A High Efficient Fluid-Structure Interaction Method for Flutter Analysis of Mistuned

叶轮机失谐叶片流固耦合颤振高效分析方法

¹ School of Aeronautic Engineering, Zhengzhou University of Aeronautics, Zhengzhou 450046, China
² CECCS Sichuan Gas Turbine Establishment, Chengdu 610500, China
³ National Key Laboratory of Aerodynamic Design and Research, Northwestern Polytechnical University, Xi’an 710072, China

Received: 9 September 2017

Abstract

The time cost is very high by direct fluid-structure interaction method for mistuned bladed disk structures, so aerodynamic loads generally are ignored or treated as small perturbations in traditional flutter analysis. In order to analyze the flutter characteristics of mistuned blade rapidly and accurately, this paper presents an efficient fluid-structure interaction method based on aerodynamic reduced order model. system identification technology and two basic assumptions are used to build the unsteady aerodynamic reduced order model. Coupled the structural equations and the aerodynamic model in the state space, the flutter stability of mistuned bladed disk can be obtained by changing the structural parameters. For the STCF 4 example, the response calculated by this method agrees well with the results obtained by the direct CFD, but the computational efficiency is improved by nearly two orders of magnitude. This method is used to study the stiffness mistuned cascade system, and the stability characteristics of the system are obtained by calculating the eigenvalues of the aeroelastic matrix. The results show that the stiffness mistuning can significantly improve the flutter stability of the system, and also lead to the localization of the mode. The mistuning mode, mistuning amplitude and fluid structure interaction can influence the flutter stability obviously.

摘要

直接流固耦合算法耗时极大，因此传统的失谐叶盘结构系统颤振研究一般将气动力忽略或将其当成小扰动。为了快速、准确分析叶轮机失谐叶片的颤振特性，基于气动力降阶模型提出了一种高效的叶轮机失谐叶片流固耦合分析方法。该方法利用系统辨识技术和一些基本假设来构建叶栅非定常气动力降阶模型，并在状态空间内耦合结构运动方程，得到气动弹性模型，通过改变部分叶片的结构参数来研究失谐对系统流固耦合颤振稳定性的影响。针对STCF 4算例，该方法计算得到的响应结果和直接CFD的结果吻合良好，但计算效率却提高了近2个数量级。运用该方法研究叶排系统的刚度失谐，通过求解气动弹性矩阵的特征值快速获得了系统的稳定性特征。结果表明，刚度失谐可以明显改善系统的颤振稳定性，也会导致模态局部化。失谐方式、失谐量和流固耦合作用对失谐后系统的颤振稳定性都有明显影响。