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分别对40×5 mm和40×10 mm矩形通道内自然循环不稳定性进行了实验研究,得到了自然循环流量随加热功率的变化。结果表明:系统流量与压差的周期是相同并且反相;在矩形通道内,边角位置及二次流的存在,矩形通道会使流体的扰动加强,换热系数增加,特别是在饱和区域内,气泡与流体之间的扰动增强,容易形成搅拌流;5 mm通道与10 mm通道相比,由于其通道更窄阻力更大,在过冷区域更不容易形成稳定自然循环,且流动不稳定性的脉动更剧烈。
The instabilities of natural circulation in rectangular channels of 40 × 5 mm and 40 × 10 mm were studied experimentally, and the change of natural circulation flow with heating power was obtained. The results show that the periodicity of system flow and pressure difference are the same and reversed. In the presence of rectangular channels, the location of corners and the secondary flow, the rectangular channels will enhance the fluid disturbance and increase the heat transfer coefficient, especially in the saturated region Within the bubble, the disturbance between the bubble and the fluid is enhanced and a stirring flow is easily formed. Compared with the 10 mm channel, the 5 mm channel is less likely to form a stable natural circulation in the narrower and narrower the channel due to narrower channel resistance, and the flow is not The stability of the pulsation more intense.