STIN special report 1:Loading to structures due to thermal stratification in a T-joint of hot and cold pipes

Thermal stratification of hot and cold water may cause damages in pipes of power plants. The main aims of this study are to improve the knowledge of the effects of thermal loads on the structures and to develop and verify a computational tool for numerical simulation of structural behaviour under a thermal stratification. A well-instrumented T-joint test section of hot and cold pipe is used for the experiments. In the hot horizontal pipe, the flow velocity is high, and therefore the flow is strongly turbulent. In the vertical cold pipe, the flow velocity is very small and the flow is laminar. Temperature, strain and displacement measurements will be carried out in order to get data to verify the numerical results. Preliminary results of the computational fluid dynamics (CFD) calculations are presented. Both the flow equations and the thermal conduction in the pipe walls and insulators are solved with the Fluent code. Transition from turbulent to laminar flow occurs near the T-joint in the cold pipe