Research on mechanism of flow excursion in narrow rectangle channel under natural circulation

By changing the heating power, flow excursion happens in the laboratory equipment of natural circulation. Meanwhile, there is a certain degree of local flow oscillations before the happening of flow excursion. Based on analyzing the mechanism of flow excursion, it comes to that the change of bubble and flow pattern has effect on flow excursion. At early stage, the impact of resistance on bubble is significantly greater than that of buoyancy; at later stage, the resistance equals to the buoyancy, flow excursion stops. Channel effect has important promotion to flow excursion.

► We found the phenomenon of flow excursion in narrow rectangle channel under natural circulation.
► By experiment, we found the effect of narrow channel is a significant role in promoting flow excursion.
► we established the mechanism of flow excursion in narrow rectangle channel under natural circulation.