In order to explore the flow resistance characteristics of the bidirectionally expanded hole at both inlet and outlet

the discharge coefficients of the hole were experimentally studied under conditions with different jet angles and exit widths.In the experiments

the blowing ratio is 0.5

1.0

1.5and 2.0

and the mainstream Reynolds number is 6 500

10 000 and 13 500.The results show that

the jet angles had a weak effect on the discharge coefficient at blowing ratio of 0.5.While when the blowing ratio was 1.0

1.5and2.0

the discharge coefficient increased as the jet angle increased from 30°to 60°(the maximum growth was31%)

but it changed little as the jet angle continued to increase from 60°to 90°.When the ratio of exit width to the diameter of the film cooling hole increased from 1.5to 2.5

the discharge coefficient changed little at the blowing ratio of 0.5.While when the blowing ratio was 1.0

1.5

2.0

the maximum growth of the discharge coefficient was 18%

and the growth reduced as the jet angle increased.As the blowing ratio increased from 0.5to 2.0

the maximum growth of the discharge coefficients reached up to 107%.The mainstream Reynolds numbers had little effect on the discharge coefficients.