Analysis Of Steam Generator Two-Phase Flow Instability Under Sinusoidal Perturbation

Steam generator is key equipment in nuclear power plants as a heat exchanger for connecting primary loop and secondary loop. It plays a vital role in the safe operation of the entire nuclear power plant. Because of the complex structural properties, flow and heat transfer characteristics, the steam generator has been the focus of domestic and foreign scholars. The damages of steam generator tubes are high incidence of accidents in nuclear power plants, studying two phase flow instability of steam generator has great value and practical significance for the safety of steam generator.In this paper, with reference to the experiment conducted by overseas scholars HT Liu and S. Kakae, establish physical model of vapor-liquid two phase flow. Built on the accurate theoretical model of the drift-flux, establish the mathematical model of vapor-liquid two phase flow. To establish a simulation model of vapor-liquid two phase flow by using Matlab/Simulink, use this simulation to conduct the steady-state simulation of different power,different mass flow rate, different inlet temperature. With step by a 10% decrease in mass flow rate and 10% descend in inlet temperature, conduct the dynamic simulation for 4 kinds of power. For two typical operating conditions in actual ships, rise load and load rejection,have been simulated here by using a simulation model with the heating power step increase and step decrease. With 5%, 10%, 15% of mass flow rate disturbance and 5K, 10K, 15K inlet temperature disturbance, conduct the instability simulation. With the disturbance of mass flow rate and inlet temperature under 600W, 800W, 1000W power, analyze the characteristics of two phase flow instability.Compared with the results of the steady state thermal calculations and found that simulation results is reasonable and reliable, the error scope between the main parameters of the steam generator calculated by simulation and the steady state thermal calculations is within the allowable range, which verifies the accuracy of the simulation model. Steady-state simulation got some major drift flux model parameters of the boiling section, the distribution parameter C0; the two-phase multiplier ?102; the slip ratio S, the steady-state simulation results of three representative parameters were reasonable. On the basis of the dynamic simulation for 4 kinds of power with step by 10% decrease in mass flow rate and 10% descend in inlet temperature, shows the higher the power, the higher the magnitude of change in preheating height, quality of gas. On the basis of the instability simulation for different ranges of mass flow rate and inlet temperature disturbance, shows the higher the disturbance, the higher the magnitude of change in the pressure, void fraction. On the basis of the instability simulation for different power of mass flow rate and inlet temperature disturbance, shows the higher the power, the higher the magnitude of change in the pressure; the lower the power, the higher the magnitude of change in mass flow rate.In summary, the simulation model based on the drift flux theory and the results of steady-state and dynamic simulation research, the results of instability simulation research,has a good reference value for conduct research on actual steam generator and has great value for improving the security of a real steam generator.