火焰筒掺混孔边裂纹萌生和扩展机理研究

Study on initiation and propagation mechanism of crack on dilution hole edge in combustor liner

利用有限元法,结合瞬态传热过程研究了火焰筒掺混孔内孔边裂纹形成和扩展机理,应用应变疲劳理论和裂纹扩展分析方法对裂纹萌生时间和扩展能力进行分析。由于火焰筒在热循环载荷作用下各处升温速度不一致,引起结构上的相互约束,使掺混孔边产生循环塑性变形导致疲劳裂纹萌生;裂纹萌生后会继续扩展,但这种扩展能力有限;孔边冷却区域大小会对裂纹扩展能力产生较大影响。

Using the finite element method （FEM）, theory of strain fatigue and stress intensity factor （K） , the crack initiation and propagation were analyzed. The rate of temperature rising on liner structure is not uniform under thermal cycling, which leads to mutual restraints inside of the liner and plastic strain cycling near the dilution hole, then the initial crack is generated following thermal cycles. The crack can grow gradually, but the ability of growth is limited and affected obviously by the size of cooling field around the hole.