Influence of Unsteady Aerodynamics on Driving Dynamics of Passenger Cars
Huemer, J.; Stickel, T.; Sagan, E.; Schwarz, M.; Wall, W.A.
Ingenieurwissenschaften | chassis development; cross-wind; driver perception; straight line behaviour; unsteady aerodynamics; vehicle stability
Recent approaches towards numerical investigations with CFD-Methods on unsteady aerodynamic loads of passenger cars identified major differences compared to steady state aerodynamic excitations. Furthermore innovative vehicle concepts like electric-vehicles or hybrid drives further challenge the basic layout of passenger cars. Therefore the relevance of unsteady aerodynamic loads on cross-wind stability of changing basic vehicle architectures should be analysed. In order to assure and improve handling and ride characteristics at high velocity of the actual range of vehicle layouts the influence of unsteady excitations on the vehicle response was investigated. For this purpose a simulation of the vehicle dynamics through multi-body simulation was used. The impact of certain unsteady aerodynamic load characteristics on the vehicle response was quantified and key factors were identified. Through a series of driving simulator tests the identified differences in the vehicle response were evaluated regarding their significance on the subjective driver perception of cross-wind stability. Relevant criteria for the subjective driver assessment of the vehicle response were identified. As a consequence a design method for the basic layout of passenger cars and chassis towards unsteady state aerodynamic excitations was defined.