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This study numerically examines the behaviour of a two-dimensional turbulent flow of air in a rectangular pipe with three flat or corrugated baffles. A realizable k-ε turbulence model is used and the conservation equations are solved by the finite volume method using the SIMPLE algorithm. The study examined the dynamic and thermal behaviour of the flow by focusing on a presentation of several parameters, namely the turbulence intensity, the ratios of the friction coefficients and the Nusselt coefficients as well as the drag coefficients and thermal expansion, for all the geometry and for a Reynolds number varying from 5000 to 20000. The study showed that the presence of three baffles in a pipe governs a maximum turbulence intensity of the order of 206.49% to 110.72% for the small and the large inter-fin distance, which consequently guarantees a reinforcement of the heat exchange, of the order of 1.775 to 2.83 times compared with a smooth pipe, and on the other hand, an increase in friction with the walls of the order of 7 to 12 times. The study also revealed the existence of an optimum located between 0.14 and 0.16 m leading to the lowest friction ratio.

In the present paper, a numerical simulation has been carried out to determine the hydrodynamic characteristics in cavitating viscous flow of the conventional INSEAN E779A propeller in single and tandem configuration by using Singhal et al. cavitation model implemented in FLUENT Software. Firstly, calculations have been carried out on single E779A propeller in non-cavitating and cavitating flows. The computed performances have shown good agreement with experimental data. Next, the numerical approach has been applied in loaded conditions to the case of tandem propeller configurations with respectively 0.2 and 0.6 axial displacement. Results reveal that cavitation is qualitatively well predicted and the cavitation area is rather more pronounced on the fore propeller. Te use of tandem corotating propeller in loaded conditions is highlighted. [ABSTRACT FROM AUTHOR]

In the present paper, a numerical simulation based on Kω-SST turbulence model has been carried out to determine the tandem propeller hydrodynamic characteristics in noncavitating viscous flow by using the commercial code Fluent. As the first step, the numerical approach has been applied to the case of single propeller and the comparison with experiment results was in a good agreement. Next, the effects of axial and angular displacement as well as the diameter ratio between the tandem propellers have been investigated. This part of the study reveals that the tandem with idem propeller diameters is strongly recommended to assure more advantages. Furthermore, the tandem geometry corresponding to the axial displacement equal to 0.6D seems to be the best configuration and the open water performances remain almost unchanged with the variation of angular displacement. On the other hand, details of the mutual interaction between tandem propellers were also given by showing pressure contours, streamlines and thrust coefficient. Globally, this study illustrates the advantages of replacing single propellers by tandem solution. [ABSTRACT FROM AUTHOR]

The present paper deals with the effect of the geometric characteristics on the propeller hydrodynamic performances. Several propeller configurations are created by changing number of blades, expanded area and pitch ratios. The Reynolds-Averaged Navier-Stokes (RANS) equations are solved using the commercial code FLUENT 6.3.26. The standard k-ε and the k-ω SST models are used for the steady uniform and the transient non-uniform ship wake. Overlapping propellers arise from high expanded area involve that the computational domain should be created with several multi-blocks. Thrust, torque and efficiency coefficients of the generated propellers are compared with available experimental data. The computational results reveal that both standard k-ε and k-ω SST models guarantee acceptable level of accuracy in open water condition and unsteady flow predictions. This parametric study has also allowed achieving optimal shape factors ensuring best hydrodynamic performances. [ABSTRACT FROM AUTHOR]

In this paper, a new configuration of a horizontal axis wind turbine with three blades for domestic electricity production on farms was numerically simulated. Three configurations were tested numerically: a standard single-blade wind turbine (STWT), a single wind turbine (SWT), and a tandem three-blade wind turbine (TWT) for rural use. For the tandem wind turbine, the effects of pitch angle and the distance between the blades were also investigated. The Gambit and Fluent 19.2 codes were, respectively, used to generate different meshes and determine various parameters. The resolution of the averaged Navier–Stokes equations (RANS) using a finite volume method was conducted. The k–ε realizable two-equation model was chosen for turbulence calculation. The obtained results showed that the maximum power coefficient (Cp) was 0.444 for one of the tandem configurations (TWT), compared to the conventional blade (STWT). The maximum Cp obtained in this study is slightly greater than the experimental results found in the literature. It has also been observed that the flow on these new turbines exhibits a complex phenomenon on both surfaces. [ABSTRACT FROM AUTHOR]