Regulations to reduce greenhouse gas emissions of passenger vehicles are becoming increasingly stringent. The aerodynamic drag is a major contributor to the vehicle’s total energy consumption where a large portion is attributed to the base wake. This paper optimises the angles of small trailing edge flaps on a base cavity of a full-scale sports utility vehicle placed in a wind tunnel. The trailing edge flaps are controlled using servos mounted inside the cavity. The flap angles are optimised using a surrogate model based optimisation algorithm with the objective of reducing the aerodynamic drag at different yaw angles and to create a yaw-insensitive geometry by considering several weighted yaw angles to form the driving cycle averaged drag. Low drag designs are further investigated using base pressures and wake measurements. The results show that the base pressures are symmetrised by reducing the crossflow in the wake. As the model is yawed the wake becomes increasingly downwash dominated by a large rotating windward structure which is reduced by the optimised flaps. The cycle averaged drag optimised design has a smaller increase in drag when yawed compared to a design optimised without considering yaw.

减少乘用车温室气体排放的法规越来越严格。空气动力阻力是车辆总能量消耗的主要贡献者，其中很大一部分归因于底部尾流。本文优化了放置在风洞中的全尺寸运动型多功能车底座腔上的小后缘襟翼的角度。使用安装在空腔内的伺服系统控制后缘襟翼。襟翼角度使用基于代理模型的优化算法进行优化，目的是减少不同偏航角下的空气动力阻力，并通过考虑几个加权偏航角来创建偏航不敏感的几何形状，以形成行驶周期平均阻力。使用基础压力和尾流测量进一步研究低阻力设计。结果表明，通过减少尾流中的横流，基础压力是对称的。随着模型的偏航，尾流变得越来越多地由一个大型旋转迎风结构主导，该结构被优化的襟翼减少。与不考虑偏航的优化设计相比，循环平均阻力优化设计在偏航时的阻力增加较小。