Application of Particle Image Displacement Velocimetry (PIDV) to Complex Flows: Velocity Field Measurements in Front of a Heavy Gas Cloud

摘要

The applicability of the particle image displacement velocity (PIDV) technique to the velocity field in front of clouds of heavy gases during instantaneous releases, to improve the understanding and modeling of air entrainment phenomena, was assessed. Time dependent features of the system and the implementation of a mirror to resolve the low velocity area and the direction ambiguity are described. The mixing areas in front are shown by determining the vorticity field. The motion of the air induced by the heavy gas flow is also considered. The velocity field during the impact of the front on a vertical wall is measured. Results demonstrate the applicability of PIDV to measurements in time-dependent conditions, and the possibility of this technique to determine the direction of the velocity vectors, thus resolving all the velocity range when an artificial velocity is superimposed using a mirror. The high resolution in measurements allows the determination of the vorticity field, and could also allow the local verification of the continuity equation if the concentration map, i.e., the local density was measured.