The thermal image visualization of jet impingement cooling with single or double rows of holes inside the semi-enclosed channel were revealed by using infrared camera and then the impingement cooling heat transfer coefficients were deduced.The effects of flow and geometric parameters on convective heat transfer coefficients were obtained.The results show that: for a single row normal impingement

the impingement cooling effectiveness is enhanced with the increase of impinging Reynolds number or the decrease of hole spacing to diameter ratio

and the best effectiveness is achieved under the jet-to-surface spacing equals to 2;when the jet is oblique to the confined wall

the cooling effectiveness is weakened especially when the jet-to-surface spacing ratio is greater than 2;for double rows of holes with normal impingement cooling

the cooling effectiveness of rear row jets is weaker than the front row jets at lower impinging Reynolds number or larger jet-to-surface spacing.