Vortex structure and heat transfer in the stagnation region of an impinging plane jet (simultaneous measurements of velocity and temperature fields by digital particle image velocimetry and laser-induced fluorescence)

Velocity and temperature in the stagnation region of an impinging plane jet were simultaneously measured by digital particle image velocimetry and laser-induced fluorescence. Counter-relating vortex pairs observed in the stagnation region sweep cold fluid toward the wall and eject high-temperature fluid toward the outer region. The weighted PDF of the turbulent heat flux indicates that the contribution of this ejection mechanism to the net heat flux is dominant. The streamwise vortex pair is transported from the free-jet region to the stagnation region and the vorticity is amplified by the main stream of what in the vicinity of the wall. (C) 1997 Elsevier Science Ltd.