A Simplified and Accurate Method of Computing Inlet Head of Multi-Outlet Pipelines

Abstract

The multi-outlet pipelines normally called as lateral lines are the major important components of the micro irrigation and sprinkler irrigation systems. To maintain the allowable discharge variation of the outlets, the variation in pressure along the length of the pipelines due to frictional head loss and elevation is restricted within a specified limit. In this process, the accurate computation of the inlet head of the lateral lines becomes necessary for proper design of the system. The generally used formulae of computing the inlet heads involve different values of coefficients quoted in literature without proper justification. This leads to over or under computed values of the inlet head. In this paper, equations are developed to accurately compute the value of the inlet head of lateral lines. The equations are based on the mathematical series of varying discharge from one outlet to other. The equations are simplified using mathematical logics and finally obtained in the compact forms to be used with the exponents of flow and diameter of different frictional head loss formulae. The verification and application of the formulae are illustrated with the standard example problems. The developed formulae can be easily and accurately used for computing the inlet head of lateral lines of micro irrigation and sprinkler irrigation systems.