Experimental study of Counter-Rotating Vortex Pair Trajectories induced by a Round Jet in Cross-Flow at Low Velocity Ratios

摘要

Circular flush Jets In Cross-Flow were experimentally studied in a watertunnel using Volumetric Particle Tracking Velocimetry, for a range of jet tocross-flow velocity ratios, r, from 0.5 to 3, jet exit diameters $d$ from 0.8cm to 1 cm and cross-flow boundary layer thickness delta from 1 to 2.5 cm. Theanalysis of the 3D mean velocity fields allows for the definition, computationand study of Counter-rotating Vortex Pair trajectories. The influences of r, dand delta were investigated. A new scaling based on momentum ratio r_m takinginto account jet and cross-flow momentum distributions is introduced based onthe analysis of jet trajectories published in the literature. Using a rigorousscaling quality factor Q to quantify how well a given scaling successfullycollapses trajectories, we show that the proposed scaling also improves thecollapse of CVP trajectories, leading to a final scaling law for thesetrajectories.