الفهرس 
NUMERICAL SIMULATIONSOnly 14 pages are availabe for public view
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Abstract
Air distribution system is a basic component of the Environmental Control System (ECS) of passenger aircraft and it should correctly distribute the air appropriately, cleaning up contaminated air and minimizing cross-airborne infection to provide a healthy and comfortable environment for passengers and crew. As aircraft operators have required to substantially reducing the fuel consumption by flying at higher altitudes, the energy cost for providing adequate outside air for ventilation has increased, which has led to a significant decrease in the amount of outside air provided to the passenger cabin. Consequently efficient fresh air delivery has become an important research issue in the field of aircraft ventilation To improve the air distribution system used in the existing aircraft cabins, two different case studies are investigated numerically by means of Computational Fluid Dynamics (CFD) approach with ANSYS-FLUENT solver. To ensure the simulation results are representative of the physical condition, the CFD model is first validated and the numerical results are compared with the experimental data. A typical Boeing 767-300 commercial aircraft cabin is selected since a quantitative data is available from an experimental study for the same domain. Then the validated CFD model is used to predict the distributions of the air velocity, air temperature, and CO2 concentration in the aircraft cabin for the two roposed case studies The first case proposed that the fresh air is supplied into the aircraft cabin at six different air inlet directions of A, B, C, D, E & F that correspond to the inlet angles of (0°, 180°), (355°, 185°), (350°, 190°), (340°, 200°), (330°, 210°), (315°, 225°) respectively. The simulation results showed that the flow pattern, temperature and CO2 levels are improved significantly inside the aircraft cabin in case of changing the air inlet supply angle. The performance of mixing-air distribution system for the whole aircraft cabin is enhanced remarkably with directions A, B and C. Furthermore, directions B and C provided the best ventilation performance among the six proposed directions within both cabin and local passengers’ breathing zones in terms of thermal and health comfort. The numerical results of direction B showed high constancy and stability in flow field, temperature and CO2 level in the whole cabin and at the local breathing zones compared to direction C.In the second proposed case study, transient simulations were conducted on the three dimensional model. Three rates of inlet flow were investigated in this design of 100% steady, 110% periodic and 120% periodic. The inlet velocity with periodic air inlet supply conditions is set to follow a square wave signal and the fresh air jet is oscillating for an interval of time after entering the aircraft cabin. One hundred and twenty seconds (120s) interval length was examined for the two periodic flow rates, (80s) as a duty period (high flow rate) and (40s) as an idle period (low flow rate), which could be defined as the period between two sequentially duty periods. The total amount of air supplied during the interval was the same as that of the steady rate in order to evaluate the two periodic flow rates by comparing against the steady flow rate. Numerical results showed that the periodic supply conditions produce better ventilation and relative reduction in fuel consumption could be achieved which leads to higher engine performance rather than steady supply conditions.