Numerical simulation of turbulence mixing at T-junction piping system with elbow pipe in upstream side; Effect of secondary flow on temperature fluctuation

Tanaka, Masaaki  

In this report, numerical simulation using quasi-direct simulation code (DINUS-3) was carried out to investigate the effect of secondary flow upon the temperature fluctuation characteristics in the mixing region. The parameter was the angle of the elbow pipe flow direction to the branch pipe flow direction. By the numerical simulation, it found that the secondary flow had strong influence to the fluid mixing. Secondary flow changed the flow pattern of branch pipe jet and changed thoroughly the temperature fluctuation characteristics on the pipe surface, according to the angle. Attention should be paid to the arch-shaped large-scale eddies formed around the branch pipe jet in the thermal fatigue evaluation, because they played an important role for the fluid mixing. Furthermore, the range of about 2.0Dm from mixing point to the downstream should be focused for the evaluation of the thermal fatigue.