为了考虑叶轮机叶片结构与流体之间的耦合效应,同时提高叶轮机颤振数值研究的效率,发展了一种基于非定常气动力降阶模型(ROM)的叶栅耦合颤振分析方法.该方法运用时域计算流体力学(CFD)技术计算少数几个叶片的非定常气动力,通过系统辨识及一些假设构建整个叶栅振动的非定常气动力降阶模型,并在状态空间耦合叶栅结构动力学方程建立叶栅气动弹性方程,采用特征值和时域仿真分析该系统稳定性.运用该降阶耦合方法对STCF4(StandardTest Configuration 4)以及NASA Rotor67叶栅系统的稳定性进行了计算.通过与直接计算流体力学/计算结构动力学(CFD/CSD)耦合方法和非耦合方法计算结果的比较验证了该方法的准确性,且该降价耦合方法的计算效率相对于直接CFD/CSD耦合方法提高了1~2个量级,为叶轮机气动弹性参数研究、失谐研究以及多模态耦合计算等提供了便利.
As direct numerical simulation of fluid/structure interaction of entire blade row is computation-intensive and time-consuming,this paper presents a reduced order model (ROM)-based coupling method which takes fluid/structure coupling effect into account and provides a significant increase in efficiency of flutter analysis of turbomachinery.This method computes unsteady aerodynamic forces of several blades in time domain by computational fluid dynamics (CFD) technique,and then constructs the reduced order aerodynamic model of entire vibrating cascade with system identification and several assumptions.And finally,this method establishes the aeroelastic model of entire cascade by coupling the reduced order aerodynamic mode with cascade structural dynamic equation in state-space form.Flutter characteristics of STCF4 (Standard Test Configuration 4) and NASA Rotor67 cascade are analyzed by solving eigenvalues of the aeroelastic model.The accuracy of this method is validated by comparing the results of direct computational fluid dynamics/computational structural dynamics (CFD/CSD) coupling method and uncoupled method.The ROM-based coupling method improves computational efficiency by nearly two orders of magnitude compared to direct CFD/CSD coupling method.Besides,this method provides an effective and reliable approach for parameter analysis,mistuning and multi-mode coupling calculation of turbomachinery.