地铁列车尾部吹吸气控制对尾流特征的影响OA北大核心CSTPCD

In order to improve the flow characteristics at the rear of subway trains and reduce the aerodynamic resistance of trains,an active flow control method for blowing and inhaling air on the surface of the rear of subway trains was proposed.The changes in the flow field and aerodynamic resistance at the rear of the train in different blowing forms and speeds were analyzed,and the reasons for the changes in the aerodynamic performance of the train under the effect of blowing and suction at the rear of the train were explained.The results indicate that applying an active control method of blowing/inhaling in the tail car can achieve the goal of reducing the aerodynamic resistance of the train.At a blowing and suction speed of 0.6U(U is the train speed),the aerodynamic drag reduction effect of centralized blowing control is the most significant,with a aerodynamic drag reduction rate of 12.9%for the entire three-car formation,followed by non-centralized blowing at 10.9%,and suction control at 10.3%.The tail car blowing control effectively suppresses the flow vortex structure by disturbing the flow field,and compared to non-centralized blowing,centralized blowing with the airflow direction converging at a certain focal point can significantly improve aerodynamic drag reduction performance.The suction control reduces the aerodynamic drag of the entire vehicle by removing the flow vortices near the shoulder wall of the tail car,but the suction causes stronger flow acceleration,resulting in a decrease in the aerodynamic drag reduction effect.Therefore,it is recommended to use a centralized air blowing method with a speed of 0.6U to improve the aerodynamic resistance of blunt headed trains.At this air blowing speed,the reduction ratios of aerodynamic resistance in the front,middle,rear,and entire trains are 0.3%,4.5%,27.6%,and 12.9%,respectively.