Flow field analysis of a turbulent slot air jet impinging on a moving flat surface

摘要

The flow field topology of a confined turbulent slot air jet impinging normally on a moving flat surface has been investigated experimentally by using particle image velocimetry (PIV). Experiments were conducted for a nozzle-to-plate spacing of eight slot nozzle widths, at three Reynolds numbers (Re = 5300, 8000 and 10,600) and four surface-to-jet velocity ratios i.e. 0, 0.25, 0.5 and 1. The measurements of the mean velocities and turbulent quantities are presented in the following main characteristic regions of the jet: the potential core, the intermediate zone and the impinging zone. It appears that the flow field patterns at a given surface-to-jet velocity ratio are independent of the jet Reynolds number in the range of 5300-10,600. A slight modification of the flow field is observed for a surface-to-jet velocity ratio of 0.25 whereas at higher ratios of 0.5 and 1, the flow field is significantly affected.