Theoretical research on flow instability in parallel channels under motion conditions

In motion conditions, in addition to gravitational acceleration, a new acceleration was developed and it was added to the thermal hydraulics characteristics in flow channels. The additional acceleration leads to the different thermal hydraulic characteristics and will trigger the flow oscillation and even flow instability in parallel channels. In order to study the effect of the additional acceleration on the flow oscillation, the corresponding physical models are established in this work. Through the deduction of the mathematical model, the code for flow instability under motion conditions with Gear algorithm is developed. The flow oscillation curves, critical power, marginal stability boundary (MSB) are obtained. After comparison and analysis, it is found that some motion conditions lead to flow periodic oscillation. Different flow passage position results in different oscillation amplitudes. The marginal stability boundaries (MSB) under different motion conditions fit well, that is, the effect of motion conditions on MSB is small. Number of channels has little effect; however, channel arrangement influences the flow in every channel. These conclusions are of great significance in marine reactor design.