The behaviour of fluid flow in a 90-degree (sliced) nonlinear bend

Abstract

The behaviour of flow due to nonlinear bends in piping networks involves the occurrence of contractions and turbulence that begin when approaching the upstream part down to the downstream part; these conditions are caused by collisions between fluid particles flowing with pipe walls in sudden direction changes. Though contractions and turbulence occur in all directions along the bends, the normal flow downstream of the bends occurs quite far after the bends. The elements that influence contraction and turbulence are velocities (U), number of slices (n), length of nonlinear walls (Li), sudden angle changes (μ), coefficient of friction (f), acceleration of gravity (g), and the slope of the pipe base (I). A higher flow velocity in a pipe leads to farther laminar flow returns downstream of the bends, and a smaller flow velocity leads to the flow returning to normal downstream shortly after the bends. The simulations of this research involved a 10 m/s initial velocity with a 25.4 mm pipe diameter and the number of slices (n) = 2; normal flow was achieved at 22D after the nonlinear bend. With similar velocity and different diameters of pipes, the length of contraction, turbulence, and laminar flow were equal. This analysis is expected to provide optimal benefits for performance in the usage of nonlinear bends in activities related to piping networks, especially the primary network, which uses large-diameter pipes.