基于有限元方法，建立了含质量慢变的双跨转子系统动力学模型。运用Newmark-β数值积分方法，通过轴心轨迹图、Poincaré截面图、时域波形图、频谱图和三维瀑布图等，对双跨质量慢变转子系统在不同转速、不同慢变参数和不同慢变位置情况下的振动特性进行分析。结果表明，当系统存在质量慢变时，在工频的ε倍处会出现慢变小分频Fr，且在工频两侧以及Fr的右侧出现以ε•Fn为频率间隔的等距分频；质量变化幅值系数主要影响转子系统的幅值，当λ逐渐增大时，系统的各个频率成分的幅值均有增加，系统变得越来越不稳定；慢变时间系数主要影响转子系统的周期性，当ε发生变化时，系统的周期运动倍数和周期长短明显变化；双跨双盘转子系统的两个盘均存在质量慢变时，系统的周期运动和分频成分由两盘叠加而成，且高转速区附近的现象变得更加明显。研究结果为今后质量慢变转子系统动力学与故障识别研究提供一定的理论参考。
Abstract
Here, based on the finite element method (FEM), a dynamic model of a double-span rotor system with slowly varying mass was established. By using Newmark-β numerical integration method, vibration characteristics of the double-span rotor system with slowly varying mass under conditions of different rotating speeds, different slowly varying parameters and different slowly varying positions were analyzed with shaft center trajectory diagram, Poincaré section one, time domain waveform one, frequency spectrum one and 3-D waterfall one. The results showed that when there is a slowly-varying mass in the system, a slowly-varying small frequency division Fr appears at ε times of working frequency, and equidistant frequency divisions with frequency interval of ε•Fn appear on both sides of working frequency and on the right side of Fr; the mass variation amplitude coefficient λ mainly affects vibration amplitude of the rotor system, when λ gradually increases, the amplitude of each frequency component of the system increases, and the system becomes more and more unstable; the slowly-varying time coefficient ε mainly affects the periodicity of the rotor system, when ε changes, multiple and period length of the system periodic motion change significantly; when both two disks of a double-span and dual-disk rotor system have slowly-varying mass, the periodic motion and frequency division components of the system are composed of the superposition of the two disks’, and phenomena near high rotating speed region become more obvious; the study results can provide a theoretical reference for studying dynamics and fault recognition of rotor systems with slowly varying mass in the future.
关键词
双跨转子系统 /
质量慢变 /
有限元法 /
动力学特性
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Key words
double-span rotor system /
slowly varying mass /
FEM /
dynamic characteristics
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