带锯齿形叶冠叶片接触应力计算及静强度分析

Contact stress calculation and static strength analysis of zig-zag shrouded blade

根据接触面位移收敛的特点,采用"位移提取法"计算锯齿形叶冠接触面的接触应力,在面网格尺寸为0.202 mm时可以得到准确的接触应力,最大值为453.48 MPa。分析了带冠叶片在不同情况下的应力水平和扭转程度,发现随初始安装紧度的增加应力水平增大,随离心载荷的增加叶片的扭转角度增大。根据接触面施加载荷与扭转角度的关系,得到了叶片的压缩刚度和扭转刚度,由于压缩刚度远大于扭转刚度,所以叶身应力制约接触面应力。提出以叶冠平均挤压应力不大于40%的名义屈服极限、叶片当量应力不大于75%的名义屈服极限作为静载荷强度判断准则进行静强度分析,初始安装紧度为0.127 mm时的带冠叶片模型可以满足该强度要求。

The"displacement extraction method"was proposed to calculate the contact stress of the zig-zag shroud contact surface according to the convergent displacement of contact surface.The contact stress can be obtained accurately with the surface mesh size of 0.202 mm,and the maximum value was 453.48 MPa.The stress level and torsion degree of the shrouded blade under different conditions were analyzed.The stress level increased with the increase of initial installation tightness,and the blade torsion angle increased with the increase of centrifugal load.According to the relationship between the load on the contact surface and the torsion angle,the compressional rigidity and torsional rigidity of blade were obtained.The compressional rigidity was much higher than torsional rigidity,so the stress of blade body restricted the stress of contact surface.It was proposed that the average contact stress of shroud should not be greater than 40%nominal yield limit and the equivalent stress of blade body should not be greater than 75%nominal yield limit as a criterion for the static load strength analysis,and the shrouded blade model of 0.127 mm initial installation tightness can meet this strength requirement.