Browsing by Author "Mamo, Nigusie"

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    Aerodynamic Characteristics and Aerodynamic Shape Optimization of Ethiopian National Train, Case Study on Addis Ababa Dire Dawa Passenger Train
    (Addis Ababa University, 2014-10) Mamo, Nigusie; Demiss, Alemu (PhD)
    The aim of this study is to study and improve the aerodynamic performance (drag coefficient, lift coefficient, etc.), to reduce the energy consumption and checking the operational safety of the train against cross wind. The area of the study mainly concentrated on the frontal aerodynamic drag analysis and related characteristics of Ethiopian National Train (ENT).In particular Addis Ababa Dire Dawa 120 km/hr. speed passenger train is used for the analysis. The computational fluid dynamics (CFD) analysis simulation method is used for the study. To improve aerodynamic drag performance shape optimization of train head is done using multi-objective approximation integrated with computational fluid dynamics and response surface methodology. For the CFD full scale analysis ANSYS fluent 12.0 using steady RANS method is used. For the study of the stability against cross wind the wind with yaw angle -30 to 60 degree is analyzed. Results shows that the train has poor aerodynamic performance at this speed and shape which has around 0.93 drag coefficient. Also has poor performance against cross wind, hence care must be taken especially on the curves and embankment. After shape optimization drag coefficient of around 0.79 is obtained which is close to minimum recommended result (0.5).This result in reduction of more than 15% drag coefficient and this shows reduction in energy consumption.