The phenomenon of shock/shock interaction(SSI)is widely observed in high-speed flow,and the double wedge SSI represents one of the typical problems encountered.The control effect of single-pulse plasma synthetic jet(P...The phenomenon of shock/shock interaction(SSI)is widely observed in high-speed flow,and the double wedge SSI represents one of the typical problems encountered.The control effect of single-pulse plasma synthetic jet(PSJ)on double wedge type-Ⅵand type-ⅤSSI was investigated experimentally and numerically,and the influence of discharge energy was also explored.The findings indicate that the interaction between PSJ and the high-speed freestream results in the formation of a plasma layer and a jet shock,which collectively governs the control of SSI.The control mechanism of single-pulse PSJ on SSI lies in its capacity to attenuate both shock and SSI.For type-ⅥSSI,the original second-wedge oblique shock is eliminated under the control of PSJ,resulting in a new type-ⅥSSI formed by the jet shock and the first-wedge oblique shock.For type-ⅤSSI,the presence of PSJ effectively mitigates the intensity of Mach stem,supersonic jet,and reflected shocks,thereby facilitating its transition into type-ⅥSSI.The numerical results indicate that the peak pressure can be reduced by approximately 32.26%at maximum.Furthermore,the development of PSJ also extends in the Z direction.The pressure decreases in the area affected by both PSJ and jet shock due to the attenuation of the SSI zone.With increasing discharge energy,the control effect of PSJ on SSI is gradually enhanced.展开更多
Efficiency and safety are paramount concerns for commuters, operators, and designers in subway stations. This study conducted controlled experiments and developed a modified force-based model to investigate the dynami...Efficiency and safety are paramount concerns for commuters, operators, and designers in subway stations. This study conducted controlled experiments and developed a modified force-based model to investigate the dynamics of pedestrian counterflow at bottlenecks, utilizing subway passenger alighting and boarding as a case study. Specifically, the efficiency and safety of three distinct movement modes: the cooperative mode(Coop), the combination of cooperative and competitive mode(C & C), and the competitive mode(Comp), were examined and compared. The experimental findings revealed that the C & C mode exhibited a clear lane formation phenomenon and demonstrated a higher flow rate than the Comp and Coop modes. This observation suggests that a combination of cooperative and competitive behaviors among pedestrians can positively enhance traffic efficiency and safety during the alighting and boarding process. In contrast, pedestrians exhibited increased detouring in their paths and more fluctuating trajectories in the Comp mode. Additionally, a questionnaire survey assessing the level of competition and cooperation among pedestrians provided a comprehensive analysis of the psychological dynamics of passengers during the alighting and boarding activities. Lastly, the proposed force-based model was calibrated and validated, demonstrating a good performance in accurately replicating the overall characteristics of the experimental process. Overall, this study offers valuable insights into enhancing the pedestrian traffic efficiency and safety within subway systems.展开更多
基金supported by the Independent Innovation Science Fund of National University of Defense Technology(No.24-ZZCX-BC-05)National Natural Science Foundation of China(Nos.92271110 and 12202488)+2 种基金the Major National Science and Technology Project(No.J2019-Ⅲ0010-0054)the National Postdoctoral Researcher Program of China(No.GZB20230985)the Natural Science Program of National University of Defense Technology(No.ZK22-30)。
文摘The phenomenon of shock/shock interaction(SSI)is widely observed in high-speed flow,and the double wedge SSI represents one of the typical problems encountered.The control effect of single-pulse plasma synthetic jet(PSJ)on double wedge type-Ⅵand type-ⅤSSI was investigated experimentally and numerically,and the influence of discharge energy was also explored.The findings indicate that the interaction between PSJ and the high-speed freestream results in the formation of a plasma layer and a jet shock,which collectively governs the control of SSI.The control mechanism of single-pulse PSJ on SSI lies in its capacity to attenuate both shock and SSI.For type-ⅥSSI,the original second-wedge oblique shock is eliminated under the control of PSJ,resulting in a new type-ⅥSSI formed by the jet shock and the first-wedge oblique shock.For type-ⅤSSI,the presence of PSJ effectively mitigates the intensity of Mach stem,supersonic jet,and reflected shocks,thereby facilitating its transition into type-ⅥSSI.The numerical results indicate that the peak pressure can be reduced by approximately 32.26%at maximum.Furthermore,the development of PSJ also extends in the Z direction.The pressure decreases in the area affected by both PSJ and jet shock due to the attenuation of the SSI zone.With increasing discharge energy,the control effect of PSJ on SSI is gradually enhanced.
基金Project supported by the National Natural Science Foundation of China (Grant No. 72301184)the Natural Science Foundation of Sichuan Province of China (Grant No. 2024NSFSC1073)the Fundamental Research Funds for the Central Universities (Grant No. YJ202329)。
文摘Efficiency and safety are paramount concerns for commuters, operators, and designers in subway stations. This study conducted controlled experiments and developed a modified force-based model to investigate the dynamics of pedestrian counterflow at bottlenecks, utilizing subway passenger alighting and boarding as a case study. Specifically, the efficiency and safety of three distinct movement modes: the cooperative mode(Coop), the combination of cooperative and competitive mode(C & C), and the competitive mode(Comp), were examined and compared. The experimental findings revealed that the C & C mode exhibited a clear lane formation phenomenon and demonstrated a higher flow rate than the Comp and Coop modes. This observation suggests that a combination of cooperative and competitive behaviors among pedestrians can positively enhance traffic efficiency and safety during the alighting and boarding process. In contrast, pedestrians exhibited increased detouring in their paths and more fluctuating trajectories in the Comp mode. Additionally, a questionnaire survey assessing the level of competition and cooperation among pedestrians provided a comprehensive analysis of the psychological dynamics of passengers during the alighting and boarding activities. Lastly, the proposed force-based model was calibrated and validated, demonstrating a good performance in accurately replicating the overall characteristics of the experimental process. Overall, this study offers valuable insights into enhancing the pedestrian traffic efficiency and safety within subway systems.
