不同雷诺数下车辆队列尾车发动机舱盖气动特性研究

数值仿真与模型风洞试验相结合研究了典型工况下两车队列中尾车发动机舱盖气动特性和两车间隔区域的流场,对比了缩比模型和实车模型对应雷诺数下车辆队列的流动形态。缩比模型仿真结果与风洞试验结果一致表明采用数值方法的可行。对比不同雷诺数下车辆队列气动特性发现,缩比模型与实车模型发动机舱盖表面平均静压分布基本相同,但在纵向对称面上,实车模型的前车尾迹比缩比模型更加上扬,底部区域气流速度更高。非定常条件下,实车模型前车尾涡相对尺度明显小于缩比模型,且扩散得更充分,尾迹区涡的分布状态更加混沌,发动机舱盖表面脉动能量的分布更加混乱。涡在两车间隔区域的运动并非简单的移动,而是一个由涡破裂、涡配对和涡融合构成的复杂过程。

Investigation into Bonnet Aerodynamic Characteristics of FollowerVehicle in Two-vehicle Platoon at Different Reynolds Numbers

The bonnet aerodynamic characteristics of follower vehicle and the flow field in the interspace between vehicles in a two-vehicle platoon are studied,and the flow patterns of scaled model and full scale vehicle model with corresponding Reynolds numbers for two-vehicle platoon are compared by both numerical simulation and model wind tunnel test.The results of simulation are consistent with wind tunnel test for the scaled model,indicating the feasibility of the numerical method adopted.The comparison of the aerodynamic characteristics of platoon at different Reynolds numbers shows that the average static pressure distribution on the bonnet surfaces for both the scaled model and full scale model are basically identical,but on the longitudinal symmetric plane,the tail trace of leading vehicle for full scale model is more up-wards with higher air-flow velocity in bottom area compared with the scaled model.Under unsteady condition and compared with the scaled model,the relative scale of tail vortex of leading vehicle for full scale model apparently smaller,its diffusion is more sufficient with more chaotic state of distribution,and the distribution of pulsating energy on bonnet surface is more disorderly.The movement of vortex in the interspace between vehicles is not a simple displacement but a complex process composed of breakup,pairing and fusing of vortex.