In this paper,the effects of a right-angle windbreak transition(RWT)from the flat ground to cutting on train aerodynamic and dynamic responses were investigated,then a mitigation measure,an oblique structure transitio...In this paper,the effects of a right-angle windbreak transition(RWT)from the flat ground to cutting on train aerodynamic and dynamic responses were investigated,then a mitigation measure,an oblique structure transition(OST)was proposed to reduce the impact of RWT on the train aerodynamic and dynamic performance.The results showed that in the RWT region,the airflow was divided into two parts.One part of the airflow induced a strong backflow in the flat ground position,and the other part of the airflow induced a strong backflow in the cutting position.Therefore,there were two lateral impacts on the train.For the head car with the OST,the drop ratios of the peak-to-peak values compared with RWT were 47%,40%,and 52%for the side force coefficient C_(Fy),lift force coefficient C_(Fz) and overturning moment coefficient C_(Mx),respectively.For the peak-to-peak value of the dynamic parameters,the drop ratios of OST compared with RWT were all larger than 50%.The maximum dynamic overturning coefficients for RWT and OST were 0.75 and 0.3,respectively.展开更多
Based on 3D, steady N-S equations and k-e turbulence model, Fluent was employed to do numerical simulation for lateral aerodynamic performance of 6-axis X2K double-deck container trains with two different loading form...Based on 3D, steady N-S equations and k-e turbulence model, Fluent was employed to do numerical simulation for lateral aerodynamic performance of 6-axis X2K double-deck container trains with two different loading forms, and speed limits of the freight trains were studied. The result indicates that under wind environment： 1） As for vehicles without and with cross-loaded structure, aero-pressure on the former is bigger, but air velocity around the latter is larger; 2） When sideslip angle θ=0°, the airflow is symmetry about train vertical axis; when θ〉0°, the airflow is detached at the top of vehicles, and the air velocity increases above the separated line but decreases below it; 3） With θ increasing, the lateral force on the mid vehicle firstly increases but decreases as θ=75°; 4） When the 6-axis X2K fiat car loads empty boxes of a 40 ft and a 48 ft at 120 km/h, the overturning wind speed is 25.19 m/s, and the train should be stopped under the 12th grade wind speed.展开更多
基金Project(2020YFA0710903)supported by the National Key R&D Program of ChinaProject(U1334205)supported by the National Natural Science Foundation of ChinaProject(1-W16W)supported by the Hong Kong Polytechnic University's Postdoc Matching Fund Scheme,China。
文摘In this paper,the effects of a right-angle windbreak transition(RWT)from the flat ground to cutting on train aerodynamic and dynamic responses were investigated,then a mitigation measure,an oblique structure transition(OST)was proposed to reduce the impact of RWT on the train aerodynamic and dynamic performance.The results showed that in the RWT region,the airflow was divided into two parts.One part of the airflow induced a strong backflow in the flat ground position,and the other part of the airflow induced a strong backflow in the cutting position.Therefore,there were two lateral impacts on the train.For the head car with the OST,the drop ratios of the peak-to-peak values compared with RWT were 47%,40%,and 52%for the side force coefficient C_(Fy),lift force coefficient C_(Fz) and overturning moment coefficient C_(Mx),respectively.For the peak-to-peak value of the dynamic parameters,the drop ratios of OST compared with RWT were all larger than 50%.The maximum dynamic overturning coefficients for RWT and OST were 0.75 and 0.3,respectively.
基金Project supported by Scholarship Award for Excellent Doctoral Student granted by Ministry of Education,ChinaProject(2012QNZT029) supported by the Fundamental Research Funds for the Central Universities of China+1 种基金Project(CX2010B122) supported by Hunan Provincial Innovation Foundation for Postgraduate,ChinaProject(2010ybfz088) supported by the Foundation of Excellent Doctoral Dissertation of Central South University,China
文摘Based on 3D, steady N-S equations and k-e turbulence model, Fluent was employed to do numerical simulation for lateral aerodynamic performance of 6-axis X2K double-deck container trains with two different loading forms, and speed limits of the freight trains were studied. The result indicates that under wind environment： 1） As for vehicles without and with cross-loaded structure, aero-pressure on the former is bigger, but air velocity around the latter is larger; 2） When sideslip angle θ=0°, the airflow is symmetry about train vertical axis; when θ〉0°, the airflow is detached at the top of vehicles, and the air velocity increases above the separated line but decreases below it; 3） With θ increasing, the lateral force on the mid vehicle firstly increases but decreases as θ=75°; 4） When the 6-axis X2K fiat car loads empty boxes of a 40 ft and a 48 ft at 120 km/h, the overturning wind speed is 25.19 m/s, and the train should be stopped under the 12th grade wind speed.
