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Aerodynamic drag reduction by means of platooning configurations of light commercial vehicles: A flow field analysis
International Journal of Heat and Fluid Flow ( IF 2.6 ) Pub Date : 2021-06-11 , DOI: 10.1016/j.ijheatfluidflow.2021.108823
J.J. Cerutti , G. Cafiero , G. Iuso

Platooning configurations of two, three and four commercial vehicles were tested at a Reynolds number based on the vehicle’s length (L) of230000. The platoon configurations were obtained using an instrumented model, and three wooden replicas located at different positions with respect to the instrumented one. The reference model presents a slant angle at the leading edge, which can produce, in principle, a significantly different flow field compared to the generally studied Ahmed body. Drag, static pressure distributions and pressure fluctuations measurements were carried out. Additionally, planar PIV measurements were performed to investigate the near wake of the two-vehicles platoon configuration.

For the two-models platoon, drag reductions of 30% and 43% were evidenced for the front and for the rear vehicle, respectively, at an inter-vehicle distance (d) equal to half the vehicle’s length, and corresponding to an average drag reduction of 36.5%. For increasing distance, the benefit associated with the platooning configuration reduces, reaching an average drag reduction of 20% atd/L = 3. We relate the vehicle’s drag to the flow field organization and to the distribution of the modal energy through Proper Orthogonal Decomposition of the microphonic probes located on the base of the instrumented vehicle. We also evidence that the key element that is responsible for the pumping of the wake is the large vortex that generates near the top edge of the vehicle’s base.

We show that the slant angle does not affect the drag reduction of the leading vehicle of the platoon, whereas it can lead to larger differences in the case of the rear vehicle.

For three and four-vehicles platoons, consistently larger values of the average drag reduction are experienced (35%) and were also obtained for distances >1L. A simple model describing the overall drag reduction for a generic number of vehicles is presented and discussed.



中文翻译:

通过轻型商用车的队列配置减少气动阻力:流场分析

两辆、三辆和四辆商用车的编队配置以基于车辆长度的雷诺数进行测试() 的230000. 排配置是使用仪器模型获得的,三个木制复制品位于相对于仪器模型的不同位置。参考模型在前缘呈现一个倾斜角,与通常研究的 Ahmed 体相比,原则上可以产生明显不同的流场。进行了阻力、静压分布和压力波动测量。此外,还进行了平面 PIV 测量以研究两辆车排配置的近尾迹。

对于两个模型排,前车和后车的阻力分别降低了 30% 和 43%,在车辆间距离(d) 等于车辆长度的一半,相当于平均减阻 36.5%。随着距离的增加,与编队配置相关的好处会减少,在 20% 的平均阻力减少d/ = 3. 我们将车辆的阻力与流场组织和模态能量的分布联系起来,通过位于仪表车辆底部的麦克风探头的适当正交分解。我们还证明,负责泵送尾流的关键因素是在车辆底部顶部边缘附近产生的大涡流。

我们表明,倾斜角不会影响排前车的减阻,而在后车的情况下,它会导致更大的差异。

对于三车和四车排,平均减阻值持续较大(35%) 并且也是在距离 >1 时获得的. 介绍和讨论了一个简单的模型,描述了一般数量的车辆的整体减阻效果。

更新日期:2021-06-13
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