New Particle Tracking Velocimetry

Particle Image Velocimetry (PIV) is a non-intrusive optical measurement method to capture flow velocity fields. It provides the simultaneous visualisation of the two-dimensional streamline pattern in unsteady flows and the quantification of the velocity field over a plane. To reveal the flow motion, the flow is seeded by small scattering particles. The instantaneous fluid velocities are evaluated by recording the images of tracers, suspended in the fluid and traversing a light sheet. A PIV system consists of seeding particles, illumination unit, image acquisition system, and a processing computer with appropriate software. For industrial applications a standard PIV system is not suitable, for its costs, sizes and needs of specialised users and work areas. In this paper, the realisation of a new PIV system is described and compared with the standard PIV. The solution proposed is a Continuous PIV, CPIV, system: with respect to a standard PIV, it is composed of a continuous laser light source, a low cost standard CCD camera. A specifically new image-processing algorithm has been developed. This studies the grey level distribution in the particle trace image, and indicates those particles moving with an out-of-plane velocity vector component and the measure with a limited error.