RESEARCH ON NATURAL CIRCULATION FLOW OSCILLATION EXPERIMENT IN NARROW RECTANGULAR CHANNEL

A narrow rectangular natural circulation experimental system is used to research flow pulsation occurred during the experiment. During the experiment, the flow pulsation phenomenon is found in narrow rectangular channels. When compared with density wave instability, it is found that the flow pulsation has certain characteristics of density wave instability, but at the same time, there will be a transient low flow phenomenon, which is a unique flow oscillation phenomenon in the narrow rectangular channel. The mechanism of flow oscillation phenomenon is analyzed, on this basis, a forecast equation of mass velocity is put forward. Forecast equation of mass velocity is used to calculate the natural circulation mass flow rate. Calculation results are in good agreement with the experimental results, which proves that the forecast equation of mass velocity is correct, provides control and prevention theory basis for natural circulation flow instability in narrow rectangular channel.