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Theses

Etude de l'influence des paramètres du procédé de rotomoulage sur les caractéristiques aérodynamiques de fonctionnement d'un ventilateur axial.

Abstract : Plastic rotational molding is a manufacturing process developed in the 50’s. This approach possesses numerous advantages over others, such as processing, assembly, etc. One of the most noticeable benefits is the low cost of the subassembly manufacture. Noneover, it is commonly used today in various applied fields and still actively urges new research. This thesis focuses on turbomachinery, specifically cooling fans used in automobiles, an overheating industrial market. In the past, the preliminary versions of axial fans were designed and manufactured in the "Fluid Engineering and Energy Systems Laboratory" to meet this industrial needs. However, there has not been any practical research on the control and optimization of this manufacturing process. This thesis therefore fits naturally into a research dynamic making the link between the energy performance of the system and the manufacturing process.Resulting from the rotational molding process parameters, namely the mass of po- lymer powder, the temperature in the oven, and baking time, the general idea of the study lies in the interference of macroscopic scale with qualitative and quantitative analysis from the fan experiments. On one side, this would be geometry parameters, results of mechanical efficiency, etc. Besides, the output could act as the microscopic scale to identify the physical and chemical properties of the material. In other words, the thesis objective is to investigate the influence of the rotational molding process parameters in terms of the aerodynamic characteristics of axial fans.The experimental findings reveal significant differences in the aerodynamic efficiency of the fans. For instance, in a study in which 45 fans were tested, the energy efficiency difference is around 6%. Strikingly, these discripancies are strongly correlated with the mass of polymer powder used in manufacturing. In this study, we used polyethylene (PE). In order to clarify these differentiations, the first method was to ensure the quality control of the geometry of the manufactured part, especially at the level of the blades, like wedging, chord, and thickness, by 3D scanning methods. The results presented that there was little difference in varying the manufacturing parameters. However, thanks to the mechanical and physicochemical analysis of all the material samples, it was significant that for oven temperatures of 285°C and baking times for 15 minutes, the material degraded due to oxidation phenomena. Qualitatively, the fan was turning yellow; quantitatively, infrared spectroscopy revealed the apparent presence ofchemical bonds with oxygen.In addition, the mechanical analyzes on the material indicated the effect of the variation in temperature, the resistance modification of the material, as well as the Young’s modulus. The distribution of materials in the mold is of paramount impor- tance. With lower masses which is 300g, the dynamic unbalance phenomenon was less significant. As a consequence, the consumed mechanical power, therefore, went down, resulting in better efficiency. The visual appearance of the polymer distribution wi- thin the axial fan and the measurements utilizing an accelerometer made it possible to confirm this dispersion.In the light of the results, this thesis provides a better understanding of the be- havior of an axial turbomachine based on its manufacturing parameters. This work also contributes to opening up new research directions in the field of rotational mol- ding, in particular applied to automotive cooling fans, which is of great interest today.
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Submitted on : Tuesday, May 31, 2022 - 10:37:11 AM
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  • HAL Id : tel-03682543, version 1

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Vu Dinh Dang. Etude de l'influence des paramètres du procédé de rotomoulage sur les caractéristiques aérodynamiques de fonctionnement d'un ventilateur axial.. Mécanique des matériaux [physics.class-ph]. HESAM Université, 2021. Français. ⟨NNT : 2021HESAE048⟩. ⟨tel-03682543⟩

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