Document Type


Date of Degree

Spring 2011

Degree Name

MS (Master of Science)

Degree In

Civil and Environmental Engineering

First Advisor

Odgaard, A. Jacob

First Committee Member

Weber, Larry J.

Second Committee Member

Papanicolaou, Athanasios N.


Vortex drop shafts are used to transport water or wastewater from over-stressed existing sewer systems to underground tunnels. During the plunge a large amount of air is entrained into the water and released downstream of the drop shaft into the tunnel. This air is unwanted and becomes costly to treat and move back to the surface. Determining the amount of air that will be entrained is a difficult task. A common method is to build a scale model and measure the air discharge and scale it back to prototype. This study investigated a possible relationship between the geometry of the drop structure, the water discharge and the amount of air entrained. The results have shown that air entrainment is still not entirely understood, however we are close to a solution. Using a relationship of the air core diameter, drop shaft length and terminal velocity of the water, a likely exponential relationship has been developed.


Air Entrainment, Drop Shaft, Drop Structure, Scaling, Vortex


vii, 45 pages


Includes bibliographical references (pages 40-41).


Copyright 2011 Cody N. Pump