On-road Ring-of-Fire measurements of following SUVs at moderate distances

In this study, a proof-of-concept application of Shake-the Box measurements employing the 'Ring-of-Fire' technique was performed to capture the full wake of a sport utility vehicle (SUV) in a single driving and a following configuration, travelling at a speed of 13.89 m/s (50 km/h). The study also introduces novel processing techniques of such measurements, including the lateral alignment of the multiple measurement runs directly within the 3D Calibration. A hybrid hardware approach was utilized, combining low-speed PIV cameras with a high-speed illumination system, with the aim of improving the practicability and ease of use of such a system, while ensuring sufficient spatial resolution along the out of plane axis. Eight 25-megapixel (5328 x 4608) cameras were used, operated at a reduced resolution of 2112x 1024 pixels and an acquisition frequency of 150 Hz, covering a cross-sectional field of view of 3.7 m x 1.6 m. Two configurations were compared, where on one, a Subaru Solterra was tested standalone at 13.89 m/s. The second configuration also captured the wake of the Subaru Solterra, but in a configuration where the Solterra was following a Mazda CX-5 with a distance of 20 m at again 13.89 m/s.