Surrogate model for aerodynamic shape optimization of a tractor-trailer in crosswinds

Abstract

A surrogate model-based aerodynamic shape optimization method applied to the wind deflector of a tractor-trailer is presented in this paper. The aerodynamic drag coefficient of the tractor-trailer with and without the wind deflector subjected to crosswinds is analyzed. The numerical results show that the wind deflector can decrease drag coefficient. Four parameters are used to describe the wind deflector geometry: width, length, height, and angle. A 30-level design of experiments study using the optimal Latin hypercube method was conducted to analyze the sensitivity of the design variables and build a database to set up the surrogate model. The surrogate model was constructed based on the Kriging interpolation technique. The fitting precision of the surrogate model was examined using computational fluid dynamics and certified using a surrogate model simulation. Finally, a multi-island genetic algorithm was used to optimize the shape of the wind deflector based on the surrogate model. The tolerance between the results of the computational fluid dynamics simulation and the surrogate model was only 0.92% when using the optimal design variables, and the aerodynamic drag coefficient decreased by 4.65% compared to the drag coefficient of the tractor-trailer installed with the original wind deflector. The effect of the optimal shape of the wind deflector was validated by computational fluid dynamics and wind tunnel experiment.

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“…Using the sequential quadratic programming (SQP) method, the drag coefficient of the optimal design was reduced by 3.08% compared to the reference design and the relative error is only 0.84% compared to a CFD validation. Gong and Gu combined the kriging model and a multi-island genetic algorithm to optimize the shape of the wind deflector of a tractor-trailer [ 22 ]. Their results showed that the optimized shape of the wind deflector can decrease the drag of the tractor-trailer by 4.65%, compared to the original design.…”