离心式压气机出口动态压力的关联维数特征分析

基于相空间重构理论,以800 kW离心式压气机在不同工况下的出口动态压力为研究对象,分析了其时域、频域和关联维数特征,目的是实现喘振识别。结果表明:系统稳态时,动态压力幅值小且随机特性强,系统的混沌特征较为明显。此状态下的关联维数曲线波动很大,饱和关联维数也较大(8~20),并且部分时段不存在饱和关联维数。而随着系统经过过渡过程进入喘振状态,压力幅值逐渐增大,频谱向低频段集中,表现出明显的周期特征,自相似特性增强。并且,关联维数曲线波动减小,饱和关联维数也相应减小。当进入喘振时,关联维数快速收敛到2左右并保持稳定,饱和关联维数也维持在2左右。在引入干扰信号的仿真实验结果显示,此方法的抗干扰性能较强,可以有效地判断离心式压气机的工作状态。

Correlation dimension characteristics analysis of dynamic pressure at centrifugal compressor outlet

In order to distinguish surge, the characteristics of dynamic pressure in time-domain, frequency-domain and correlation dimension were captured after analyzing the dynamic pressure at outlet of a 800 kW centrifugal compressor based on phase space reconstruction. The results showed that, as the centrifugal compressor worked under stable state, the amplitude of dynamic pressure was low with strong random characteristic and obvious chaotic features. In stable state, the correlation dimension curve fluctuated greatly, the saturated correlation dimension was also large (8~20), and there was no saturated correlation dimension in some periods. However, as it changed to transition state from a stable state, the pressure amplitude increased gradually, and the frequency spectrum was concentrated to the low frequency with obvious periodicity and self-similar characteristics. In addition, the fluctuation of the correlation dimension curve decreased, and the saturation correlation dimension decreased as well. When the compressor entered surge, the value of correlation dimension quickly weakened to 2 and remained steady, while the value of saturation correlation dimension kept 2 as well. Moreover, consistent properties were shown graphically for the randomly shuffled data. As a conclusion, the proposed method has strong anti-interference performance and can be used to feasibly identify the working status of a centrifugal compressor.