Multi-angular recording technique on a single camera for 3D measurements in fluid mechanics

Abstract

The three-dimensional measurement approaches are used more and more frequently in fluid mechanics, whether to measure flow velocity, to detect of surface location (vibration, liquid gas interface) or to obtain a scalar field (flame emission, LIF 3D, density.. .). In practice, they consist mainly in observing the area of interest from different angles of view before carrying out a volume reconstruction, the number of viewing angles often having to be greater than three. These 3D approches lead to a significant complexity in the optical arrangement and induces significant costs (cameras, lenses ...). For surface reconstruction, it is possible in some cases to consider approaches where several angles of view are recorded on the same detector. In this work, this kind of approach is considered by using an optical device placed in front of a single camera to record four angles of observation on the same sensor. For surface localisation, using the technique of speckles, this recording approach is validated from four different examples. The accuracy of surface localisation is assessed and potentials of our approach for investigating fluid/structure interactions are demonstrated.