Characterization of the Transient Airflow Around a Vehicle on Public Highways

Abstract

Natural wind, roadside obstacles, terrain roughness, and traffic can influence the incident flow of a vehicle driven on public roads. These on-road conditions differ from the idealized statistical steady-state flow environment utilized in CFD simulations and wind tunnel experiments. For this reason, the transient aerodynamic characterization of the airflow around a vehicle used under such conditions is shown in this paper. A compact car was equipped with a measurement system that is capable of determine the transientairflow around the vehicle and the vehicle’s actual driving state. A fixed driving route on public highways in southern Germany was driven several times, with that vehicle. The tests were conducted under consistent weather conditions and average wind velocities of 2-5 m/s. During the tests the transient incident flow and pressure distribution on the vehicle surface were measured and considered in this paper. Additionally, theground clearance occurring during the tests is discussed. The results of this paper contribute the characterization of the aerodynamic real-world driving conditions on public highways. Furthermore, the results aim to provide a reference case for the integrationof the real-world on-road driving conditions into CFD simulations and wind tunnel experiments.