In an environment of tougher engineering constraints to deliver tomorrow's aerodynamic vehicles, evaluation of aerodynamics early in the design process using digital prototypes and simulation tools has become more crucial for meeting cost and performance targets. Engineering needs have increased the demands on simulation software to provide robust solutions under a range of operating conditions and with detailed geometry representation. In this paper the application of simulation tools to wheel design in on-road operating conditions is explored.
Typically, wheel and wheel cover design is investigated using physical tests very late in the development process, and requires costly testing of many sets of wheels in an on-road testing environment (either coast-down testing or a moving-ground wind-tunnel). This paper is a follow-up to a study by the same authors, in which the aerodynamic drag performance of wheel designs was evaluated in a static ground wind-tunnel and simulation environment. In the present study, new experimental data using on-road coast-down tests is shown to verify the drag benefits of key wheel and wheel cover designs. The data is compared to a simulation study with commercial CFD software using an on-road configuration with moving ground and rotating tires. The simulation data is well-correlated to the experiment, and through analysis of the flow data, it provides insight into the mechanism of drag reduction. The study is successful in establishing simulation as a reliable means to evaluate wheel designs and the potential for drag savings early in the vehicle development process, with much less cost than physical tests.