桥上轿车并行超车的风致安全评价及横向运动控制

Wind-induced safety evaluation and lateral motion control for car parallel overtaking on bridges

为厘清并行超车过程中“风-车-桥”的气动交互干扰及其对轿车侧风稳定性的影响,采用空气动力学与系统动力学耦合方法建立了侧风环境下桥上轿车分别超轿车和货车的风致安全评价模型,揭示了轿车超车过程中气动侧力和气动横摆力矩的变化规律及作用机理,基于线性二次最优控制的路径跟踪模型分析了轿车超车过程中有、无控制作用时侧偏运动和横摆运动的差异。结果表明,“风-车-桥”气动交互干扰形成的高速低压区和低速低压区对行车安全有显著影响,影响程度与被超车类型及所在车道有关:轿车超轿车时,在迎风侧第1车道超其他车道轿车时为较危险工况;轿车超货车时,在迎风侧第1车道超其他车道货车及在第2车道超第1车道货车时为较危险工况。研究结果可为提升桥梁风致行车安全能力提供参考。

To investigate the aerodynamic interaction between“wind-vehicle-bridge”during the parallel overtaking process and its effects on the car‘s crosswind stability,a combined approach of automotive aerodynamic and system dynamics is proposed.This method is used to carry out a wind-induced safety evaluation for car parallel overtaking on bridges in crosswind environments.First,the transient motion of a car parallel overtaking on a bridge is analyzed using the coupling method of composite wind and moving mesh.This reveals the variations and action mechanism of aerodynamic side force and aerodynamic yaw moment during car parallel overtaking on a bridge.Subsequently,a path-tracking model and linear quadratic optimal control method are used to establish simulation and control systems for car overtaking in crosswinds.Finally,in the absence of lateral motion control,the wind-induced safety capability during a car overtaking a car and a car overtaking a truck is quantitatively evaluated by lateral displacement and yaw angle.Meanwhile,in the presence of lateral motion control,the front wheel angle is considered.The results indicate a noteworthy impact on driving safety resulting from low-pressure regions,which are created by the aerodynamic interaction of“wind-vehicle-bridge”.The low-pressure regions with high velocity are situated on the windward side of the overtaken vehicle,and the low-pressure regions with low speed are situated on the leeward side of the overtaken vehicle.This effect on wind-induced safety depends on the type of overtaken vehicle and its travel lane.Overtaking on the first lane of the windward side is highly dangerous for cars.Additionally,caution must be taken when a car overtakes a truck on the second lane of the windward side while the truck is on the first lane of the windward side.The study‘s research methodology and results can offer a theoretical framework to enhance the wind-induced driving safety capacity of bridges during high winds.