高负荷弯掠叶片力学模型与应力抑制研究

Mechanical Modeling and Stress Suppression on

关键词:  弯掠叶片  结构特征参数  离心载荷  附加力矩  应力分布

Key words:  Swept blade  Characteristic parameter  Centrifugal load  Additional moment  Stress distribution

摘要:

几何构型对叶片应力的影响规律是高负荷弯掠叶片应力优化的关键。建立了带有弯掠与扭曲结构特征参数的叶片力学模型，研究了掠形与扭转构型对叶片应力分布的影响。结果表明:弯掠造成的附加弯矩与叶型截面形心位置紧密相关，弯曲应力极值可能出现在叶型前缘、尾缘和叶背中部三个区域；扭转造成的附加扭矩的大小由叶尖到叶根逐渐增加，在叶片自然扭曲率较小时，附加扭矩为负方向，其作用致使叶片解扭；对于典型弯掠叶片，其离心力作用下的径向力载荷决定着自身的截面平均应力水平，而附加弯矩和扭矩载荷决定着截面的应力分布形式。在给定的叶型条件下，可通过掠形方式的调整使附加弯矩与扭矩相抵消，降低叶片峰值应力30%以上。

Abstract:

The rules of effects of configuration on blade stress are key to high loading swept blade stress optimization. A mechanical model of blade with characteristic parameters of sweep and torsion was constructed. Effects of blade sweep and torsion on stress distribution were studied. It turns out that the additional moment caused by sweep is closely related to the location of blade section centroid. Extreme moment is most likely to appear in the leading and trailing edge of the blade profile and the middle of the suction surface. The additional torque caused by torsion gradually increases from blade tip to root. The torque turns negative when the torsion ration is small and it decreases the blade torsion. For typical swept blade，the stress level is mainly determined by the radial force while the stress distribution is determined by the additional moment and torque. In certain blade profile condition，the effects of additional moment and torque could be offset by sweep configuration modification，and the peak value of the stress could be reduced by more than 30%.