Gas flow measurements by 3D Particle Tracking Velocimetry using coloured tracer particles

This work describes an original approach for 3D Particle Tracking Velocimetry (3D PTV), applicable also for gaseous flows and based on tracer particles of different colours. On the images acquired by several cameras, tracer particles are handled by colour recognition and 3D localisation. Then, the PTV tracking algorithm rebuilds the trajectories of the tracer particles using a criterion of Minimum Acceleration. Theoretical and numerical calculations are first presented to demonstrate that the employed coloured tracer particles follow in a suitable manner the considered gas flows. The test cases analysed comprise low Reynolds number flows involving a variety of interesting features, in particular boundary layer separation, continuous acceleration and recirculations. The experimental setup and the 3D PTV procedure are then described. All results are analysed in a quantitative manner and demonstrate the performance of the developed measurement strategy in gas flows