失谐叶片轮盘的减缩建模及动力响应预测方法

为解决高保真失谐叶盘计算量大的问题,提出了一种新的减缩建模及动力响应预测方法。该方法对叶盘单扇区有限元模型进行圆周对称分析,获取谐调叶盘在局部坐标系下的基本模态特性。同时,运用主节点的概念,仅对少量节点进行模态分析,在大大降低矩阵维度的同时获取准确的失谐模态特性。在动力响应预测分析时,利用失谐固有频率点处响应的基本特性,仅选取危险频段内、危险叶片上的危险节点进行响应分析计算,既极大地提高了运算效率,又能够准确地获取叶盘最大受迫响应幅值。实例分析结果表明:相较于传统的有限元方法,该方法中模态分析的求逆过程矩阵维度从150万下降到384,计算所得的前50阶固有频率的精度保持在0.005%以内,最大响应计算过程运算量下降超过99%时,仅存在-0.35%的误差。

Reduced-order modelling and dynamic response prediction method for mistuned bladed disks

In order to save the great computation effort for high fidelity mistuned bladed disk, a new reduced-order modelling and dynamic response prediction method for mistuned bladed disks is developed in this paper. Taking full advantage of cyclic symmetry of tuned bladed disk, a sector model is used to provide the primary information about dynamic properties in the local coordinate systems. Just doing model analysis on a small number of nodes utilizing the concept of "active nodes", the dimensions of operation matrices are reduced enormously but the model properties of mistuned structure are preserved with very high accuracy. In the process of dynamic response prediction, the response properties on the natural frequencies can be used for the choice of narrow frequency ranges, dangerous blades and nodes which need to calculate response. The main advantages are its efficiency and accuracy, which allow the high precision maximum forced responses. The results show that compared with traditional finite element method, the inverse matrices in this method are reduced from 1.5 million to 384, but the errors of the first 50 natural frequencies are limited in 0.005%. In addition, the computational complexity of maximum response calculation is lowered by more than 99%, which just produces -0.35% deviation.