D221 T字配管合流部に生じる温度変動のLESによる評価 : 計算格子と上流境界条件の影響評価(OS6 保全・設備診断技術(6))

Thermal fatigue crack may initiate at mixing tee where high and low temperature fluids flow in and mix. In order to prevent piping failure caused by thermal fatigue, an evaluation procedure of fluid temperature fluctuation at mixing tee using numerical simulation has been developed. This paper compared simulation results of different grid resolutions and inlet boundary conditions. The simulation conditions were set same as WATLON experiments performed at Japan Atomic Energy Agency wall jet condition that the jet from the branch pipe flowed along the main pipe wall Coarser grid simulated lower temperature fluctuation intensity, probably due to larger subgrid scale viscosity. The temperature fluctuation intensity was the highest when both of velocity profile and velocity fluctuation were considered at the inlet boundaries of main and branch pipes, and this case was the most reasonable condition.