Study of Dynamic Fields in an Enclosure with Two Openings Heated by a Cylindrical Heat Source

The objective of this work is to understand and predict the gas flows generated in an enclosure with an aspect ratio H/L= 0.83, having 02 openings located at the floor level and heated by a linear solid heat source. 02 enclosures Case 23 and Case 21 were studied. In these enclosures the openings are symmetrical and of the same sections. In the enclosure Case 23, the heat source is 3 mm above the floor and located at the position x+ = 0. In the enclosure Case 21, the heat source is at the position x+ = 0.24. The numerical computations of the velocity fields, pressure fields and mass flow rates will be carried out using the Direct Numerical Simulation (DNS) method and considering that a constant temperature is initially imposed on the heat source, that the enclosure is in thermal equilibrium with the outside and that there is no movement of gases at the openings. The results show that in the Case 23 enclosure, the velocity plume is turbulent and centered while in the Case 21 enclosure the velocity plume is strongly deflected near the side wall located at x+ = 0.5. This deviation can be due to the Couanda effect. In the Case 23 and Case 21 enclosures, we observe on each opening an incoming mass flow of fresh air and an outgoing mass flow of hot gases. Part of the hot gas flows descending towards the floor of the enclosures exits the enclosure and the other part is entrained by the velocity plume. The numerical computations of differential static pressure show that near the floor the values of differential static pressure are negative and outside the vicinity of the floor they are positive and increase with the height of the enclosure. The static pressure profiles have the same appearance. The comparisons of the static pressure profiles obtained in the Case 23 enclosure with the results of the literature are consistent.