侧风环境下减阻装置对重型货车气动特性的影响

Influence of Drag Reducing Device on Aerodynamic Characteristics of Heavy-duty Truck in Crosswind Environment

为了获得侧风环境下减阻装置对重型货车气动特性的影响,采用计算流体动力学方法研究了货车原始模型和加装封闭式仿生导流罩、尾部减阻装置、仿生非光滑表面3种新型气动减阻装置货车模型分别在无侧风和有侧风的11种工况下行驶的气动特性。结果表明:在无侧风和有侧风环境下,受海狮头部形状启发设计的封闭式仿生导流罩对货车具有显著的减阻效果,当横摆角为6°时导流罩模型相对于货车原始模型的减阻率为27.9%,但同时会增大货车的侧向力系数。尾部减阻装置在无侧风和有侧风环境下均具有较好的气动减阻效果,这是因为尾部减阻装置可以改善货车的尾部气流状态,而且该尾部减阻装置还能减少货车所受的侧向力,进而可以增加货车在侧风环境下的行驶稳定性和安全性;在有侧风环境下,非光滑表面结构的减阻效果有限,而且会增大货车所受侧向力。复合减阻装置在所有侧风工况下均具有显著的减阻效果,当横摆角为12°时,复合减阻装置具有最佳的减阻效果,其减阻率为68.8%;在横摆角位于0°~30°之间时,复合减阻装置的平均减阻率达到了37.3%。在侧风工况下,复合减阻装置会增大货车所受的侧向力,且横摆角增大,侧向力系数也急剧增大。

In order to obtain the influence of drag reducing device on aerodynamic characteristics of heavy-duty truck in crosswind environment,the aerodynamic characteristics of the original truck model and the truck model with 3 new aerodynamic drag reducing devices(closed bionic shroud,rear drag reduction device and bionic non-smooth surface)under 11 working conditions of with/without crosswind respectively are studied by using computational fluid dynamics.The result shows that(1)The closed bionic shroud,which is inspired by the shape of sea lion’s head,has significant drag reduction effect on the truck under the conditions of with/without crosswind.When the yaw angle is 6°,the drag reduction rate of the shroud model is 27.9%compared with the original model,but at the same time it will increase the lateral force coefficient of the truck.(2)The rear drag reducing device has better aerodynamic drag reducing effect in the environment of with/without crosswind,this is because the rear drag reduction device can improve the air flow at the rear of the truck,and it can also reduce the lateral force suffered by the truck,so as to increase the driving stability and safety of the truck in the crosswind environment.(3)Under crosswind condition,the drag reduction effect of non-smooth surface structure is limited,and it will increase the lateral force on the truck.(4)The composite drag reduction device has significant drag reduction effect under all crosswind conditions.When the yaw angle is 12°,the composite drag reduction device has the best drag reduction effect and the drag reduction rate is 68.8%.When the yaw angle is between 0°and 30°,the average drag reduction rate of the composite drag reduction device reaches 37.3%.(5)Under crosswind condition,the compound drag reducing device will increase the lateral force on the truck,and the lateral force coefficient will increase sharply with the greater yaw angle.