In order to study the evolution process and hydraulic characteristics of pressurizer insurge in CPR1000 pressurized water reactor (PWR), the computational fluid dynamics (CFD) of three-dimensional unsteady heat transfer was used to capture the temperature and velocity fluctuation intensity of the mixing of the hot and cold. The results show that Realizable k–ε Turbulence Model combined with VOF multiphase heat transfer model can effectively predict the development trend of pressurizer insurge process. The small diameter pressurizer surge line of CPR1000 enhances the intensity of velocity fluctuation. From the essence of flow and heat transfer, it is concluded that buoyancy force can increase the degree of fluctuation and make an accelerated effect on the influx cold fluid. The electric heater inside the pressurizer should be arranged as far as possible in z<-0.45m and z>0.45m; it is beneficial to improve its harsh operating environment. This research can provide reference for the structural design of pressurizer and the layout optimization of the electric heater.

This paper explores the windmilling operational boundary and aerodynamic characteristics of an axial wide-chord fan rotor according to the zero-torque characteristic. The interesting results show the radial profiles of the aerodynamic parameters at the rotor exit nearly collapse to the same curve for different windmilling speeds, which indicate that windmilling flow has a strong similarity. Meanwhile, there are three different operating modes along the blade span. The formation mechanism and evolution process of the tip leakage flow at the windmill are also analyzed. The reversal of the pressure difference will generate two kinds of tip leakage flows in opposite directions. A clear blockage zone appears near the blade tip under the joint action of the two kinds of tip leakage flows. Finally, this study proposes a mathematical model to predict the windmilling speed of a high-bypass-ratio turbofan based on the aerodynamic similarity of windmilling flow and the one-dimensional semiempirical windmilling mass flow function. This can be applied to the early stages of high-bypass-ratio turbofan development and can evaluate safety characteristics during engine windmilling operations.

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