进口导流叶片对转子叶片颤振特性的影响

Investigations on flutter characteristics of rotor blade with IGV/fan interactions

关键词:  涡轮机  进口导流叶片  非定常气动力  颤振  强迫响应

Key words:  Turbomachinery  IGV  Unsteady aerodynamics  Flutter  Forced response

摘要:

上游静子叶片的尾迹扰动是下游转子叶片发生强迫响应问题的主要原因,但通常认为不会对颤振特性产生影响。运用CFD技术求解非定常流场,用能量法对典型涡轮风扇NASA Rotor 67进行了气动弹性分析。结果表明:不加进口导流叶片时其叶片最有可能在第二阶模态、60°叶间振动相角的情况下发生颤振;加上IGV(进口导流叶片)后,IGV的尾迹会显著改变转子叶片的颤振特性,当转子叶片的最危险颤振模态频率接近IGV尾迹的扰动频率时,即使单独转子叶片十分稳定,但在尾迹的激励下颤振仍然可能发生;当该频率远离IGV尾迹扰动频率时,尾迹扰动同样会使转子叶片气动阻尼降低。该结果意味着尽管IGV的引入不会明显改变压气机性能,但有可能会对其颤振特性带来明显的负面影响,需要在涡轮机设计中予以考虑。

Abstract:

It is widely known that the upstream wake is a major contributor to the forced vibration of rotor blades,but seldom noticed its influence on flutter characteristics.The present research performs aeroelastic analysis on a typical turbofan NASA Rotor 67 by CFD technique and energy method.The results indicate that the most dangerous flutter mode of the rotor blades is the second bending mode with IBPA=60°without IGV.While analyzing the rotor with IGV,the wake changes the flutter characteristics of the rotor blade significantly.If the natural frequency of the most dangerous flutter mode of the blade is close to the IGV passing frequency,flutter may happen even it is stable without IGV.For a mode whose natural frequency is far away from the IGV passing frequency,the wake may also drive the vibration to be unstable.Though the IGV does not influence the performance of the rotor much,it does add significant nonlinear effects to the flutter behavior of the rotor blades.Designers need to consider the coupling effects between IGV and rotor to avoid the significant change of the flutter boundary.