For using the swirling jet for air conditioning and heating in the premises, knowledge of the thermal characteristics is more than necessary. It is for this objective that the experimental and numerical study was realized. To conduct this study, we designed and built an experimental facility to ensure proper conditions of confinement in which we placed five air blowing devices with adjustable vanes, providing multiple swirling turbulent jet with a swirl number S = 0.4. The jets were issued in the same direction and the same spacing defined between them. This study concerned the numerical simulation of the thermal mixing of confined swirling multi-jets, and examined the influence of important parameters of a swirl diffuser system on the performance characteristics. The experimental measurements are also realized for a confined domain, aiming to determine the axial and radial temperature field. The CFD investigations are carried out by an unstructured mesh to discretize the computational domain. In this work, the simulations have been performed using the finite volume method and FLUENT solver, in which the standard k-ε, K-ε realizable, k-ε RNG and the RSM turbulence model were used for turbulence computations. The validation shows that the K-ε RNG model can be used to simulate this case successfully.
In this paper, a numerical simulation has been performed to study the fluid flow and heat transfer around a rotating circular cylinder over low Reynolds numbers. Here, the Reynolds number is 200, and the values of rotation rates (α) are varied within the range of 0 < α < 6. Two-dimensional and unsteady mass continuity, momentum, and energy equations have been discretized using the finite volume method. SIMPLE algorithm has been applied for solving the pressure linked equations. The effect of rotation rates (α) on fluid flow and heat transfer were investigated numerically. Also, time-averaged (lift and drag coefficients and Nusselt number) results were obtained and compared with the literature data. A good agreement was obtained for both the local and averaged values.
In this study we investigated the properties of the species diffusion layer (ADL) affect the optimal performance of the electrode [1]. Diffusion layers (DL) are porous media allowing reactive gases and liquids to move from distribution channels to catalyst layers (CC). Diffusion layers are an essential part of the PEM fuel cell and the porosity of these layers has a significant effect on the performance of the PEM fuel cell. The effects of diffusion layer porosity (ADL) on fuel cell performance are illustrated by the distribution curves of methanol and carbon dioxide at the anode, water and oxygen distribution at the cathode. and polarization curves.
This present work focused on new nozzles design method, based on the characteristics method, which is a technique method to reduce a partial differential equation to linear differential equations along which the solution can be integrated from initial conditions. The latter is developed under the real gas theory, because when the both pressure and temperature of a gas increases, the specific heat and their ratio do not remain constant anymore and start to vary with the gas parameters. The gas doesn’t stay perfect, and it becomes a real gas. The presented equations of the characteristics remain valid whatever area or field of study. With the assumptions that Berthelot’s state equation accounts for molecular size and intermolecular force effects, expressions are developed for analyzing the supersonic flow for thermally and calorically imperfect gas. The resolution has been made by the finite differences method using the corrector predictor algorithm. As result, the developed mathematical model used to design 2D minimum length nozzles under effect of the stagnation parameters of fluid flow. A comparison for air with the perfect gas PG and high temperature HT models on the one hand and our results by the real gas theory on the other of nozzles are made. An important gain of length and weight can rise up to 40% and 20% respectively. It is in this context that Minimum Length Nozzle (MLN) nozzles for aerospace engines based on real gas theory were developed to achieve maximum thrust with the smallest possible nozzle weight (minimum length).
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