Air entrainment effects on the pressure transients of pumping systems with weir discharge chamber

Abstract

This paper presents a new model for the study of air entrainment on the extreme pressure surges in pumping systems. For the present fluid system considered with a weir discharge chamber, numerical investigations showed that, with the proposed model of the air entrainment, reasonable predictions of transient pressures with proper phasing and attenuation of pressure peaks can be obtained. The results obtained are consistent with observations from field measurements made when the pumps were operating at low pump cutout levels where air entrainment due to attached surface vortex and falling jets from the inflow near the pump intake were present. Further studies were also made on the design characteristics of the weir discharge chamber on the extreme pressure transients for the unsteady flow in the pipeline system with various degrees of air entrainment.