Aerodynamic Interaction Effects and Surface Pressure Distribution during On-Road Driving Events

Temporal changes of the onset flow field during on-road driving events, such as overtaking and passing, causes a complex interaction between aerodynamics of two vehicles. This can affect vehicle dynamics as well as steering input from the driver. In extreme situations this can cause a risk to driving comfort and safety. In order to optimize the shape of a vehicle, a fundamental understanding of the underlying pressure distribution during these scenarios is necessary. This paper describes the experimental method to measure the surface pressure and vehicle motion during overtaking a vehicle and passing a vehicle on a proving ground. Two primary vehicles, a C-Hatchback and a B-Crossover, were instrumented and a medium sized van and a 3.5 t truck were used as secondary vehicles without instrumentation. The highly asymmetric pressure distribution acting on the primary vehicles during the driving events is characterized using a simplified illustration method. The pressure experienced by the test vehicles were qualitatively the same, but were more severe when passed or overtaken by vehicles with a larger displacement area and corresponding vehicle front end pressure field.