To investigate the influence of small coolant jets on film cooling effectiveness

the distributions of the flow fields and cooling effectiveness with the small jets at different outlet placement under several blowing ratios were numerically studied.And the distributions were compared with the distributions of the baseline holes to reveal the good effects of the small coolant jets on the film cooling performance.The results show that

the new interaction between the weaker counter-rotating vortex pairs(CRVP) generated by the small jets and the CRVPgenerated by the main coolant jet weakens the mixing strength of the coolant jets with the hot cross flow

so the film effectiveness is higher with better coverage on the hot side under several blowing ratios.And the spanwise cooling effectiveness is improved significantly when the distance between the two small coolant jets is longer and the blowing ratio is higher.