| The turbine shroud block is located between the turbine blades and the casing to protect and support the casing.With the continuous improvement of engine performance,the turbine’s inlet temperature continues to increase,and a more effective cooling structure is required.Trapezoidal grooves make a certain impact on the distribution of cooling film.Based on this background,this paper studied numerically and experimentally the impact of the film hole spacing,hole row spacing,the forward and backward combinations with two rows of holes,and analyzed the film cooling characteristics of the overall shroud block.In the double-row hole experiment,the film is susceptible to the influence of surface grooves,and more biased toward the groove direction.The effect decreases as the blowing ratio increases.At low blow ratios,the forward hole film cooling effectiveness is higher;at high blow ratios,the reverse hole film cooling effectiveness is higher.The discharge coefficient experiment results show that with the increase of the hole row spacing,the discharge coefficient gradually rises,the suppression effect of the secondary flow gradually decreases,and the suppression effect of the forward hole is more obvious.Numerical simulation results show that too large hole spacing leads to weaker superposition effect between rows.The reverse jet has a higher film cooling effectiveness at a large blow ratio,and the forward jet has a higher air film cooling efficiency at a low blow ratio.The film cooling experiment results of the shroud block show that the middle and upstream film holes have lower cooling effectiveness,and the downstream film holes have higher effectiveness due to the superimposition effect of the upstream holes.The larger the blowing ratio,the more obvious the effect.The best blowing ratio of the flat-4×10-hole-array is 1.1,and the best blowing ratio of the grooved-surface-3×9-hole-array is 1.4.The secondary flow of the grooved-surface-3×9-hole-array is more susceptible to the suppression effect,and the discharge coefficient is smaller than the flat-4×10-hole-array on the same blow ratio.Numerical simulation results show that the gas film on the plate is easily affected by the direction of the main flow;the gas film is more inclined to the groove direction.When the blowing ratio increases,the upstream film hole efficiency decreases,and the downstream hole efficiency increases. |
