队列中振荡的中间车辆
Oscillating Middle Vehicle in a Platoon
AI总结：
本文通过 CFD 瞬态模拟研究三车队列中中间车辆纵向振荡的阻力变化，发现稳态方法无法捕捉吸力和压缩等动态力，瞬态与稳态阻力差异可达约75%，并揭示了频率和间距对阻力振荡的影响。
摘要：
研究了一个由三个 Ahmed 车身组成的队列，以考察当中间成员失去同步并开始纵向振荡时阻力变化的影响。振荡在两个不同的缩减频率下进行，分别对应 NASCAR 中两种不同的跟车场景。通过计算流体动力学模拟计算了瞬态阻力，并与中间成员相对于前车和后车处于不同位置时获得的稳态平均阻力结果进行了比较。振荡会在队列中产生动态力，例如吸力和压缩力，这些力通过瞬态分析加以考虑。由于稳态工况无法再现振荡车辆上的这些力，中间车辆的稳态与瞬态阻力比较显示，在缩减频率为 0.4、归一化时间为 1.5 时，差异约为 75%。每个队列成员的阻力都会振荡，并在第一个周期后保持周期性可重复。更高的缩减频率会增加振荡成员的阻力幅值。对于队列中的其余成员，改变频率未显示出显著影响。在非常小的间距下，会发生压力损失，导致阻力突然变化。阻力峰值主要由动态力决定，因此应使用瞬态方法来研究队列中的振荡效应。
英文摘要：
A three-member platoon of Ahmed bodies was studied to investigate the effects of drag variation when the middle member goes out of synchronization and starts to oscillate longitudinally. Oscillations were carried out at two different reduced frequencies corresponding to two different drafting scenarios in NASCAR. Computational Fluid Dynamics simulations were performed to calculate the transient drag force, which was compared with the steady averaged drag results obtained with the middle member in different locations with respect to the lead and trailing bodies. Oscillations create dynamic forces in a platoon, such as suction and compression, which are taken into account by transient analysis. Since the steady cases failed to reproduce these forces on the oscillating vehicle, steady and transient drag comparison for the middle vehicle showed about 75\% difference at normalized time of 1.5 for reduced frequency of 0.4. Drag oscillates for every platoon member and remains cyclically repeatable after the first cycle. Higher reduced frequency increases the drag amplitude for the oscillating member. For the rest of the platoon, changing frequencies does not show significant effects. At very small separation gaps, pressure loss occurs resulting in sudden change in the drag. Drag peaks are mostly governed by the dynamic forces, therefore transient methods should be used for studying the oscillating effects in a platoon.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
