Emissions of greenhouse gasses from passenger vehicles is a concern globally. One of the factors that influence the vehicles energy consumption is the aerodynamic drag, continuing to be an active topic of interest. This work investigates the vehicle wake in relation to aerodynamic drag in steady crosswind conditions. The vehicle used is a modified version of the generic Windsor geometry with wheels and a rearward-facing base cavity with nine angled surfaces, or flaps, distributed at the trailing edge of the cavity along the roof and sides. A surrogate model-based optimisation algorithm was used to minimise the drag coefficient by optimising the angle of each flap individually. The experiments were performed in the Loughborough University Large Wind Tunnel. The time-averaged and unsteady results of both the base pressures and tomographic Particle Image Velocimetry indicate that the optimised flap angles improve drag primarily by altering the wake balance. This is achieved by reducing the strength of a large leeward side vortex, reducing the crossflow within the wake.

中文翻译：

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使用锥形腔和不对称襟翼改善偏航时方背飞行器的气动阻力

乘用车的温室气体排放是全球关注的问题。影响车辆能耗的因素之一是空气动力阻力，这一直是一个活跃的话题。这项工作研究了在稳定侧风条件下与空气动力阻力相关的车辆尾流。所使用的车辆是通用 Windsor 几何结构的改进版本，带有轮子和一个向后的基腔，带有九个倾斜表面或襟翼，沿着顶部和侧面分布在腔的后缘。使用基于替代模型的优化算法通过单独优化每个襟翼的角度来最小化阻力系数。实验在拉夫堡大学大型风洞中进行。基础压力和断层扫描粒子图像测速的时间平均和非稳态结果表明，优化的襟翼角度主要通过改变尾流平衡来改善阻力。这是通过降低大型背风侧涡流的强度，减少尾流内的横流来实现的。