Turbulence modeling for flow in a distribution manifold

An investigation of candidate turbulence models for application to the flow in a distribution manifold has been performed by a synergistic combination of numerical simulation and laboratory experiments. The investigated manifold was a cylindrical chamber fitted with an array of discharge slots deployed axially and uniformly along the length of the chamber. Three turbulence models were considered for the numerical simulations: standard k–ϵ, renormalized group k–ϵ (RNG), and realizable k–ϵ (REAL). The numerical predictions obtained from the application of these models were compared with the experimental results, and the REAL model was found to provide the best representation of the data. Special attention was given to the pressure variation along the length of the manifold, the per-exit-slot mass discharge, and the angle at which the exiting mass leaves the manifold. The departure angle is related to the axial momentum carried by the exiting flow. As confirmed by both the numerical simulations and the experiments, the departure angles varied from 68 to 90° from the upstream end to the downstream end of the manifold (90° is perpendicular to the axis). An in-depth study of numerical accuracy was performed encompassing number of nodes, deployment of nodes, and positioning of the solution domain.