The aerodynamic characteristics of the van-body truck were studied by means of theoretical analysis, numerical simu-lation and wind tunnel experiments. The concept of critical length was presented for the van-body truck in wind tunnel experiments, the proper critical Reynolds number was found and the effects of ground parameters in ground effect simulation on the aerodynamic measure-ments were examined. It shows that two structure parameters, van height and the gap between the cab and the van, can obviously influ-ence the aerodynamic characteristics, and the additional aerodynamic devices, the wind deflector and the vortex regulator in the rear, can considerably reduce the aerodynamic drag of the van-body truck. Numerical simulations provided rich information of the flow fields around the van-body trucks.

论述了在1m量级风洞中进行汽车模型实验的有关技术问题，分析了厢式货车安装导流罩等气动附件后，气动阻力特性的变化情况，为在小风洞中进行汽车模型实验开辟了一条路径，为减小厢式货车的气动阻力提供了行之有效的方法。

工科流体力学课程教学存在教材经（古）典理论偏多、部分内容起点低、片面强调为专业服务、教学方法手段单调和师资队伍不稳定的问题；必须采取措施稳定师资队伍、转变教学思想和观念、调整教材体系和内容、更新实验内容。

In this paper, the differences in the characteris-tics of airflow around the van-body truck and of the aerodynamic drag, which were caused by the installation of a wind deflector, were studied by experimentally and numerically. The results show that after the installation of the deflector, the airflow around the top and bottom of the truck becoms smooth, the in-tensity of tail-vortex is weakened and its contribution area less-ened. It also indicates that the aerodynamic characteristics of the airflow are changed distinctly and the aerodynamic drag is re-duced considerably. The effect of the thin-wall deflector is better than the solid one in decreasing the drag. It is also concluded that proper design of the gap between the deflector bottom and the top of the driver cab can enhance the effect of the deflector in reduc-ing drag.

本文首次用三维数值模拟计算的方法结合风洞实验研究了厢式货车表面气流的流动特性。揭示了气流流动特性和厢式货车气动阻力特性之间的关系；厢式货车基本结构参数变化时阻力特性的变化规律。为厢式货车的气动造型设计提供了重要参考依据。