CFD Modeling to Evaluate Design of an Intake of a Raw Water Pump Station at a Water Treatment Plant

A three-dimensional computational fluid dynamics model of an underground pump station with seven pumps operating at a total discharge of 175 MGD is presented in this paper. Each pump withdraws water through a 24-inch-diameter, 360-foot-long suction pipe in a 60-inch-diameter wet well that is connected to a horseshoe shaped conduit at a depth of 425 feet. The model domain includes a segment of a 9-footdiameter intake tunnel, conveying water from a lake, and a 30-foot-diameter surge tank. A high-density computational grid consisting of about 2 million polyhedral cells was developed to resolve the important geometric features of the system. The CFD model predicted steady state velocity, turbulence, and vorticity at several sections, including the pump bell throat. These parameters were analyzed in a manner analogous to that suggested by the Hydraulic Institute. Results indicate that the maximum swirl angle, deviation of point velocity from the mean, and turbulence intensity are considerably smaller than those recommended by HI for a satisfactory performance of the pump station.