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 number(5 000

10 000

15 000

20 000

25 000) and three different exit flow types on the heat transfer coefficients were also investigated.Results show that

the average heat transfer coefficient of target plate with double-sided flow is higher than that with single-sided flow;due to the different strengths of crossflow

the heat transfer coefficients on the target plate are also different.For each exit flow type

the local heat transfer coefficient increases with the jet Reynolds number over entire impingement target plate.