燃气轮机叶片预扭叶冠应力计算与分析

Calculation and Analysis on the Pre-twist Shroud Stress of Gas Turbine Blade

以某型燃气轮机动力涡轮动叶为研究对象,通过仿真计算开展了预扭叶冠应力分布规律的研究。计算过程考虑了离心力载荷、压力载荷、热载荷、预扭约束的影响。计算结果表明:与无预扭约束叶冠相比,增加预扭约束后叶冠应力分布情况发生明显变化,大应力位置集中在预扭工作面与非工作面夹角位置,应力主要与离心力载荷和预扭约束有关。在离心力载荷作用下,叶冠有绕叶身进气侧旋转的位移运动;增加预扭约束后,抑制了叶冠的旋转,导致叶冠在夹角位置产生了附加应力;在叶冠夹角位置的应力由离心载荷产生的应力、预扭约束产生的应力与附加应力共同组成,为降低叶冠夹角位置的应力水平,需对叶冠厚度进行改进。

Taking the rotor blade of a certain gas turbine as research object, the regularity of stress distribution of pre-twisted shroud was studied.Through the simulation and calculation, the influence of centrifugal load, pressure load, thermal load and pre-twist constraint was considered in the calculation process.The calculation results show that the stress distribution of shroud is changed obviously when the pre-twist constraint is added, comparing with the shroud without pre-twist constraint.The location of large stress is mainly concentrated on the corner between the pre-twisted working face and non-working face, and the stress is mainly related with centrifugal load and pre-twist constraint.The shroud tends to rotate around the inlet side of the blade body under the effect of centrifugal load.After adding pre-twist constraint, the rotation of the shroud is inhibited, leading to the additional stress generated near the shroud corner.The stress near the shroud corner is composed of the stress generated by centrifugal load, the stress generated by pre-twist constraint and additional stress.In order to reduce the stress level near shroud corner, the thickness of the shroud needs to be improved.