Aerodynamic Features Optimization of Front Wheels Surroundings for Energy Efficient Car

Constant development of the vehicles energy efficiency, the fuel prices and the requirements for greenhouse gas emissions force designers to find new solutions to achieve the goals by minimising the movement resistances. As it was calculated basing on the research carried out at the Silesian University of Technology, the Institute of Fundamentals of Machinery Design on energy efficient cars designed for the Shell Eco-marathon race, the main component of the total resistance of a moving car is the aerodynamic drag which is equal, in such a type of car, to about 70% of the total movement resistance. The idea of the research is to optimize the shape of aerodynamic features of the front wheels surroundings. By the front wheel surroundings aerodynamic features, the front wheel arch and front bumper shapes are understood. The air drag depends on the elements of the drag coefficient cxwhich is strongly connected with its shape and its area. Front wheel in motion rotates and generates air turbulences which have negative influence on the car aerodynamics. In majority of the cars the front wheels are swivel, which makes it difficult or impossible to close the front wheel arch. For reduction of the air drag generated by the open wheel arch, three types of solutions are designed and optimized. The first solution is the main shape of the analysed car parts which are shaped so that they generate minimal aerodynamic drag and lead the air stream to bypass the wheel niche. The second analysed solution is passive system consisting of respectively shaped holes in the front bumper. The holes lead the air stream into the wheel niche, equalize pressure in the wheel niche and reduce the air turbulences generated by the rotating wheel. The last solution is a set of overlays which lead the air stream in such a way to avoid its disruption to the wheel arch niche and achieve the best air stream distribution around the vehicle.