الفهرس 
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Abstract
Ventilation, which provides occupants with good indoor air quality and thermal comfort, has become an important sustainable strategy in building design such, as power stations, and nuclear reactors. This study aims to avoid the presence of hot spot that may cause serious effect. Three-dimensional air velocity and temperature distributions during the unsteady ventilation of a cubic room, with a heat source, as a simulation of a room around the reactor are investigated numerically and experimentally.
An unsteady turbulent and three-dimensional numerical model has been developed. Mac-Cormack 2-4 explicit numerical scheme which is a fourth-order accurate in space and second-order accurate in time is used to solve the basic equations. The Large Eddy Simulation (LES) model is used for turbulence. A Fortran program (LES) is designed to solve the three dimensional unsteady turbulent flow within the room. A validation of the mathematical model and the LES program is tested for two cases. Case one: for natural convection (no inlet air flow) where the present mathematical model is used and the results are compared with previous experiment. Case two: for forced ventilation with different inlet flow angles. Present numerical results are compared with present experimental values. The comparisons assure the soundness of both the numerical scheme and t he t urbulence model u sed. B oth s teady and unsteady flow fields are investigated numerically for different inlet and exit air locations.
Experimental facility is set up using hot wire anemometer for velocity measurement and eight thermocouples for temperature distribution measurements. Instrumentations allow the measurement of three- dimensional temperature profiles and one velocity component of airflow in the room. Finally it is found that by using the center of the middle third inlet air location, center oft he middle third o utlet a ir location and i nlet a ir flow angle of 120°, the temperature difference can be reduced 26 % than that for the worse case. The worst case for the cases considered in the present study is the case of using the center of the upper third inlet air location, the center of middle third exit air location and inlet flow angles of 90 °.
Effect of Archimedes number (Ar) is considered. Ar is varied by either changing the heat source temperature difference or changing the air reference velocity (maintaining the same air change rate). For small values of Ar, the forced convection dominates while larger values of Ar indicate that the natural convection has a major effect. Contours of numerically evaluated turbulent heat flux support this conclusion.