A transient liquid crystal technique was used to measure the local heat transfer coefficients on a target surface with array impingement hole. The effects of jet Reynolds numbers (5000

10000

15000

20000) and the ratios of the side bleeding(0

0.25

0.4

0.6

0.8

1) on the heat transfer coefficients were investigated. Results show that

the heat transfer coefficients on the target surface rise with the increase of jet Reynolds number; the heat transfer coefficients on the impingement stagnation regions are the highest

and the heat transfer coefficients on the film holes regions are also relatively high. The average heat transfer coefficients on the target surface decrease with the increase of the ratio of the side bleeding

and are not strongly influenced with the low ratio of side bleeding

but significantly affected with the high ratio of side bleeding.