含支承松动故障的航空发动机非同步响应特征
Characteristics of Aero-engine Asynchronous Response with Support Looseness Fault

针对航空发动机支承系统中普遍存在的松动故障，为研究松动故障导致的非同步响应特征产生的机理，建立了发动机的转子-支承-机匣整机模型，引入支承松动故障模型，利用数值积分方法求解耦合系统的响应，分析了非同步响应特征。结果表明，对于航空发动机中的支承松动故障，其引发的分频以及倍频原因在于，当刚度变化的周期等于转速周期时，将产生转频的倍频现象，在特定转速下，将激发系统的临界转速对应的频率；当刚度变化的周期等于n倍的转速周期时，则将产生1/n转频的分频及其倍频，在特定转速下，将激发系统的临界转速对应的频率。
This paper examines the mechanism of asynchronous response characteristics caused by looseness faults in aero-engine support systems. First, a single-degree-of-freedom rotor model without mass was established, and a looseness fault model was introduced. The response of the system was obtained by the numerical integration method, and the asynchronous response characteristics were analyzed. Second, an entire engine rotor-bearing-casing model was established, and a looseness fault model was introduced. The coupled system response was solved with the numerical integration method, and its asynchronous response characteristics were analyzed. The results showed the reasons that support looseness faults in aero-engines caused frequency division and frequency multiplication: When the changing period of stiffness was equal to that of the rotation speed, frequency multiplication appeared, and the corresponding frequencies of critical speeds were excited at certain speeds. Moreover, when the changing period of stiffness was integer times that of the rotation speed, 1/n times frequency division and frequency multiplication appeared, and the corresponding frequencies of critical speeds were excited at certain speeds.