基于Lyapunov指数的摇摆条件下自然循环流动不稳定性混沌预测

Chaotic forecasting of natural circulation flow instabilities under rolling motion based on lyapunov exponents

运用基于最大Lyapunov指数的混沌预测方法对摇摆条件下自然循环系统的流量脉动进行了预测.对不规则复合型脉动的流量脉动实验数据进行相空间重构,计算关联维数、二阶Kolmogorov熵和最大Lyapunov指数等几何不变量,在说明不规则复合型脉动是混沌运动的基础上,根据最大Lyapunov指数对不规则复合型脉动进行了预测.通过预测结果和实验结果对比发现:对于复杂的两相自然循环流动不稳定性,预测结果具有较高的精度,说明预测方法的可行性.同时,确定了混沌系统可预测的尺度,提出用动态预测的方式监测系统流量脉动.本文的研究方法为两相流复杂的流动不稳定性研究提供了新的思路.

The chaotic forecasting of irregular complex flow oscillation of natural circulation flow instabilities under rolling motion condition based on the largest Lyapunov exponents is performed. The correlation dimension, Kolmogorov entropy and the largest Lyapunov exponent are determined based on the phase space reconstruction theory of experimental data. On the premise that the irregular complex flow oscillation is confirmed to own chaos characteristic, the chaotic forecasting of the irregular complex flow oscillation is carried out by calculating the largest Lyapunov exponent. A comparisons between the prediction results and experimental data indicates that the chaotic forecasting based on the largest Lyapunov exponent is an effective way of producing those two-phase natural circulation flow instabilities. Meanwhile, the maximum predictable scale of chaotic flow instability is determined and a way of dynamic forecasting to monitor flow oscillation is presented. The method employed here provides a new method of studying the complex two-phase flow instabilities.