Hydraulic Modeling of Transmission Systems Using Spreadsheets

A design engineer's primary objective is to solve problems. Often a problem will have multiple solutions that need to be studied to determine the best answer. The required calculations may be complicated and/or redundant. In such cases, spreadsheets can be used to analyze multiple solutions efficiently and accurately, and to produce graphs that convey the solution to the client. Typically, water transmission projects consist of transmission pipelines and pump stations. The hydraulic models generated for the projects vary in complexity from simple hydraulic grade line calculations to rating curves and system and pump curves demonstrating the effects of numerous variables. Spreadsheet software is readily available and can be used for many applications, including hydraulic grade line calculations and graphing, system curve calculations and graphing, rating curve calculations and graphing, life cycle cost calculations, pump selection, multiple solution optimization, and appurtenance design calculations. Spreadsheets can be applied in situations where hydraulic modeling software cannot, including some life cycle cost analyses, development of system curves where a mix of gravity flow and pumped flow must be considered, comparison of multiple pump and driver speed combinations, and open channel flow in a pipeline within a transmission system. When using spreadsheets for hydraulic modeling, the equations used can be located and checked, and the variables are accessible and can easily be manipulated. The data, calculations, and exhibits can all be organized according to the user's preference, and graphs and tables can be customized to meet the client's needs. Most importantly, using a user-generated spreadsheet for hydraulic modeling requires the user to understand the system and what is happening hydraulically.