Experimental Investigation of Automotive Vehicle Transient Aerodynamics with a Reduced-Scale Moving-Model Crosswind Facility 2020-01-0671
Automotive vehicles operate in complex, transient aerodynamic conditions that can potentially influence operational efficiency, performance and safety. A moving-model facility combined with a wind-tunnel is an experimental methodology that can be utilized to model some of these transient aerodynamic conditions. This methodology is an alternative to wind-tunnel experiments with actively yawing models or active flaps, and has the added benefit of modelling the correct relative motion between the vehicle and the ground/infrastructure.
Experiments were performed at the moving-model facility at DLR, Göttingen. A 1:10 scale VW Golf 7 (geometry provided by VW) model was equipped with 24 surface pressure taps. The model was accelerated by a hydro-pneumatic driven catapult over a 60 m long track, through a 25 m long test-section, and decelerated in a braking tank of polystyrene balls. Crosswinds were generated by a closed-loop, open-jet wind-tunnel with four 30 kW fans perpendicular to the track, 5 m long and 1 m high, with a maximum velocity of 25 m/s.
The moving-model facility was adapted from its standard high-speed train configuration to a new automotive vehicle configuration. The model was mounted above an existing rolling spine by three cylindrical stings that passed through a slot in a false floor in the crosswind section. The model’s rubber tires made contact with the floor and rotated during the test. Relative yaw angles over the range of 0 - 30 degrees at model velocities of 32-45 m/s (Re = 3.5-5.5x10^6) were tested.
Functionality of the new configuration and on-board data acquisition was achieved. The time-resolved (3 kHz sampling rate) pressure over the surface of the vehicle clearly displays transient characteristics when exposed to crosswind.
This work is part of a collaborative project between the German Aerospace Center (DLR) and the IVK - University of Stuttgart supported by Working Group 6 of the Research Association of Automotive Technology (FAT).
James R. Bell, Henning Wilhelmi, Daniela Heine, Christoph Jessing, Andreas Wagner, Jochen Wiedemann, Klaus Ehrenfried, Claus Wagner
German Aerospace Center (DLR), IVK - University of Stuttgart, FKFS