起伏条件下自然循环密度波不稳定性研究

Study on Natural Circulation Density Wave Instability under Heaving Conditions

以自编程序运动条件下自然循环分析程序PNCMC研究起伏条件下两相自然循环密度波不稳定性。研究表明:起伏条件下自然循环系统会发生密度波流动不稳定性现象,起伏引起的流量振荡动与密度波振荡相叠加,最终形成复杂的复合振荡;在长周期(13、23 s)起伏时流量的振荡周期与起伏周期相等,但一个起伏周期内存在多次振荡;在短周期(3 s)起伏时,复合振荡存在着2种状态,低功率时的复合振荡周期性差,表现出不可预测的在某个起伏周期内振荡的突然增强;高功率时,复合振荡表现出较好周期性;起伏条件下系统稳定边界是整体上移,而且周期越小,上移量越大。

Two-phase natural circulation density wave instability under heaving conditions have been studied using PNCMC code （Program for natural circulation under motion condition）. Natural circulation density wave instability still occurred under heaving conditions, and the coupling of heaving motion and density wave instability induced much more complicated oscillation of mass flow rate. The period of complex flow oscillation was one heaving period under heaving with long period （13s, 23s）. However, there were two types of oscillation state under heaving with short period （3s）, for the cases of low heating power, the periodicity of flow oscillation was not significant; for the cases of high heating power, and the periodicity of flow oscillation was very significant. Heaving moved up stability boundary of natural circulation, the smaller the heaving period, the greater the amount of up.