Study Of Aerodynamic Drag Reduction Feature On Automobile With Non-smooth Groove Surface

With the rapid development of road transportation and the popularity of automotive in our country, the number of automotive has maintained a strong growth rate, which is expected to reach270million in2020. In the flourishing process of automobile industry, China also faces enormous energy challenge. Nowadays the oil resources are scarce and the prices are continuingly rising, which make the improvement of aerodynamic feature and fuel economy of automobile become more and more important.Automobile resistance includes rolling friction resistance and aerodynamic resistance. Aerodynamic resistance is the main drag when automobile is running, so the majority of fuel consumption is consumed in overcoming the aerodynamic drag. Generally speaking, the faster an automobile runs, the more fuel is consumed in aerodynamic drag. For high-speed automobile, by reducing the aerodynamic resistance to improve the aerodynamic drag reduction feature, the result shows that the way can save fuel significantly.Base on the research that bionic non-smooth surface has less viscosity reduction and resistance, the paper has V-shaped groove applied for automobile body, which has the best drag reduction effect. The paper uses computational fluid dynamics(CFD) simulation method to study the automobile aerodynamic drag reduction feature. The main contents are listed as follows.Firstly, by researching the automobile external flow field, the paper analyzes the influence of V-shaped groove non-smooth surface that applied on automobile body on the aerodynamic drag, including pressure drag, skin friction drag and induced drag. Secondly, based on the theory of projecting height and second vortexes, the paper analyzes the microscopic drag reduction mechanism of groove, for further verify the validity of groove non-smooth surface that can improve aerodynamic drag reduction feature of automobile. Then, the paper compares automotive resistance coefficient with the condition of different automotive driving speed, angle and height of the groove surface and analyzes the influence these factors exert on the drag reduction effect of automobile, which will provide some guidance for the reasonable selection of groove structure. Finally,the paper also adopt automotive fuel economy as the evaluation standard of the performance of aerodynamic drag reduction. The result shows that a reasonable groove structure and a certain speed range will result in better fuel economy and obtain a better aerodynamic drag reduction performance, which will provide a theoretical basis for real automobile application in the future.