Don J. Wood

An explicit algorithm for calculating operating parameters for water networks

Abstract An explicit methodology has been developed for use in comprehensive modelling of water distribution networks. The resulting algorithm is able to calculate directly the distribution system operating variables required to exactly meet specified operating conditions. Operating variables include pump speed, control valve settings, pressure regulating valve settings, and settings for flow limiting (pressure sustaining) devices. Specified operating conditions represent stated minimum pressure and volumetric flow requirements at designated locations throughout the distribution system. The proposed algorithm is shown to be robust and efficient, and guaranteed to converge in an expeditious manner. The wide range of capabilities and flexibility of the proposed approach are demonstrated using an example network. Enhancement of real-time modelling is a principal benefit of the methodology.

Using Variable Speed Pumps to Reduce Leakage and Improve Performance

It is well known that the use of variable speed pumps for operating pressurized water distribution systems provides many potential benefits. In this paper, several models for investigating the performance of water distribution systems with variable speed pumps are presented. The models were developed to determine the optimum speeds for operating VFD (variable frequency drive) pumps to meet stated objectives.

TRANSIENT FLOW OF SOLID-LIQUID MIXTURES IN PIPES

SUMMARY The basic relationships needed for a one-dimensional plane wave analysis of transient solid-liquid flow are presented. These relationships include expressions for pressure wave velocities and wave magnitudes and basic continuity and momentum expressions which must be applied after a pressure wave passes. Also viscous effects are considered including the momentum exchange between the phases due to viscous drag and the contribution of wall shear. Previously reported work dealing primarily with pressure wave velocities in solid-liquid flow and pressure and flow conditions adjacent to a boundary is reviewed. In this paper, the analysis is extended to any point in the flow system. The effects of viscous wall shear are considered. A basic relationship for flow continuity in an unbounded control volume is derived to study conditions after a pressure wave passes. Experimental results are presented which agree closely with the theoretical predictions. Highspeed movies were employed to record velocity histories in the transient flow.