Abstract
In terms of fuel consumption, the car performance can be understood as one of the qualities attained by a vehicle: extending the maximum distance driven, increasing the maximum travel velocity, decreasing fuel consumption and reducing the greenhouse gas emissions, all on an equal amount of gasoline as compared to the baseline performance measure. One of the ways to achieve the above can be through a reduction of an automobile drag. Reducing aerodynamic drag, in turn, means a reduction of a drag coefficient parameter (cx). This must be preceded by a thorough understanding of physical phenomena of air flow around the vehicle, including upper volume, underbody, accessories, vehicle's aerodynamic circuits (powertrain, brakes, ventilation), and wheels. In the presented study the investigation of the aerodynamic influence of the rotating wheels on the carbody has been considered as an important aspect of lowering vehicle’s aerodynamic drag. A simplified one quarter model of a real car (scale 1:1) (see Fig.1) was used for the Particle Image Velocimetry (PIV)-based wind tunnel tests performed by PSA Peugeot Citroen in Magny Cours, France, in order to investigate the role of wheels in overall vehicle drag. Alongside, CFD simulations of air flow using ANSYS CFX software were conducted to enable formulation of wider conclusions on how the shape of tires influences the car drag.
KEYWORDS – wheel aerodynamics, Particle Image Velocimetry (PIV), CFD, wind tunnel, flow visualization