional stratified composites in order to determine the energy release rate G in Mode I and the Von Mises equivalent stress distribution along the damaged area under the influence of several parameters such as applied load and delamination size. The results obtained in this study show that unidirectional composite laminates have better mechanical strength on the loading line than multi-directional composite laminates.

This paper presents a numerical analysis on the effect of turbulent Schmidt number on numerical p... more This paper presents a numerical analysis on the effect of turbulent Schmidt number on numerical prediction of pollutant dispersion within street canyons. Four cases of idealised-2D street canyons were simulated with several modifications to buildings geometry. The k – e and RNG k – e turbulence closure models have been adopted for turbulence modeling and the accuracy of numerical predictions has been examined by comparing calculated results with the available wind-tunnel measurements. The simulation results showed that the turbulent Schmidt number is a range of 0.1 to 1.3 that has some effect on the prediction of pollutant dispersion in the street canyons. For each street canyon configuration, an optimum value for turbulent Schmidt number was determined which gives good agreement with the experimental results. In the case of a flat roof canyon configuration (case-00), appropriate turbulent Schmidt number of 0.6 is estimated using the k – e model and of 0.5 using the RNG k – e .

International Journal of Energy Research

Wind and Structures, 2016

In the field of renewable energy, a growing attention is given to cross flow turbines such as the... more In the field of renewable energy, a growing attention is given to cross flow turbines such as the Darrieus turbine. This turbine, originally used as a wind turbine, is currently used as a water turbine to extract mechanical energy from water currents, reservoirs, rivers and oceans to eventually convert into electrical energy. In the work presented in this paper a series of painstaking experiments, for different velocity of the water flow from V = 0.37 m/s to 0.73 m/s, was conducted (at the Hydro-Pneumatic Power Laboratory of Northeastern University, Boston, USA) to determine the influence of this velocity on the performance parameters of a water Darrieus turbine, such as torque, mechanical power and power coefficient. The experimental model of the water Darrieus turbine has three NACA0020 blades with a length of 0.216 m, a chord of 0.069 m and a solidity of 2. These blades are fixed at a radius of 0.104 m and an offset angle of 120°. The main finding from the results analysis, obtained with a good consistency, is the increase of the water flow velocity from 0.37 m/s to 0.73 m/s (corresponding relative Reynolds number from 3.5 10 4 to 2.8 10 5) causes an increase in torque, power and power coefficient generated by this turbine model respectively from 0.17 Nm to 0.75 Nm, from 1.66 W to 11.67 W and from 16.92 % to 31.77 %, which gives a 604 % power relative increase for a water velocity relative increase equal to 100 %.