Aerodynamic Optimization of Vehicle Configuration Based on Adjoint Method 2020-01-0915
With emission reduction taken as the priority by the whole society, in order to cut down on the fuel consumption for automotive manufacturers, aerodynamics plays a significant role in optimizing the exterior configuration for developing low drag vehicles. Of all the optimization approaches, the gradient-based adjoint method has currently gained much attention for its high efficiency in calculating the observables sensitivity with respect to shape parameter variation, which is the first step for subsequent shape optimization.
In this work, the main goal is to evaluate the adjoint method on optimizing the vehicle shape for a lower drag design based on a production SUV. Firstly, the influence of different mesh schemes were discussed on sensitivity calculation results of aerodynamic drag. According to the sensitivity results, several key areas, like the side mirrors, the rear spoiler, the diffusor and the rim of the wheels, were respectively altered through mesh morphing process. Steady Reynolds Averaged Navier Stokes (RANS) approach was used for the primal flow solution of adjoint calculations, while transient simulation with Stress Blended Eddy Simulation (SBES) was also performed on the baseline and the optimized vehicle for more precise flow solution. The final drag reduction is five count for RANS, and four count for SBES. In addition, the drag reduction result of the optimized vehicle was evaluated and correlated with full-scale wind tunnel test.
This paper validated the effectiveness of adjoint method for aerodynamic optimization of a full-production vehicle, which indicates more extensive application of this approach for the shape design in the early stages of vehicle development.