Effet de l’ondulation de la surface sur le transfert de chaleur par jet impactant.

Abstract

The present work is a numerical simulation by the ANSYS Fluent code of a jet impinging on a surface fitted with square-shaped grooves. In the first part of this thesis, a parametric study on the flow dynamics and the heat transfer in an axisymmetric turbulent impinging jet is carried out using the SST k-ω turbulence model. Different parameters are varied: the groove size C, ranging from 0 to 1.5 (mm) (where C = 0 represents the smooth surface), the nozzleto-wall distance H/D ranging from 1 to 4, and the Reynolds number Re ranging from 5000 to 30000. The velocity, kinetic energy and temperature fields in the different regions of the domain and in particular inside the grooves are presented and discussed. The results show that an increase in the cavity size leads to an increase in friction and heat transfer. The comparison between the smooth wall and the corrugated walls shows that the latter improve the average Nusselt number by 80%, 82% and 85%, for the groove sizes 0.5, 1 and 1.5 mm respectively. Concerning the effect of the nozzle-to-target-surface distance the best heat transfer performance is obtained by using the small distance H/D = 1. As for the effect of the Reynolds number, the highest value of the Nusselt number obtained corresponds to the value of Re = 30000. In the second part of the work, the unsteady turbulent isothermal flow of a plane-in-the-mean semi-confined jet impinging on a surface fitted with square grooves is simulated using the LES approach. The configuration considered is such that the nozzle-towall distance H/L = 2, the cavity size C = 5 (mm) and the Reynolds number Re = 5000.