【摘要】 本文以氟里昂12作工质,对自然循环过冷沸腾流动不稳定性进行了实验研究,实验过程中发现自然循环系统内可能发生高频脉动和低频脉动两类流动不稳定性,并证实高频脉动属于声波型脉动,低频脉动属于密度波型脉动。本文以两相流漂移模型为基础,对自然循环过冷沸腾流动不稳定性进行了数值模拟,数学模型考虑了热力学非平衡即过冷沸腾和过冷凝结对流动不稳定性的影响。数值模拟结果与实验结果符合良好。更多还原

【Abstract】 This paper presents both the experimental study and theoretical analysis of flow instabilityin a natural circulation system with subcooled boiling. Freon-12 was used as the working medium.It is found from the experiments that two kinds of flow instability, high frequency oscillations andlow frequency oscillations may occur in the natural circulation system with subcooled boiling. Thehigh frequency oscillations have the characteristics of acoustic oscillations, while the low frequencyoscillations belong to density wave instability. A mathematical model based on the drift flux modelhas been developed to analyze the subcooled two-phase flow instabilities in the natural circulationsystem. In the mathematical model, the modified Levy model is used to calculate the void fraction inthe heated section. The "Condensation-time" model is used to predict the void fraction in the unheatedriser. The finite difference equations are solved by using the SlMPLEC method. The caloulated resultsare in good agreement with the experimenial data.更多还原