For the purpose of improving the film-cooling effectiveness on blade tip region of gas turbine

numerical simulation was carried out on the blade tip model to investigate the flow and heat transfer for four kinds of cooling holes. It was found that the covered structure can double the film-cooling effectiveness compared to the uncovered structure for aclinic injection structure.The physics was revealed by analysis of the flow filed

and results showed that the aclinic injection can improve flow distribution

obtain better film-coverage and more uniform flow distribution

consequently increasing the film-cooling effectiveness.The effect of gap width

cover degree

cover thickness and fence on film-cooling effectiveness was studied

and the results showed that the increase of the cover degree and decrease of the gap width can get a higher film-cooling effectiveness

but the cover degree and gap width were restricted by structural strength

technological level and secondary flow inlet pressure.Aclinic cover can obtain a better film-cooling effectiveness than the inclined one and there is a best cover thickness enabling to obtain the highest film-cooling effectiveness for the aclinic one.Sufficiently long fence can improve the flow distribution and increase the film-cooling effectiveness.