Impingement heat transfer from the rib roughened surface with two-dimensional arrays of circular jet has been investigated in comparison to the jet orifice plate.The study covered jet at Rej=5000-20000;the initial crossflow rate Gc/Gj =0-1.3;and nondimensional jet-to-surface spacing Zn=1.5

2

2.5

3.The experimental results show that the impingement heat transfer from the rib roughened surface will be improved by increasing the initial crossflow rate.The heat transfer characteristics are considerably affected by the jet-to-surfaces spacing

and there exists an optimum.The effect of relative position of jet hole to ribs on heat transfer has been observed.