Experimental and Numerical Investigation on a Centrifugal Pump under Air-Water Two-Phase Flow Condition

Abstract

Experimental and numerical investigations have been performed on a single stage, single-suction, horizontal-orientated centrifugal pump under air-water two-phase non condensable flow conditions. Experimental test loop allows performing controlled values of air void fraction for different water flow rates and several rotational speeds. Global pump heads and efficiencies have been measured for several inlet air void fraction values at different rotating speeds up to pump performance breakdown. Similar laws under two-phase flow condition have been investigated at three selected rotating speeds. Numerical calculations have been also performed using URANS approach including k-e turbulence and inhomogeneous two-phase models for nominal rotational speed, the results of which are used to understand some specific experimental results that have been obtained. The results show that the pump performance degradation is more pronounced for low flow rates compared to high flow rates and the similarity laws can also be applied for air-water two phase flow conditions corresponding to the bubbly flow regime, when IVAF is small. Particle fluid model with interface transfer terms looks quite suitable to evaluate pump performance degradation up to IAVF values of 7%. Air bubbles distribute on suction side of the blade and are detained more and more inside the impeller channel near “wake” area when IAVF increase. Bubbles take over 60% part of the channel when IAVF increase to 7% in all three flow rates, which is the reason of the pump performance deterioration.