Dual-plane Stereoscopic PIV Measurement on the Lobed Jet Mixing Flow

In a continuing effect to study the mixmg enhancement by large-scale streamwise vortices in lobed mixing flows, an advanced PIV system named as dual-plane stereoscopic PIV system was used in the present study to conduct simultaneous vorticity (all three components) measurement of an air jet exhausted from a lobed nozzle. Unlike 'classical' 2-D PIV system or conventional 'single-plane' stereoscopic PIV system, the dual-plane stereoscopic PIV system used in the present study can obtain the flow velocity (all three components) fields at two spatially separated planes simultaneously. Therefore, it can provide the distributions of all the three components of vorticity vectors instantaneously and simultaneously. The evolution and interaction characteristics of the large-scale streamwise vortices and azimuthal Kelvin-Helmholtz vortices in the lobed jet mixing flow were revealed instantaneously and quantitatively from the measurement results of the dual-plane stereoscopic PIV system. The characteristics of the mixing process in the lobed jet mixing flow were analyzed based on the simultaneous measurement results of the steamwise vorticity and azimuthal Kelvin-Helmholtz vorticity distributions.