Title

A study of hydraulic intake entrainment envelope delineation methods

Date of Award

2007

Degree Type

Thesis

Department

Civil and Environmental Engineering

Rights

CC BY-NC-ND 4.0

Abstract

Surface water has been a reliable source of providing municipal drinking water over the years by drawing water through hydraulic intake pipe. In this study, an effort is made to establish the entrainment envelope for the hydraulic intake pipe in a uniform cross-flow. The envelope is essential in defining the proportion of passing contaminants and flow ingested by the intake. An analytical delineation method--potential flow theory investigated the two and three dimensional flow solutions. The results were validated by numerical modeling of inviscid and laminar flow conditions; and velocity measurements obtained with laser Doppler anemometer confirmed the intake entrainment envelope as the immediate zone from which the water intake withdraws water. Comparison of the flow pattern, stagnation streamlines and velocity field plots show that intake entrainment envelope is characterized by a symmetrical half-body which increase in size with increasing intake discharge irrespective of the flow conditions. The entrainment envelope for viscous flow exceeded the inviscid radial flow in width and depth by distorting the entrainment envelope as a result of clockwise vortices found in the vicinity of the hydraulic intake for high intake withdrawal rates. The three-dimensional study confirmed these deductions and inferred the validity range for the potential theory and inviscid flow assumption.