Modification des transferts de chaleur en convection naturelle par perturbation thermique localisée

Abstract : This thesis deals with the modifications of heat transfer and fluid flow in natural convection. The configuration chosen is a differentially heated cavity of aspect ratio equal to 4. The modifications are achieved using a small spatial extent disturbance located at the hot wall at a Rayleigh number value close of the critical value corresponding to the transition from steady to unsteady state. Two complementary studies were conducted. A preliminary numerical study was carried out, in which a thermal disturbance was introduced by means of a local change of the imposed temperature at the isothermal wall. It was shown that the flow regime can be changed from a steady state to an unsteady one. In addition, the heat transfers can be significantly modified by an appropriate choice of disturbance parameters (frequency, magnitude and location). An additional study, using an experimental device, was conducted by positioning a cylindrical obstacle on the hotwall. Two types of obstacles were chosen : insulating and conductive. The influence on heat transfers of the length of the obstacle, its vertical location, the Rayleigh number ofthe flow as well as the number of obstacles was analyzed in the vertical mid-depth plane.
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Paul Chorin. Modification des transferts de chaleur en convection naturelle par perturbation thermique localisée. Autre. ISAE-ENSMA Ecole Nationale Supérieure de Mécanique et d'Aérotechique - Poitiers, 2018. Français. ⟨NNT : 2018ESMA0021⟩. ⟨tel-02078817⟩

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