On-road determination of aerodynamic drag improvements

Abstract

The objective of this work is an attempt to understand the potential for aerodynamic improvements by the application of di erent under oor panels that might be masked by traditional xed-ground wind tunnel testing. The coastdown method is chosen to determine drag coe cients on the road which could then be compared with wind tunnel data. Of prime importance were the simplicity and practicability of the developed analysis method, with particular emphasis on industrial applicability. As a result of the investigations, the resolution of the new method and an astonishing conformity of the identi cation of small changes in the under oor con guration of the test vehicle with wind tunnel tests are demonstrated. Keywords: vehicle aerodynamic improvements, under oor panels, on-road method NOTATION A vehicle frontal area (m2) c d air drag coe cient c i drag coe cients (N s/m, N s2/m2) F rm rolling and mechanical losses (N ) m vehicle mass (kg) m d vehicle e ective mass (kg) t time (s) ¢t duration of coastdown (s) v vehicle speed (m/s) v max maximum vehicle velocity (m/s) v min minimum vehicle velocity (m/s) v r total relative airspeed (m/s) r air density ( kg/m3)

Facilitating Engineering Mathematics Education By Multidisciplinary Projects

“…Students are highly motivated by tasks that stem from real engineering problems arising from their field of study. The second example specified below resulted from a conjoint research project with BMW 4 . The objective of this work was the investigation of aerodynamic improvements by the application of underfloor panels.…”