Experimental study on Ledinegg flow instability of two-phase natural circulation in narrow rectangular channels at low pressure

Ledinegg flow instability of two-phase natural circulation has been experimentally investigated based on a natural circulation device with narrow rectangular channels. When heating power reaches a certain range, the Ledinegg flow instability occurs in the system, accompanied by flow oscillation. The stability of the experimental system increases with the increasing of inlet sub-cooling, pressure and size of rectangular channels. Stability boundaries of the system are obtained by the sub-cooling number and the phase change number. It is discovered that there are 4 stages of Ledinegg flow instability in the narrow rectangular channels: condensation, ebullition, choking, and rebalance. Finally, the experience correlation is proposed for the initial power of Ledinegg flow instability in narrow rectangular channels.