基于气动减阻和散热需求的主动格栅优化设计

Active Grille Shutter Optimal Design Based on Aerodynamic Drag Reduction and Heat Dissipation Requirements

摘要:

主动进气格栅可通过控制车辆前端进气开口面积提升燃油经济性。不同车辆行驶工况下的格栅转角和风扇转速控制是主动格栅研究中的一大难点。首先结合风洞试验与数值仿真验证了计算流体力学模拟与发动机冷却系统一维模型的精度，其次通过最优拉丁超立方抽样和神经网络拟合方法构建了主动格栅转角、冷却风扇转速、车速与阻力系数、冷却风速间的近似模型，将其输入至冷却系统模型中，根据实时的发动机冷却需求提供空气流量，并选择阻力系数最小的转角组合进行控制，最终可实现在不同环境温度下使循环工况燃油降比在0.6%~0.7%。

关键词:主动格栅;气动阻力;冷却性能;近似模型;联合仿真

Abstract:

Active grille shutter can control vehicle front-end opening area, thereby the fuel economy will be improved. The control of grille angle and fan speed under different vehicle driving conditions is a difficulty in the research of active grille shutter. Firstly, the accuracy of both computational fluid dynamics simulation and engine cooling system one-dimensional model were verified by wind tunnel tests and numerical simulation separately. Secondly, an approximate model considering the AGS angle, cooling fan speed, vehicle speed and drag coefficient, cooling air velocity was constructed by optimal Latin hypercube sampling and neural network fitting method, and then the model was input to the cooling system model. According to the real-time engine cooling demand, the AGS angle which can both meet the cooling requirements and minimum drag coefficient was chosen out. Finally the fuel reduction ratio of 0.6%~0.7% could be achieved under different ambient temperatures.

Key words:active grille shutter;aerodynamic drag;cooling performance;approximate model;co-simulation