الفهرس 
ACKNOWLEDGMENTOnly 14 pages are availabe for public view
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Abstract
The main purpose of tunnel ventilation is to provide enough fresh air Therefore, an optimal ventilation system is essential for underground mines and tunnels The system needs to be customized based on the specific conditions of the site such as the type of ore being extracted or the purpose of the tunnel The main goal of this thesis to improve the efficiency of tunnel ventilation in Cairo Metro Line No.3 which extends from Attaba station to Abbassia station and has a total length of 4.3 km This study has shown that the most significant natural factors affecting ventilation systems are determining the number location and function of fans to distribute the required fresh air flow at the lowest possible cost In this work the author’s try to solve these problems by 1) studying and calculating the ventilation rate (Q) and static head pressure (H) of Cairo Metro Line 3 under different conditions of ventilation design 2) selection of an economical design for less energy consumption and a high fan efficiency 3) Apply computational fluid dynamics (CFD) modeling using Ansys Fluent software for a numerical simulation of airflow distribution in the tunnel and calculate the required air flow in trains and stations 4) Compare the results with the actual data used by the National Authority for Tunnels (NAT) The results showed that one of the main tasks for selecting a suitable fan that meets the optimal design of an effective ventilation system is the ventilation rate Q and static pressure H. Both Q and H of Cairo Metro Line 3 were studied and calculated under different conditions of ventilation design from the data obtained from the National Authority for Tunnels According to the American Brattice Cloth (ABC) rigid duct tubing method the static head equals 1171.5 Pa, which is the most economical value that is gives the lower power consumption and rate of ventilation Applying CFD modelling has proved that 9.5 million cells provide acceptable accuracy for the fan speed (600 rpm) The required accuracy reaches 100 iterations, this demonstrates the accuracy of the solution resulting from the numerical analysis process saving time and energy in the solution The largest amount of air dispersion starts at the moment the train enters the tunnel and returns to normal after train departure This improves the performance of the fan, leading to low energy consumption The required air flow rate for trains and stations resulting from the investigation which has been calculated is acceptable when compared with the actual data from the NAT This result confirms that the predicted value using the program is almost the same as those from the NAT.