Sang-Joon Lee*, Young-Gil Jang and Yong-Seok Choi
The Journal of Mechanical Science and Technology, vol. 26, no. 9, pp.2765-2771, 2012

Abstract : Three-dimensional (3D) flow structures of a turbulent jet issuing from a sharp-edged circular nozzle having multiple triangular tabs are experimentally studied by employing a stereoscopic-PIV (SPIV) system. Two different sharp-edged jet nozzles having 4 and 8 tabs are investigated at a jet Reynolds number of Re = 10,000. The SPIV measurements are carried out at 5 different cross-sectional planes along the jet direction. Spatial distributions of turbulent statistics including mean velocity, mean vorticity, and turbulent kinetic energy are obtained at each cross-sectional plane. The jet entrainment rate showing the mixing of the jet and ambient fluids is also estimated using the measured 3D velocity field information. As a result, the jet issuing from the nozzle with 4 tabs shows better turbulent mixing effect at further downstream position than the 8 tabs case because of the reduced reciprocal interactions of the streamwise vortices that promote the turbulent dissipation.

Keyword : Flow control; Jet; Stereoscopic PIV; Tab; Turbulent mixing