自然循环流量漂移伴随动态振荡的机理分析

Theoretical Mechanism Analysis of Flow Excursion Companied by Dynamic Oscillation in a Natural Circulation System

在 5MW核供热堆试验回路HRTL 5上观察到了一定条件下系统发生的静态流量漂移并同时伴随动态流量振荡的现象。本文在实验基础上 ,研究了流量漂移的发生、发展和向动态振荡演变的过程 ,以及欠热沸腾、冷凝、闪蒸在此过程中的作用机理。分析结果表明 :1 )自然循环流量漂移是一个长热工过程 ,动态振荡可发生在静态漂移过程中 ;2 )在流量漂移的过程中 ,先是欠热沸腾和冷凝占主导地位 ,然后渐变为闪蒸占主导地位 ,最终表现为自持振荡形式 ;3)最终的自持振荡主要表现为密度波振荡 ,又具备喷泉不稳定的特征。

The flow excursion accompanied with flow oscillation phenomenon under certain conditions is observed in the heating reactor test loop of the 5 MW reactor. Based on the experimental investigation, the entire process of flow excursion from its beginning, developing and converting into dynamic oscillation is described and the mechanism of sub-cooled boiling, condensation and flashing, which act on the process, is analyzed too. The analysis result shows: 1) the static flow excursion is a rather long process, and dynamic oscillation can be found in it; 2) in the course of the flow excursion, the flow instability is first dominated by the sub-cooled boiling and condensation, and then is dominated by the void flashing, at last is the type of oscillation controlled by itself; 3) the final oscillation is mainly the form of density wave oscillation, meanwhile has the characteristics of geysering stablility.