不同孔间距下镍基单晶叶片气膜孔弹塑性行为研究

Crystallographic Behavior of Nickel Base Single Crystal Blades Film Cooling Holes under Different Hole Distances

气膜冷却作为一重要的热防护技术广泛应用于涡轮叶片中,但是气膜孔的引入破坏了叶片的结构完整性,成为裂纹形核的重要区域。将镍基单晶叶片前缘气膜孔简化为平板模型,基于晶体塑性理论分析了多孔干涉下气膜孔的弹塑性力学行为,分析了孔边分切应力的分布规律;并比较了不同横向、纵向间距对气膜孔弹塑性行为的影响。结果表明多排气膜孔间存在着明显的应力干涉,高应力区出现在相邻两列气膜孔孔心连线区域,低应力区出现在同列气膜孔之间,呈现菱形分布。孔边八面体、十二面体、六面体滑移系均开动,最大分切应力出现在夹角0o/20o/30o的位置上;横向孔间距增加,孔边应力降低;纵向孔间距增加,孔边应力增加。六面体滑移系分切应力对载荷、孔间距变化最为敏感。

Film cooling as an important thermal protection technology has been widely used in gas turbine blades.However,due to stress concentration around holes,the cooling holes have become key crack nucleation regions of blades.In this paper,the crystallographic behaviors of cooling holes were analyzed by the crystallographic constitutive model.Film cooling holes in the leading edge was simplified to a flat model.The distributions of resolved shear stress along cooling holes and changes under different hole distances were obtained.The results show that stress interference exits among cooling holes clearly.Higher stress areas appear between the centerlines of the cooling holes in two adjacent columns and the lower stress regions as a diamond-shape occur between two cooling holes in the same columns.All the slip systems of octahedral,dodecahedral and hexahedral will be active.And the maximum resolved shear stresses occur at the angle 0°/20°/30° of cooling hole.With horizontal holes distance increasing,the maximum stress around cooling holes decreases.With the vertical holes distance increasing,the maximum stress around cooling holes increases.In all the slip system,the hexahedral slip systems is the most sensitive to hole distances change.