Effect of Cross-Flow Velocity at Forebay on Swirl in Pump Suction Pipe: Hydraulic Model of Seawater Intake at Aliveri Power Plant in Greece

Abstract

The hydraulic performance of pumps in a cooling water intake is directly affected by the nonuniformity of the approach flow at each pump bay, which in turn is influenced by the strength of the cross-flow at the pumps’ common forebay. The effect of the cross-flow velocity at the forebay on the swirl angle in the pump suction pipes is investigated in a hydraulic model of the seawater intake at the Aliveri Power Plant in Greece. The particular intake features two pumps, and a total of 10 cases were examined based on differing values of water depth, number of pumps in operation, and pump flow rate. Velocity measurements at the forebay-dividing cross section were obtained by an acoustic Doppler velocimeter (ADV), while swirl angle in the suction pipe was measured by a vortimeter. A highly nonuniform velocity profile develops at the forebay, when one of the two cleaning channels is closed, and the swirl angle depends solely on the intake forebay geometry when the mean cross-flow velocity drops below a critical value.