A 3D CFD model analysis of the hydraulics of an outfall structure at a power plant

A practical application of a three-dimensional (3D) computational fluid dynamics (CFD) model to an outfall structure of a power plant is presented in this paper. The outfall structure, used for discharging 55 m³/s of cooling water to a reservoir, consists of two inflow pipes, two deflectors and a baffle wall. The computational grid, resolving all the geometric features of the outfall structure consists of 350,660 hexahedral cells. The CFD model was run for two configurations of the outfall structure, with and without a baffle wall. The interactions of two high velocity jets with deflectors and baffle wall create complex velocity distribution and circulation patterns. Initially, both the jets bifurcate and then merge as they propagate downstream. At the outlet, the maximum near-surface velocities are not significantly different for the two configurations of the outfall structure. However, when the baffle wall is used the near-bed velocities, responsible for reservoir bed scouring, are approximately 75% smaller.