The flow structure of convex surface target with narrow space under round jet impingement was investigated by smoke wire flow visualization.Reynolds number Re(750-1500)

the ratio of the jet impingement distance to the diameter of the jet hole H/d(0.2-1)

and the relative curvature d/D were modified in this experiment.The changes of flow separation angle and vortex dependently of above-specified parameters were analyzed through capture of flow field state.The results shows that

when Re

H/D are larger

a stable vortex is generated at two sides of the convex surface.With the increase of Re and H/D

the air separation is delayed when the radius angle of jet flow corresponding to surface separation increases.It was also observed in the experiment that the separation was caused in advance and the corresponding radius angle decreased when d/D declined.