Experimental Study on Uncertainty of Scale-Down Methodologyfor Natural Circulation Steady-State Phenomena

Based on the H2TS scale-down method, three groups of experimental facilities, namely prototype, 1/2 model and 1/4 model, were designed and built. Natural circulation experiments on different pressures and heating were carried out. The uncertainty of the natural circulation steady-state characteristics in the reduced-height scale-down method is analyzed. The experimental results show that: The relationship curves between the dimensionless parameters such as Reynolds number, equivalent resistance coefficient, Grashof number and modified Grashof number, which represent the main characteristics of natural circulation, are not seriously distorted in reduced-height scaling simulation. The fitting curves of these dimensionless numbers between prototype and model can be mapped. The steady state characteristics of natural circulation can accurately reproduce the prototype in the process of scale-down proportional modeling.