On the flow characteristics of normal and inclined square jets in cross-flow: a numerical study

Numerical simulation has been performed by solving full Navier–Stokes equations governing the three-dimensional unsteady compressible flows. The main goal of the present work is to investigate the flow characteristics of a square jet issuing transversally into a cross-flow at three injection angles of 90°, 60° and 30°, and thus to provide some deeper insights into the physical flow mechanism governing the normal and inclined jets in cross-flow. The simulation uses the jet to cross-flow velocity ratio of 2.5 and the Reynolds number based on the free-stream quantities and the jet exit diameter is 225. While the vortical structures predicted from the normally jet were in good qualitatively agreement with the findings of other researchers, our simulations have shown that both the jet penetration and jet cross-flow mixing are strongly dependent on the jet inclination angle. As expected, the jet spreading angle and penetration depth are observed to be greatest from the normal jet case. It has also found from the simulations that the streamwise jet inclination weakens significantly the cross-flow entrainment into the near wake region. These observations and information are of great practical relevance notably for cooling system of turbine blades designer. Key-Words: Direct numerical simulation, Jets in cross-flow, Vortex structures, Jet penetration and spreading, Cross-flow entrainment.