Recent advancements towards large-scale flow diagnostics by robotic PIV

The present work reviews the recent developments in the domain of particle image velocimetry (PIV) with attention to its use for large-scale problems of interest for industrial aerodynamics. The article introduces the fundamental principles of flow seeding for large-scale experiments based on the helium-filled soap bubble (HFSB) technique. The measurement of flow tracers in a three-dimensional domain is presented, which is based on Lagrangian tracking methods. Furthermore, the concept of co-axial volumetric velocimetry is introduced and its combination with robotic arm manipulation is shown. The work presents two main examples of applications to aerodynamic problems: The first is the flow field around a propeller aircraft at wind tunnel free-stream velocity up to 50 m s-1, which to date is considered the boundary of large-scale PIV application with HFSB. The second example is the complex three-dimensional flow field around a cyclist at full scale. The work summarizes developments obtained in the last 3 years of research, demonstrating that the domain of PIV techniques is still undergoing vivid developments.