Analysis of the Base Wake on Passenger Vehicles

Car manufacturers are presented by a continuous increase in fuel prices and by ever more strict legislations regarding CO2-emissions. Decreasing the driving resistance and hence the fuel consumption of their vehicles helps to improve their market share. Aerodynamics plays an important role since it is a significant contributor to the driving resistance at typical driving speeds of 70 km/h and above. Passenger vehicles are defined as bluff bodies of which the main source of air resistance is pressure drag. This drag is caused by the wake a car creates and can be explained by the pressure difference between the front and the rear of the vehicle. Therefore, understanding the behaviour of the wake in time and in space is crucial in order to accomplish the goal of drag reduction. Experimental and numerical investigations have been conducted on a 2WD and 4WD Volvo XC60 to study the effects of geometrical changes to the base pressure and wake shape of the car. Surface pressure measurement equipment and tw