On-Road Measurements of Aerodynamic Lift Compared with Wind Tunnel Data 960900
The principal development tool for the vehicle aerodynamicist continues be the full-scale wind tunnel In the absence of a reliable alternative it is expected that this will continue for many years
As a true simulation of conditions on the road, the conventional full-scale wind tunnel has limitations In most cases the ground is fixed relative to the vehicle allowing an unrepresentative boundary layer to develop, the wheels of the test vehicle do not rotate and there is some uncertainty over the influences imposed by the tunnel walls These factors are known to influence measured aerodynamic data.
This paper describes a technique for the measurement of aerodynamic lift on the road Results for a medium-sized European passenger car are compared with measurements made in a traditional full-scale fixed ground wind tunnel While there was found to be reasonable agreement between the road and wind tunnel values of total lift, the distribution of lift between front and rear axles was noticeably different On the track more front lift and less rear lift were measured compared to the wind tunnel
The technique for measuring lift on the road was originally developed to help substantiate assumptions made in the comparison of track and wind tunnel derived aerodynamic drag data - the subject of a previously published paper
In their own right the results published in this paper contribute to the continuing investigation of the simulation problem within the automotive aerodynamics community particularly as there is little published data of road derived lift measurements for passenger cars