中文摘要：

对摇摆条件下两相自然循环系统不规则复合型脉动进行了非线性时序分析。通过相空间重构计算了不规则复合型脉动时间序列的关联维、K2熵和最大Lyapunov指数值,在几何不变量的计算结果基础上,结合密度波型脉动和波谷型脉动的对比,分析了不规则复合型脉动的混沌特征和产生机理。分析结果表明：不规则复合型脉动为典型的混沌运动,热驱动力、流动阻力和摇摆引起的附加外力的相互作用和耦合导致了混沌的出现。

英文摘要：

Non-linear time series analysis on irregular complex flow oscillations of natural circulation system under rolling motion was studied.The correlation dimension,K2 entropy and maximal Lyapunov exponent（MLE） were determined based on phase space reconstruction theory.The chaotic features of the irregular complex flow oscillations were analyzed by comparing with density wave oscillation and trough-type flow oscillation base on the results of geometric invariants.The results indicate that irregular complex flow oscillations are typical chaotic oscillations,the interaction and feedback of thermal driving forces,flow resistance and additional forces caused by rolling motion lead to the emergence of chaos.