自然循环过冷沸腾流动不稳定性的实验研究

Experimental Study of Flow Instability in a Natural Circulation System with Sub-cooled Boiling

以氟里昂作工质,对自然循环过冷沸腾流动不稳定性进行了实验研究。重点研究了流动不稳定性的发生机理以及系统操作参数对流动不稳定性的影响规律。实验结果证实,在自然循环系统内,多数运行工况下会同时发生高频脉动和低频脉动两类流动不稳定性。高频脉动属于声波型脉动,低频脉动属于密度波型脉动。通过实验得出了判断系统稳定性的界限,并使用积分方程无因次分析方法得出了预测流动不稳定性的准则关系式,利用准则关系式拟合实验数据,所得的经验公式与实验结果符合良好。

Experimental study has been performed to investigate the flow instability in a natural circulation system with sub-cooled boiling by using Freon-12 as the working medium. In the experiments, two kinds of flow instability, flow instability with high frequency and flow instability with low frequency, were found for most conditions. It is shown that the flow instability with high frequency belongs to acoustic oscillation and the flow instability with low frequency is density wave instability. In the experiments the effect of the parameters of the working medium on the onset of the flow instabilities in the system were investigated. The stability boundaries were determined through the experiments. By means of dimensional analysis of integral equations, the common correlations describing the threshold condition of onset of the flow instabilities were obtained.