Behaviors of Thermal Stratification Layer at Elbow in a Closed Branch Pipe

Abstract

Many pipes branch off from the main pipe in nuclear power plants. When the main flow in the main pipe is hotter than the fluid in a branch pipe that branches off downward, the hot water penetrates into the branch pipe with the cavity flow induced by the main flow and causes thermal stratification. Some experiments were conducted to elucidate the mechanism of this fluctuating thermal stratification. When the main flow was heated and the thermal stratification interface was at the elbow, "burst" phenomena occurred in the interface in connection with great heat fluctuation. Visualization of the temperature fluctuation phenomena caused by the "burst" phenomena was conducted by using thermo chronic liquid crystal.