Three-dimensional numerical investigation of laminar flow in blind-tee pipes

Blind-tee pipes are often employed in process piping systems used in offshore and subsea oil and gas industry. The objective of the present study is to investigate the effects of blind-tee length, end-structure shape and flow velocity on the mixing condition inside blind-tee pipes. Three-dimensional numerical simulations are performed for the laminar flows in the pipes with blind-tee length varying from 1D to 5D at Re = 500, 1000, 1500 and 2000. Spherical and flat end-structure shapes are also investigated for the blind-tee section. Firstly, flow simulations in a straight pipe are performed, and the numerical results are compared with the analytical solutions. Then, the computed velocity profiles are used as the inlet velocity for the simulations of blind-tee pipes. Flow characteristics both inside and downstream the blind-tee section are numerically studied by analyzing the streamlines, pressure contours and velocity profiles. The results reveal that a higher inlet velocity and a blind-tee length no more than 3D can achieve a better mixing condition for the fluid flow in blind-tee pipes; while stagnant flows are more prone to occur towards the end of the blind-tee section at low velocities with the length longer than 3D, leading to potential fluid deposition in blind-tee pipes.