Investigation of Features of Flow of Three-Dimensional Turbulent Wall Jets with and Without Pressure Gradient

摘要

The characteristics of 3-dimensional wall jets are strongly influenced by secondary motion particularly in the region close to the nozzle. There is evidence suggesting that jets from narrow and tall nozzles will spread a wall jet more broadly over a wall than low and broad nozzles. Three-dimensional wall jets with pressure gradients, in the region close to the nozzle are subject to the same effects of secondary motions as are wall jets without pressure gradients, while in their later course they may acquire the characteristics of turbulent flow in ducts. Theoretical investigation of the action of Reynolds stresses serves to clarify the nature of secondary motions and to show the reason for contrasting characteristics of secondary flow in jets and in ducts as well as the fading out of secondary motion with increasing jet diffusion. (Author)