Investigation of three dimensionality in the near field of a round jet using stereo PIV

Abstract

A round air jet at a Reynolds number of 19 000 was studied using stereo PIV techniques in an effort to understand the characteristics of all three velocity components in the developing shear layer and to study the evolution of three dimensionality with increasing axial distance. Pulsed laser sheets were aligned to illuminate the centreline plane of the jet. The stereo PIV set-up was suitably calibrated to translate the resulting pixel displacements into axial, radial, and azimuthal velocity components. Details of measurement accuracy are discussed and related to the presence of local velocity gradients. Experimental results show that the RMS of the azimuthal velocity is of the order of 0.1V0..