Numerical Investigations of Turbulent Flow Through a 90-Degree Pipe Bend and Honeycomb Straightener

Pipe bends are commonly used in piping systems in offshore and subsea installations. The present study explores the design considerations for the honeycomb straightener inserted downstream of a 90-degree pipe bend. The objective of the study is to evaluate the effectiveness of the honeycomb in suppressing the flow swirling for different distances from the bend outlet (⁠$Lb$⁠) and different values of the honeycomb thickness (⁠$t$⁠). The turbulent flow through the 90-degree circular pipe bend with the honeycomb straightener is investigated by carrying out numerical simulations using the Reynolds-averaged Navier–Stokes (RANS) turbulence modeling approach. The explicit Algebraic Reynolds Stress Model (EARSM) is adopted to resolve the Reynolds stresses. The honeycomb thickness to pipe diameter ratio (⁠$t/D$⁠) is varied between 0.1 and 1. The normalized distance from the bend outlet to the honeycomb straightener (⁠$Lb/D$⁠) is varied between 1 and 5. The disturbance in the velocity field is generated by the pipe bend with the curvature radius to pipe diameter ratio $(Rc/D)$ of 2 and Reynolds number (Re) of 2 × 10⁵. It is found that both the increase in $Lb/D$ and $t/D$ improve the performance of the device in removing the swirl behind the bend outlet. The best performance is observed for the honeycomb straightener with the distance $Lb/D=5$ and thickness $t/D=0.5$⁠.