Simulation Experiment And Model Calculation Of Fluid Mixing And Stratification In Large Space

Mixing and thermal stratification often appears in large space which has internal heat source. For nuclear power plant, the space of containment is large, thermal stratification can occur after break accidents such as LOCA(Loss of Coolant Accident) or MSLB(Main Steam Line Break). Thermal stratification has important effects on containment external heat dissipation. For API000 reactor, passive containment cooling system is a vital way to release heat to the environment, so an accurate prediction of distribution of temperature or density In large layered space plays an important role on the reactor optimization design and safety analysis.At present, the analysis of distribution of temperature field in containment mainly relies on some calculation software, which has many issues such as poor calculation accuracy and long calculation time. In order to evaluate the reliability of software calculation, broaden software application scope and develop a more accurate calculation model, experimental data must be relied as a strong technical reference.When LOCA or MSLB occurs in containment, the radius, position, angle, flow and temperature of the break can affect the containment mixing and thermal stratification. This paper builds a visual glass containment test bench to simulate the mixed convection heat transfer phenomena in containment caused by break accidents such as LOCA or MSLB. The glass containment is full of saline water with a larger density, dyed water is injected to the containment from the bottom through a thin nozzle to simulate the break injection under the conditions of LOCA or MSLB. The flow of dyed water is observed to study the mixing and thermal stratification process caused by break. In addition, this paper studies the influence of height of the break, horizontal position, flow and fluid temperature on stratification, and makes comparative analysis with numerical simulation results.