Investigation of Axisymmetric Free Air Jet at Moderate Reynolds Number Using DPIV

Abstract

Using DPIV measurement method, 2-D instantaneous velocity distributions in both near and far fields of a axisymmetric free air jet at moderate Reynolds numbers are measured in detail. The vorticity distributions and stream line maps also are calculated from these measured velocity distributions. By ensenblely averaging instantaneous velocity distributions, some statistical parameters of jet, i.e., mean velocity, mean turbulent intensity, are calculated. The statistical characteristics of jet are analyzed in detail. These measurement results of statistical characteristics confirm with that obtained by previous researchers by pointless methods. According to the measurement results of instantaneous velocity and vorticity distributions as well as that of flow visualization, the evolution process of vortex in shear layer are also analyzed, such as, originating, growing, pairing, deforming, and breaking down