Dynamic Surge Behavior of a Centrifugal Pumping System

Abstract

A facility has been constructed to investigate the dynamic surge behavior of centrifugal pumping systems. The facility includes discrete air volumes which can be varied to alter the pumping system’s compliance, and hence susceptibility, to surge. With this facility, the first detailed measurements of surge behavior for a low specific speed, shrouded, centrifugal pump have been obtained and compared with theoretical predictions. The pump tested is a geometrically and dynamically scaled model of a small industrial pump with known surge tendencies. A thorough characterization of the surge phenomenon has been performed, including surge cycle frequency, amplitude, point(s) of inception, and variations with operating point. The results underline the dominant role of: (1) the shape of the pump performance characteristic and (2) the system stability (B) parameter in determining the pump behavior. A simple 1-D model of the pumping system is shown to capture all observed trends in the experimental data. The model accounts for variations in pump wheel speed with mass flow, and employs a first order time lag in pressure rise to model the pump response.