The Aerodynamics of Cooling Air Inlets of Road Vehicles

Paper in proceeding, 2009

To reduce carbon dioxide (CO2) emissions of road going vehicles, the aerodynamic drag is an important area to focus on. Reducing aerodynamic drag will lead to reduced fuel consumption and hence decreased CO2 emissions. A significant element of the aerodynamic drag of a modern passenger car is the cooling drag, which can constitute up to 15%. Possible solutions to reduce the cooling drag include closing off parts of the cooling air inlets when only a small amount of cooling air flow is needed. The focus of this study is on the aerodynamic effects closing off the cooling air inlets have on a modern passenger car. Both full size and scale model experiments were utilized, together with computational fluid dynamic (CFD) simulations. Results show that reduction in aerodynamic drag is possible by closing off the lower cooling air inlet and furthermore that this has a noticeable effect on the base pressure. The effect on the base pressure was, however, found to be a little less significant as that caused by completely closing the cooling air inlets.