Lock Manifold Port Coefficients

INTRODUCTION: The U.S. Army Corps of Engineers (USACE) is responsible for the nation’s inland navigation infrastructure. Navigation locks are an essential asset to the waterway system, and hydraulic design of new locks and extension of existing locks, as well as assessment of locks in operation, require evaluation of the locks’ manifolds. Hydraulic evaluation of a lock manifold requires the calculation of flow rate and pressure distributions throughout the manifold. A set of energy equations (one written for flow through each port) and the continuity equation provide a means of calculating the flow distribution. 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 (1942). 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. The purpose of this technical note is to provide a single source of loss coefficient information for lock manifold ports. Coefficients have been gathered from technical reports, laboratory experiments, and computational models. The sizes and shapes of culverts and ports are described using dimensionless terms. This technical note includes loss coefficient information required for hydraulic analysis of manifold flow. PORT HEAD LOSS: Hydraulic and geometric variables in the vicinity of a single port are defined in Figure 1. The head loss as flow passes from the culvert to the lock chamber through a port is shown as ΔH' in Figure 1. The head loss for flow through individual ports of the manifold can be computed in terms of the culvert velocity head as: