强离心力影响下的叶轮裂纹故障定量建模方法与动力学机理研究

Centrifugal compressors are the key power equipment of large production units in the fields of metallurgy, petrifaction and energy. Crack faults in impellers occur frequently and have been serious problems of the corporations in these fields. Study on the mechanism of crack faults in impellers has been an urgent issue. This project studies the quantitative modeling method and dynamic mechanism of crack faults in impellers under the impact of strong centrifugal forces due to high speed of rotation. First, a model for breathing crack with gap is proposed to accurately simulate the nonlinear effects of gap caused by centrifugal forces. A quantitative method is also proposed for evaluating the mass eccentricity of structures with disequilibrium deformation, which is also caused by the centrifugal forces. Then, a complex component mode synthesis method with non-matching substructures is proposed for model order reduction of complex systems with non-proportional damping characteristic. This method provides an efficient way for constructing the quantitative models of cracked impeller-shaft systems. On this basis, the effects of crack fault in impeller on the vibration of the rotor are investigated, aiming at exploring response characteristics sensitive to the crack faults and establishing quantitative indicators for crack diagnosis. Finally, experimental studies are conducted to validate the proposed methods and the obtained results. The achievements of this project can provide valuable methods and techniques for diagnosing of the crack faults in impellers in the operating conditions. This project, concentrating on both theoretical significance and engineering applicability, will enhance the reliability and safety of centrifugal compressors.

离心压缩机是冶金、石化、能源等行业大型生产装置的核心动力设备，其叶轮裂纹故障频发，已成为相关企业面临的一大难题，亟待开展叶轮裂纹故障的机理研究。本项目研究高速旋转引发的强离心力影响下的叶轮裂纹故障定量建模方法及其动力学机理，提出考虑间隙影响的呼吸裂纹建模方法以及不均衡变形下结构质量偏心的定量评估方法，实现对强离心力引发的裂纹呼吸间隙非线性与动态不平衡效应的定量建模；提出适于复杂非比例阻尼系统模型降阶的非匹配界面复模态综合法，为含裂纹叶轮-转子系统定量分析模型的高效构建提供有效方法；研究叶轮裂纹故障对转子系统振动响应的影响机理，发现对裂纹损伤敏感的响应特征，建立有效的定量诊断指标；开展叶轮裂纹故障的实验研究，验证所提出方法与分析结果的有效性。研究成果可为运行状态下叶轮裂纹故障诊断难题的解决提供有价值的基础理论和关键技术，对于提高离心压缩机的可靠性与安全性，具有重要的学术意义和工程应用价值。

离心压缩机是冶金、石化、能源等行业的核心动力设备，其叶轮裂纹故障频发，已成为相关企业面临的一大难题，亟待开展叶轮裂纹故障机理研究。本项目围绕叶轮裂纹故障诊断难题，研究了强离心力影响下的叶轮裂纹故障定量建模方法及其动力学机理；提出了考虑间隙影响的呼吸裂纹建模方法，采用三维有限元模型和接触理论构建了裂纹叶轮结构的高保真分析模型，研究了离心力对裂纹界面间隙变化的影响特征，建立了融合间隙因素的呼吸裂纹模型；研究了离心力引发的结构不均衡变形特征，提出了基于单元质量矩叠加的结构质量偏心定量评估方法，研究发现裂纹导致的结构不平衡力与转速呈四次方关系；针对含裂纹叶轮-转子系统的高效建模问题，将复模态理论与非匹配界面子结构方法进行有机集成，提出了非匹配界面复模态综合方法，建立了复模态域中子结构模型降阶的坐标映射变换，构造了基于离散最小二乘法的非匹配界面节点匹配变换关系，以及基于界面模态坐标的非匹配界面位移协调条件，并用于含裂纹叶轮-转子系统的模型降阶；研究了裂纹故障对叶轮及叶轮-转子系统振动响应的影响规律，发现了裂纹对叶轮-转子系统耦合振动的影响特征；在此基础上，提出了基于模态畸变度的裂纹定位方法以及基于频率指标的裂纹定量识别方法，并开展了相关实验验证了方法的有效性。本项目研究成果为叶轮裂纹故障诊断与健康监测提供了有效手段，对于避免叶片断裂事故具有重要意义。