Aerodynamic Shape Optimization of a Container-Truck's Wind Deflector Using Approximate Model 2010-01-2035

Due to the energy crisis, one of the important challenges in the Auto industry is to reduce the fuel consumption of the vehicle. And the higher speed is, the more fuel consumption is taken by the aerodynamic drag. Mostly, the aerodynamic drag lies on the shape of the vehicle. Consequently, the improvement of the aerodynamics of vehicle shape, more precisely the reduction of their aerodynamic drag, becomes one of the main topics of the automotive researchers.

For a container-truck, the three dimensions of the container are standard and unchanged, and the shape of cab is almost fixed by the aesthetic sculpt. For those container-trucks, aerodynamic additional equipments can decrease the aerodynamic drag evidently, especially the wind deflector. Accordingly, this paper describes a method which combines CAD, CFD, Approximate model and optimization carried out on the aerodynamic shape of a container-truck's wind deflector. The main objective of this study is to minimize the drag coefficient of the container-truck running in the speed of 30m/s.

The Design Variables used for the research are height, length, radius and stretch for characterizing the shape of the wind deflector. To explore the design space and identify significant design variables, a 20-level DOE study was carried out using Design of Experiments. A Kriging model based on DOE database is created. For examining and certifying the fitting precision of the Kriging Model, another three design points which besides the 20 DOE design points are chosen to analyse the tolerance of results between the Kriging Model and the real simulations. Finally the Kriging Model is subsequently used for executing the optimization of aerodynamic shape by Multi-island Genetic Algorithm. To a large extent, it saves time compared to the real simulations. Compared to a container-truck without a wind deflector, the optimum design obtained is 9.73% decreased.