Modeling Flow through a Lock Manifold Port

BACKGROUND: Manifolds are essential components of a navigation lock’s filling and emptying system. They are used as intakes, outlets, and lock chamber filling and emptying culverts. Evaluation of a lock system requires an understanding of the hydraulics of manifolds. Analytical solutions of lock manifold flow are given by Stockstill et al. (1991), Allen and Albinson (1955), Webster et al. (1946), Soucek and Zelnick (1945), and Zelnick (1941). One-dimensional (1-D) numerical flow solvers such as LOCKSIM (Schohl 1999) are also used to calculate the flow and pressures in lock manifolds. Each of these evaluation techniques requires knowledge of energy loss coefficients for multi-ported manifolds. Hydraulic coefficients for industrial manifolds which have common geometries such as tees and wyes are readily available in the literature (e.g. Miller 1990). However, the culvert and port shapes and sizes in lock manifolds are very different from typical industrial manifolds and vary from project to project. These structural differences make generalizing the solution of velocity and pressure distribution in lock manifolds impossible. Hydraulic coefficients for a limited number of port shapes have been determined from laboratory experiments using single-port models. Examples of single-port laboratory data are provided by Zelnick (1941) and Webster et al. (1946). Construction and testing of a laboratory model can be expensive. An economical alternative would be the use of a three-dimensional (3-D) computational flow model. This technical note describes the use of a detailed 3-D computational flow model to determine the velocity and pressure distribution in a single-port manifold for a range of port-to-culvert discharge ratios. The flow solutions are then used to calculate energy losses in flow exiting a manifold port. Finally, this energy loss information is presented in terms of head loss coefficients required for a 1-D flow analysis of a multi-ported manifold. This technical note documents the validity of using a 3-D computational flow model to obtain loss coefficient information required for manifold flow analysis. The modeling process is validated by comparing computational results with previously published laboratory data.