基于正交试验法的厢式货车气动减阻优化

为了优化某厢式货车的气动阻力系数,设计了驾驶室前部仿生减阻结构、顶部和侧部涡流发生器、底部涡流发生器等3种气动减阻装置。研究了3种单一气动减阻装置主要相关参数对气动阻力的影响,分别从货车外流场的速度轨迹、压力分布和湍动能分布等3方面详细分析了各单一气动减阻装置的减阻效果。在此基础上采用正交试验法对3种气动减阻装置的主要参数进行优化,获得最优减阻货车模型。研究表明:驾驶室前部突出部分的长度对货车整车气动阻力系数的影响比倾角更大;最优货车头部形状的倾角和长度分别为135°和300 mm,该模型的气动阻力系数为0.721 4,相对于货车原始模型的减阻率为8.93%;涡流发生器的高度和位置对货车的减阻效果均有较大的影响;涡流发生器可以增加货车尾部分离区流场的能量,使得尾涡区减小,气动压差阻力减小;3种气动减阻装置对货车气动阻力系数的影响大小依次为:底部涡流发生器、货车前部仿生减阻结构、顶部和侧部涡流发生器,其最优厢式货车模型的空气阻力系数为0.683 3,其复合减阻装置的最佳减阻率为13.8%。

Optimization of pneumatic drag reduction of van type truck based on orthogonal test method

In order to optimize the aerodynamic drag coefficient of a van type truck, three kinds of pneumatic drag reducing devices such as the bionic drag reduction structure of the front part of the cab, the top and side vortex generators, and the bottom vortex generator are designed. The effects of main parameters of three kinds of single pneumatic drag reducing devices on aerodynamic drag are studied. The drag reduction effect of each pneumatic drag reducing device is analyzed in detail from three aspects:speed trajectory, pressure distribution and turbulent kinetic energy distribution,on the basis of which, the main parameters of the three kinds of pneumatic drag reducing devices are optimized by orthogonal test method, and the truck model with optimal drag reduction is obtained. The research shows that the influence of the length of the front part of the cab on the aerodynamic drag coefficient of the truck is greater than that of the tilt angle. The inclination angle and length of the optimal truck head shape are 135ånd 300 mm, respectively. The aerodynamic drag coefficient of the model is 0.721 4, and the drag reduction rate is 8.93% compared with the original model of the truck. The height and position of the vortex generator have a great influence on the drag reduction effect of the truck. The vortex generator can increase the energy of the flow field in the separation area of the tail of the truck, and reduce the tail vortex area and the pneumatic differential pressure. The order of influence of the three kinds of pneumatic drag reducing devices on the aerodynamic drag coefficient of the truck is as follows:bottom vortex generator, the bionic drag reduction structure of the front part of the cab, and top and side vortex generators. The air drag coefficient of the optimal van type truck model is 0.683 3, and the optimal drag reduction rate of the composite drag reducing device is 13.8%.