摘要
As the transport sector is responsible for the consumption of a vast proportion of the oil produced,it is mandatory to research feasible solutions to tackle this issue.The appli-cation of aerodynamic attachments for passiveflow control and reducing resisting aerodynamic forces such as drag and lift is one of the most practicable ways to minimize vehicle energy con-sumption.Theflaps are one of the most innovative aerodynamic attachments that can enhance theflow motion in the boundary layer at the trailing edge of the wings.In the present paper,theflap is designed and modeled for controlling the airflow at the roof-end of a 2D Ahmed body model,inspired by the schematic of theflap at the trailing edge of the wing.As a result,theflap’s geometry and position from the roof-end of the car model are parameterized,which leads to having four design variables.The objective functions of the present study are the vehicle’s drag coefficient and lift coefficient.25 Design of Experiment(DOE)points are considered enabling the Box-Behnken method.Then,each DOE point is modeled in the computational domain,and theflow-field around the model is simulated using Ansys Fluent software.The results obtained for the DOE points are employed by different regressors,and the relation between design variables and objective functions is extracted using GMDH-ANN.The GMDH-ANN is then coupled with three types of optimization algorithms,among which the Genetic algorithm proves to have the most ideal coupling process for optimization.Finally,af-ter analyzing the variations in the geometry and position of the roofflap from the car roof-end,the roof-flap with specifications of L=0.1726 m,a=5.0875°,H=0.0188 m,and d=0.241 m can optimize the car drag and lift coefficients by 21.27% and 19.91%,respec-tively.The present research discusses the opportunities and challenges of optimal design roof-flap geometry and its influence on car aerodynamic performance.
