SIMULATION OF MIXING IN MULTI TEE JUNCTION GEOMETRY USING LES AND RANS MODEL

Abstract

In the T-junction, when two fluids mix at different temperatures, then generation of cyclical stresses takes place, and these stresses are responsible for the failure of pipe material because these stresses cause thermal fatigue. This difference in temperature causes frequent changes in temperature, which further results in unpredicted breakdown of material of pipe. As a result, with the purpose of knowing the lifetime of material of pipe, a precise prediction of alteration in temperature is mandatory. When fluids at different temperature mix then fatigue cracks develop at mixing tees. These failures are the reason that there is an increase in the investigation of thermal mixing problems in piping networks, because safety is a major issue in nuclear power plant. The flow in the T-junction is a demanding investigation for, the CFD techniques based on RANS, and Computational Fluid Dynamics(CFD)which are in general employed in industrial application have complications in giving precise results for this flow state. In case of thermal mixing in T-junction, hydraulic design (i.e dimensions and momentum ratios) of tee components is important. The magnitude and intensity of the thermal load are directly affected by the momentum ratio of hot and cold streams. Momentum ratios of streams can be controlled by pipe diameters or mass flow rates