Abstract
Effects of vortex generators (VGs) on velocity and scalar diffusion on an axisymmetric jet are experimentally investigated. Instantaneous velocity and temperature are simultaneously measured using a hot wire anemometer and a cold wire thermometer, respectively. The air flow is generated by a wind tunnel, and forms axisymmetric jet from the circular skimmer whose diameter is 30 mm. A heater is placed at the entrance of the wind tunnel to heat the air. Heat is introduced as a passive scalar in this study. 6 VGs are installed circumferentially on the edge of the skimmer with a constant interval. The configurations of the VGs are varied and 11 patterns using up to 4 of them are tested. The results show that the VGs increase fluid entrainment in the upstream region but become ineffective in the downstream region. On the other hand, the VGs promote thermal diffusion and the effect increases with the number of VGs. The present study suggests that it is possible to control jet diffusion by arranging the locations of the VGs.
