中文摘要：

以去离子水为工质,对其两相自然循环流动不稳定性进行了实验研究,得到了2mm和5mm的矩形缝隙条件下的流量变化情况。实验结果分析表明：2mm矩形窄缝的流量波动周期为4~5s,5mm的流量波动周期为5~7s;2mm矩形窄缝的上下振幅对称性不佳,5mm的上下振幅对称性较好;随着加热量的增加,2mm和5mm矩形窄缝的波动周期均会增大。2mm矩形窄缝随着功率的增加,出现了流量漂移,密度波波动特征减弱。

英文摘要：

The experimental study was performed to investigate the flow instability in a natural circulation system by using deionized water, which gained the changeable situation of the flow rate in the narrow rectangle channel at the size of 2 mm and 5 mm. The analysis results show that the periods of wave with 2 mm and 5 mm narrow rectangle channel are 4-5 s and 5-7 s respectively, the symmetrical characteristic of the amplitude of 2 mm is not good as the 5 mm it is, and the periods of the 2 mm and 5 mm increase with the heating power. With the heating power increasing, flow excursion phenomenon happens in the channel at the size of 2 mm, and the characteristic of density wave weakens.