An Applied Study on the Influence of the Vehicle Body Shape on Air Resistance

摘要

The current high-geared developments within the automotive sector have triggered a series of performance, comfort, safety and design-related issues. Hence, oftentimes manufacturers are challenged to combine various elements so as to achieve an attractive design, without diminishing the vehicle's dynamic performance. Under the circumstances, the shape of the vehicle body becomes the key element that connects the design component with the performance requirement, since it directly influences the value of the resistance forces, and, respectively the air resistance. Aerodynamics is the branch of mechanical engineering that deals with the movement of gases (especially the air) and their effects on fluids. As far as the automotive sector is concerned, aerodynamics focuses mainly on the flow of the air currents over the vehicle body. When designing vehicle, the positive or negative displacement of the airflow is studied in aerodynamic tunnels. It is preferable for the negative displacement to push the vehicle as close to the ground as possible. In what follows we set out to study the influence of the drag coefficient and, implicitly, of the air resistance on vehicle performance. Hence, we will carry out comparative analysis of two vehicles with similar technical characteristics, but with different bodies, i.e. a hatchback and a sedan. The results obtained are then compared both by means of the analytical determination of the air resistance and via a simulation performed within the Virtual Crash software platform. The results recorded show that of the two vehicles, with the considered aerodynamic coefficients, hatchback type vehicle displays lower values in terms of air resistance.