Research On Aerodynamic Characteristics Of Heavy-duty Truck Travelling Under Cross-wind

It is very often that encounter cross-wind, when a vehicle is travelling on road.While a vehicle travels at low speed, the influence of low speed cross-wind isnegligible, But it is totally different while the speed of both are very high, and thedriving stability would suffer strong interference of the cross-wind. Vehicle trafficsafety would be greatly reduced. Especially for heavy-duty truck that has high lateralwall, the entire lateral side of lorry would be exposed to cross-wind, and that wouldseriously affect driving stability of the truck, even roll-over risk exists.Heavy-duty trucks are usually used to do long-haul trucking word, and they oftentravel on expressways, that are very likely to expose to cross-wind. Usuallyexpressway is significantly higher than the ground around, and this contract will leadto increase the speed of cross-wind. When a bridge exists on the expressway, the flowfield around the truck would be more complex, and the aerodynamic loads would bedifferent as usual, also the heavy-duty truck traffic safety would be impact.In this paper, there are two parts of studies. One is research on the influence ofthe shape of truck nose on cross-wind aerodynamic characteristics of heavy-dutytruck, and the other is research on changes of aerodynamic characteristics when aflat-head heavy-duty truck very usual in china travels across Expressway Bridgeunder crosswind.In the first part, stable numerical simulation using ANSYS FLUENT is used todo research on the influence of truck nose on cross-wind aerodynamic characteristicsof heavy-duty truck. FLUENT is one of most popular commercial CFD software inthe world, and it has advantages in solution stability and calculation accuracy.Numerical simulation studies using FLUENT have been very mature. In this part ofstudy, the prototype of the heavy-duty truck is a flat-head heavy-duty truck, and theshort nose truck and the long nose truck are modeled by lengthening the shape of the nose of flat-head truck. Through numerical simulation, the changes of aerodynamicloads on heavy-duty trucks with different nose shapes under crosswind are got, aswell as different flow structures around the bodies of the three heavy-duty trucks.In the second part, transient numerical simulation using OVERSET MESHtechnology of SC-Tetra software from Japan Cradle CORP is adopted to performsimulation of heavy-duty truck moving across an expressway bridge under cross-wind.In this paper, a standard expressway bridge with guardrail is modeled, and the valuesand variations of aerodynamic loads while a heavy-duty truck moving across thebridge are gotten through transient numerical simulation, and the flow fields aroundthe truck in different position are also studied.This paper can provide some guidance for heavy-duty trucks nose styling, andthe aerodynamic loads data obtained through transient numerical simulation of theprocess of heavy-duty truck moving across expressway bridge under cross-wind canbe used as the initial signal to do further research on autopilot and system dynamicsfor truck study.