The aim of this experiment was to analyze the interaction and the development of two flows in the rectangular confined cavity described in this paper. The first was a forced convective flow generated by injecting air at low temperatures inside the cavity in a horizontal direction through an opened area located in the cavity front. Inside this cavity, a natural convective plume was developed simultaneously. Different experimental techniques were used in order to describe either the mean and fluctuating air flow or the mean and fluctuating temperature field, and also to analyze the interaction between these two flows. Firstly, our set-up was validated with the free jet configuration: we obtained a well-known three-dimensional turbulent free jet. Without plume, analysis of the results showed that injection flow behavior corresponded to a characteristic 3D wall jet along the upper wall, with an 15400 injection Reynolds number. The Coanda effect maintained the jet along the upper wall. We determined the parameters of the main velocity law in relation to those detailed in the literature. After that, the main flow developed simultaneously in the longitudinal and vertical directions, so that a recirculation zone appeared. With the plume that developed over an obstacle, we observed that cold flow behavior changed, because of the combination of some of the main parameters: geometrical parameters, injection Reynolds number and temperature gradient between injected flow and plume. For example, with an injection Reynolds number equal to 15400, we measured the influence of the plume on the main flow through the changes in the dynamic and temperature profiles. Three regimes were obtained: the main flow was maintained and no natural convective plume was observed; the transitional regime was characterized by the main flow development along the obstacles, in spite of the development of the natural convective plumes; the natural convective flow modified the wall jet and unsteady classical natural convective “mushrooms” were observed. The topical results deal with the parametric study. We worked on a critical number characterizing the mixture of the jet and the plume. This number is defined as the ratio of the Grashof number to the Reynolds number of the mixture flow. When this critical value was exceeded, the natural convective plume was able to stop the inlet wall jet.

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