Interference effects of cooling airflows on a generic car body

In this study, numerical and experimental investigations were performed to understand the effects of cooling-air flow on the vehicle's aerodynamics. A generic car-model was equipped with a simplified underhood section. The cooling air mass flow could be varied to understand the cooling air mass flow on the cooling drag. A variety of measurements and numerical simulations were performed to explain the phenomenona of cooling air flows. Total pressure and hot-wire measurements in the wake of the car visualise the flow field, which is altered by the cooling air. Force measurements, surface pressure measurements and oil-streak patterns were performed to understand the influence of the cooling air on the bluff body. With the measurements and with the CFD-simulations, this study will explain where the cooling drag originates from and how the cooling air interferes with the external aerodynamics.